NDW PART OF
ANALOG
DEVICES LTM 8020
LIL TIEIDHNOLOGY
«H I—
LTM8020
1
8020fe
For more information www.linear.com/LTM8020
TYPICAL APPLICATION
FEATURES
APPLICATIONS
DESCRIPTION
200mA, 36V DC/DC
µModule Regulator
The LT M
®
8020 is a complete 200mA, DC/DC step-down
power supply. Included in the package are the switch-
ing controller, power switches, inductor, and all support
components. Operating over an input voltage range of 4V
to 36V, the LTM8020 supports an output voltage range of
1.25V to 5V, set by a single resistor. Only bulk capacitors
are needed to finish the design. The LTM8020 meets the
radiated emissions requirements of EN55022. Conducted
emission requirements can be met by adding standard
filter components.
The low profile (2.32mm) tiny package enables utilization
of unused space on the bottom of PC boards for high
density point of load regulation.
The LTM8020 is packaged in a thermally enhanced,
compact (6.25mm × 6.25mm) and low profile (2.32mm)
over-molded land grid array (LGA) package suitable for
automated assembly by standard surface mount equip-
ment. The LTM8020 is Pb-free and RoHS compliant.
L, LT, LTC, LTM, µModule, Linear Technology, the Linear logo and Burst Mode are registered
trademarks of Analog Devices, Inc. All other trademarks are the property of their respective
owners.
Efficiency and Power Loss vs Load Current
n Complete Step-Down Switch Mode Power Supply
n Wide Input Voltage Range: 4V to 36V
n 1.25V to 5V Output Voltage
n EN55022 Class B Compliant
n 200mA Output Current
n Current Mode Control
n –55°C to 125°C Operating Temperature
(LTM8020MPV)
n Pb-Free (e4) RoHS Compliant Package with Gold Pad
Finish
n Tiny, Low Profile (6.25mm × 6.25mm × 2.32mm)
Surface Mount LGA Package
n Automotive Battery Regulation
n Power for Portable Products
n Distributed Supply Regulation
n Industrial Supplies
n Wall Transformer Regulation
6.5VIN to 36VIN, 5V at 200mA DC/DC µModule
®
Regulator
VIN VOUT
LTM8020
BIASSHDN
10µF
165k
1%
2.2µF
VIN
*6.5V TO 36V
8020 TA01
GND ADJ
VOUT
5V
200mA
LOAD CURRENT (mA)
30
EFFICIENCY (%)
POWER LOSS (mW)
40
60
80
90
0.1 10 100
3470 TA01b
20
1
70
50
10
1
1000
100
10
0.1
*RUNNING VOLTAGE RANGE. PLEASE REFER TO APPLICATIONS INFORMATION
FOR START-UP DETAILS
LTM8020
TOP \AEW
I
l i
III--
E...-
LTM8020
2
8020fe
For more information www.linear.com/LTM8020
PIN CONFIGURATIONABSOLUTE MAXIMUM RATINGS
VIN, SHDN Voltage ....................................................40V
ADJ Voltage ................................................................5V
BIAS Voltage .............................................................25V
VIN + BIAS Voltage ....................................................47V
VOUT Voltage ............................................................. 10V
Internal Operating Temperature Range ... –40°C to 125°C
Storage Temperature Range .................. –55°C to 125°C
Maximum Solder Temperature ..............................260°C
(Note 1)
TOP VIEW
5
1
2
3
4
EA B C D
SHDN
GND
ADJ
V
OUT
BIAS
VIN
LGA PACKAGE
21-LEAD (6.25mm × 6.25mm × 2.32mm)
TJMAX = 125°C, θJA = 23.1°C/W
θJA DERIVED FROM 5cm × 5cm PCB WITH 4 LAYERS
WEIGHT = 0.25g
LEAD FREE FINISH PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE (Note 2)
LTM8020EV#PBF LTM8020V 21-Lead (6.25mm × 6.25mm) –40°C to 85°C
LTM8020IV#PBF LTM8020V 21-Lead (6.25mm × 6.25mm) –40°C to 85°C
LTM8020MPV#PBF LTM8020MPV 21-Lead (6.25mm × 6.25mm) –55°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
This product is only offered in trays. For more information go to: http://www.linear.com/packaging/. Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
ORDER INFORMATION
http://www.linear.com/product/LTM8020#orderinfo
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Input DC Voltage l4 36 V
VOUT Output DC Voltage 0 < IOUT ≤ 200mA; 167kW < RADJ < ∞ 1.2 5 V
RADJ(MIN) Minimum Allowable RADJ (Note 3) 163 kW
ILK Leakage from IN to OUT VSHDN = 0V, BIAS = 0V 1.2 6 µA
IOUT Continuous Output DC Current 5.5V ≤ VIN ≤ 36V, RADJ = 301k, VO = 3.3V 0 200 mA
IQ(VIN) Quiescent Current into IN SHDN = 0.2V, BIAS Open
BIAS = 3V, Not Switching
BIAS = 0V, Not Switching
l
10
35
1
18
50
µA
µA
µA
IQ(BIAS) Quiescent Current into BIAS SHDN = 0.2V, BIAS = 0V
BIAS = 3V, Not Switching
BIAS = 0V, Not Switching
l
25
0.5
60
1.5
µA
µA
µA
DVOUT/VOUT Line Regulation 5V ≤ VIN ≤ 36V, IOUT = 200mA, RADJ Open 1 %
DVOUT/VOUT Load Regulation VIN = 24V, 0 ≤ IOUT ≤ 200mA, VOUT = 3.3V 2 %
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 10V, VSHDN = 10V, VBIAS = 3V, External CIN = 2.2µF, COUT = 4.7µF.
(Note 2)
LTM8020
LTM8020
3
8020fe
For more information www.linear.com/LTM8020
ILOAD (mA)
EFFICIENCY (%)
90
80
70
60
50
40
30
20
10
0
0.1 10 100 1000
8020 G03
1
12VIN
24VIN
36VIN
ILOAD (mA)
EFFICIENCY (%)
90
80
70
60
50
40
30
20
10
0
0.1 10 100 1000
8020 G01
1
5VIN
12VIN
24VIN
36VIN
ELECTRICAL CHARACTERISTICS
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTM8020E is guaranteed to meet performance specifications
from 0°C to 85°C ambient. Specifications over the full –40°C to
85°C ambient operating temperature range are assured by design,
characterization and correlation with statistical process controls. The
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 10V, VSHDN = 10V, VBIAS = 3V, External CIN = 2.2µF, COUT = 4.7µF.
(Note 2)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VOUT(AC_RMS) Output Ripple (RMS) IOUT = 100mA, VOUT = 3.3V, VIN = 24V 7.5 mV
fSW Switching Frequency IOUT = 200mA 450 kHz
ISC Output Short-Circuit Current VIN = 36V, VOUT = 0V 350 mA
VADJ Voltage at ADJ Pin l1.228 1.265 V
VBIAS(MIN) Minimum BIAS Voltage for Proper
Operation
l3 V
IADJ Current Out of ADJ Pin ADJ = 0V, VOUT = 5V, VSHDN = 0V l9.65 10.35 µA
ISHDN SHDN Pin Current VSHDN = 2.5V 1 5 µA
VIH(SHDN) SHDN Input High Voltage 2.5 V
VIL(SHDN)SHDN Input Low Voltage 0.2 V
LTM8020I is guaranteed to meet specifications over the full –40°C to 85°C
ambient operating temperature range. The LTM8020MP is guaranteed
to meet specifications over the full –55°C to 125°C internal operating
temperature range. Note that the maximum internal temperature is
determined by specific operating conditions in conjunction with board
layout, the rated package thermal resistance and other environmental
factors.
Note 3: Guaranteed by design.
TYPICAL PERFORMANCE CHARACTERISTICS
3.3VOUT Efficiency
3.3VOUT Power Loss
5VOUT Efficiency
IOUT (mA)
POWER LOSS (mW)
1000
100
10
1
0.1
0.1 10 100 1000
8020 G02
1
5VIN
12VIN
24VIN
36VIN
TA = 25°C unless otherwise noted.
LTM8020
1 avg
2 5Vuur
. . . savw
_ SVOUT
— 5Vnur
\
TO START
TO RUN
LTM8020
4
8020fe
For more information www.linear.com/LTM8020
OUTPUT VOLTAGE (V)
1
2
INPUT VOLTAGE (V)
3
4
5
6
2345
4356 G12
7
8
TO START
IOUT = 200mA
TO RUN
INPUT VOLTAGE (V)
0
0
INPUT CURRENT (mA)
20
40
60
80
10 20 30 40
4356 G10
100
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0
OUTPUT CURRENT (A)
0
INPUT CURRENT (A)
0.05 0.10 0.15 0.20
4356 G05
1.8VOUT
2.5VOUT
3.3VOUT
OUTPUT CURRENT (A)
0
0
INPUT CURRENT (A)
0.010
0.020
0.030
0.040
0.05 0.10 0.15 0.20
4356 G07
0.050
0.060 1.8VOUT
2.5VOUT
3.3VOUT
5VOUT
IOUT (mA)
POWER LOSS (mW)
1000
100
10
1
0.1
0.1 10 100 1000
8020 G04
1
12VIN
24VIN
36VIN
TYPICAL PERFORMANCE CHARACTERISTICS
Input Current vs Output Current
(24VIN)
Input Quiescent Current vs Input
Voltage
Input Current vs Input Voltage
(Output Short)
Minimum Required Input Voltage
vs Load (VOUT = 3.3V)
5VOUT Power Loss
Input Current vs Output Current
(5VIN)
Input Current vs Output Current
(12VIN)
OUTPUT CURRENT (A)
0
0
INPUT CURRENT (A)
0.020
0.040
0.060
0.080
0.05 0.10 0.15 0.20
4356 G06
0.100
0.120
1.8VOUT
2.5VOUT
3.3VOUT
5VOUT
OUTPUT CURRENT (A)
0
0
INPUT CURRENT (A)
0.010
0.020
0.005
0.015
0.025
0.030
0.040
0.05 0.10 0.15 0.20
4356 G08
0.035
0.045
1.8VOUT
2.5VOUT
3.3VOUT
5VOUT
Input Current vs Output Current
(36VIN)
INPUT VOLTAGE (V)
0
0
QUIESCENT CURRENT (µA)
1
2
3
4
10 20 30 40
4356 G09
5
Minimum Required Input Voltage
vs Output Voltage
LOAD CURRENT (mA)
0
3.0
INPUT VOLTAGE (V)
3.5
4.0
4.5
5.0
50 100 150 200
4356 G11
5.5
6.0
SHDN CONTROL
TO START
TO RUN
TA = 25°C unless otherwise noted.
LTM8020
LTM8020
5
8020fe
For more information www.linear.com/LTM8020
PIN FUNCTIONS
VIN (Pins A1, A2): The VIN pins supply current to the
LTM8020’s internal regulator and to the internal power
switch. These pins must be locally bypassed with an
external, low ESR capacitor of at least 1µF.
VOUT (Pins A4, A5, B4, B5, C4, C5): Power Output Pins.
An external capacitor is connected from VOUT to GND in
most applications. Apply output load between these pins
and GND.
BIAS (Pin C3): The BIAS pin connects to the internal
boost Schottky diode and to the internal regulator. Tie to
VOUT when VOUT > 3V or to another DC voltage greater
than 3V otherwise. When BIAS > 3V the internal circuitry
will be powered from this pin to improve efficiency. Main
regulator power will still come from VIN.
SHDN (Pin C1): The SHDN pin is used to put the LTM8020 in
shutdown mode. Tie to ground to shut down the LTM8020.
Apply 2V or more for normal operation. If the shutdown
feature is not used, tie this pin to VIN.
GND (Pins C2, D1, D2, D3, D4, D5, E2, E3, E4, E5): The
GND connections serve as the main signal return and the
primary heat sink for the LTM8020. Tie the GND pins to
a local ground plane below the LTM8020 and the circuit
components. Return the feedback divider to this signal.
ADJ (Pin E1): The LTM8020 regulates its ADJ pin to 1.25V.
Connect the adjust resistor from this pin to GND. The
value of this adjust resistor is determined by the equation
RADJ = 623.75/(VOUT – 1.25), where RADJ is in kW. Note
that the ADJ pin is open circuit if VOUT = 1.25V.
TYPICAL PERFORMANCE CHARACTERISTICS
TA = 25°C unless otherwise noted.
INPUT VOLTAGE (V)
0
0
TEMPERATURE RISE (°C)
5
10
15
20
10 20 30 5040
8020 G13
25
3.3VOUT
5VOUT
Temperature Rise vs Input
Voltage (Full Load, TA = 25°C)
Turn-On Behavior
(6VIN, 3.3VOUT, No Load)
VOUT
2V/DIV
SHDN
5V/DIV
INPUT CURRENT
100mA/DIV
50µs/DIV 8020 G14
FREQUENCY (MHz)
0
EMISSIONS LEVEL (dBµV/m)
50
70
90
800
8020 G15
30
10
40
60
80
20
0
–10 200 400 600 1000
36VIN
5VOUT
FULL LOAD
EN55022
CLASS B LIMIT
Radiated Emissions
LTM802O
W\
\
~ ~ ~ W
AAA/VA: 4 A
LTM8020
7
8020fe
For more information www.linear.com/LTM8020
OPERATION
The LTM8020 is a standalone nonisolated step-down
switching DC/DC power supply. It can deliver up to
200mA of DC output current with only bulk external input
and output capacitors. This module provides a precisely
regulated output voltage programmable via one external
resistor from 1.25VDC to 5VDC. The input voltage range
is 4V to 36V. Given that the LTM8020 is a step-down con-
verter, make sure that the input voltage is high enough to
support the desired output voltage and load current. See
Block Diagram.
The LTM8020 contains a current mode controller, power
switching element, power inductor, power Schottky diode
and a modest amount of input and output capacitance.
For some applications, as shown in Table 1, no output
capacitor is necessary.
With its high performance current mode controller and
internal feedback loop compensation, the LTM8020 module
has sufficient stability margin and good transient perfor-
mance under a wide range of operating conditions with a
wide range of output capacitors, even all ceramic ones (X5R
or X7R). Current mode control provides cycle-by-cycle fast
current limit, and automatic current limiting protects the
module in the event of a short circuit or overload fault.
The LTM8020 is built upon a variable frequency control-
ler. The on time, off time and switching frequency are
dependent upon the input voltage, output voltage and
load current.
The drive circuit for the internal power switching element
is powered through the BIAS pin. Power this pin with at
least 3V.
The LTM8020 is equipped with two operating modes,
dependant upon the load current. When the load current
is sufficiently high, the LTM8020 will switch continuously
(see Figure 1a). If the load is very light, or if the input
voltage is high relative to the output voltage, the part will
operate in Burst Mode
®
operation, alternating between its
micropower and switching states to keep the output in
regulation and hold the power dissipation to a minimum
(See Figure 1b).
If the SHDN pin is grounded, all internal circuits are turned
off and VIN current reduces to the device leakage current,
typically a few nanoamps.
Figure 1. Output Voltage and Internal Inductor Current
VOUT
20mV/DIV
IL
100mA/DIV
1ms/DIV
VOUT
20mV/DIV
IL
100mA/DIV
5µs/DIV 8020 F01b
NO LOAD
10mA LOAD
(1b) Burst Mode Operation
VOUT
20mV/DIV
IL
100mA/DIV
1µs/DIV
VOUT
20mV/DIV
IL
100mA/DIV
1µs/DIV
(1a) Continuous Operation
8020 F1a
200mA LOAD
150mA LOAD
LTM8020
. hf
wuk
LTM8020
8
8020fe
For more information www.linear.com/LTM8020
For most applications, the design process is straight
forward, summarized as follows:
1. Look at Table 1 and find the row that has the desired
input range and output voltage.
2. Apply the CIN, COUT, RADJ and BIAS connection indicated
on that row.
While these component combinations have been tested for
proper operation, it is incumbent upon the user to verify
proper operation over the intended system’s line, load and
environmental conditions.
If an output voltage other than those listed in Table 1 is
desired, use the equation RADJ = 623.75/(VOUT – 1.25),
where RADJ is in kW. As a starting point, use values for
CIN and COUT that correspond to the input voltage and
output voltage that most closely matches the intended
application, and verify proper operation over the system’s
line, load and environmental conditions.
Capacitor Selection Considerations
The CIN and COUT capacitor values in Table 1 are the
minimum recommended values for the associated oper-
ating conditions. Applying capacitor values below those
indicated in Table 1 is not recommended, and may result
in undesirable operation. An input system bulk capacitor
is assumed. Using larger values is generally acceptable,
and can yield improved dynamic response, if it is neces-
sary. Again, it is incumbent upon the user to verify proper
operation over the intended system’s line, load and envi-
ronmental conditions.
Ceramic capacitors are small, robust and have very low
ESR. However, not all ceramic capacitors are suitable.
X5R and X7R types are stable over temperature and ap-
plied voltage and give dependable service. Other types,
including Y5V and Z5U have very large temperature and
voltage coefficients of capacitance. In an application cir-
cuit they may have only a small fraction of their nominal
capacitance resulting in much higher output voltage ripple
than expected.
Ceramic capacitors are also piezoelectric. The LTM8020’s
switching frequency depends on the load current, and
at light loads it can excite a ceramic capacitor at audio
APPLICATIONS INFORMATION
frequencies, generating audible noise. Since the LTM8020
operates at a lower current limit during Burst Mode opera-
tion, the noise is typically very quiet to a casual ear.
If this audible noise is unacceptable, use a high performance
electrolytic capacitor at the output. The input capacitor can
be a parallel combination of a 2.2µF ceramic capacitor and
a low cost electrolytic capacitor.
A final precaution regarding ceramic capacitors concerns
the maximum input voltage rating of the LTM8020. A
ceramic input capacitor combined with trace or cable
inductance forms a high Q (under damped) tank circuit.
If the LTM8020 circuit is plugged into a live supply, the
input voltage can ring to twice its nominal value, possi-
bly exceeding the device’s rating. This situation is easily
avoided; see the Hot-Plugging Safely section.
Shorted Input Protection
Care needs to be taken in systems where the output will be
held high when the input to the LTM8020 is absent. This
may occur in battery charging applications or in battery
backup systems where a battery or some other supply
is diode ORed with the LTM8020’s output. If the VIN pin
is allowed to float and the SHDN pin is held high (either
by a logic signal or because it is tied to VIN), then the
LTM8020’s internal circuitry will pull its quiescent current
from its output. This is fine if your system can tolerate a
few milliamps in this state. If you ground the SHDN pin,
this quiescent current will drop to essentially zero. How-
ever, if the VIN pin is grounded while the output is held
high, then parasitic diodes inside the LTM8020 can pull
large currents from the output through the internal power
switch, possibly damaging the device. Figure 2 shows a
circuit that will run only when the input voltage is present
and that protects against a shorted or reversed input.
Figure 2. Diode D1 Prevents a Shorted Input from Discharging
a Backup Battery Tied to the Output, as Well as Protecting the
LTM8020 from a Reversed Input
VIN
LTM8020
SHDN
VIN
8020 F02
GND
D1
100k
1M
LTM8020
LTM8020
9
8020fe
For more information www.linear.com/LTM8020
APPLICATIONS INFORMATION
PCB Layout
Most of the headaches associated with PCB layout have
been alleviated or even eliminated by the high level of
integration of the LTM8020. The LTM8020 is never-the-
less a switching power supply, and care must be taken to
minimize EMI and ensure proper operation. Even with the
high level of integration, you may fail to achieve specified
operation with a haphazard or poor layout. See Figure 3
for a suggested layout.
Ensure that the grounding and heat sinking are acceptable.
A few rules to keep in mind are:
1. Place the CIN capacitor as close as possible to the VIN
and GND connection of the LTM8020.
2. Place the COUT capacitor as close as possible to the
VOUT and GND connection of the LTM8020.
3. Place the CIN and COUT capacitors such that their
ground current flows directly adjacent or underneath
the LTM8020.
4. Connect all of the GND connections to as large a copper
pour or plane area as possible on the top layer. Avoid
breaking the ground connection between the external
components and the LTM8020.
5. The copper pours also serve as the heat sink for the
LTM8020. Place several vias in the GND plane to act as
heat pipes to other layers of the printed circuit board.
Positive-to-Negative Voltage Regulation
The LTM8020 can generate a negative output by tying the
VOUT pads to system ground and connecting GND as shown
in the Typical Applications section. In this configuration,
SHDN must be level shifted or referenced to GND, and the
available output current may be reduced.
Hot-Plugging Safely
The small size, robustness and low impedance of ceramic
capacitors make them an attractive option for the input
bypass capacitor of LTM8020. However, these capacitors
can cause problems if the LTM8020 is plugged into a live
supply (see Linear Technology Application Note 88 for
a complete discussion). The low loss ceramic capacitor
combined with stray inductance in series with the power
source forms an under damped tank circuit, and the volt-
age at the VIN pin of the LTM8020 can ring to twice the
nominal input voltage, possibly exceeding the LTM8020’s
rating and damaging the part. If the input supply is poorly
controlled or the user will be plugging the LTM8020 into
an energized supply, the input network should be designed
to prevent this overshoot. Figure 4 shows the waveforms
that result when an LTM8020 circuit is connected to a 24V
supply through six feet of 24-gauge twisted pair. The first
plot is the response with a 2.2µF ceramic capacitor at the
input. The input voltage rings as high as 35V and the input
current peaks at 20A. One method of damping the tank
circuit is to add another capacitor with a series resistor to
the circuit. In Figure 4b an aluminum electrolytic capacitor
has been added. This capacitor’s high equivalent series
resistance damps the circuit and eliminates the voltage
overshoot. The extra capacitor improves low frequency
ripple filtering and can slightly improve the efficiency of the
circuit, though it is likely to be the largest component in the
circuit. An alternative solution is shown in Figure 4c. A 1W
resistor is added in series with the input to eliminate the
voltage overshoot (it also reduces the peak input current).
A 0.1µF capacitor improves high frequency filtering. This
solution is smaller and less expensive than the electrolytic
capacitor. For high input voltages its impact on efficiency
is minor, reducing efficiency less than one-half percent for
a 5V output at full load operating from 24V.
Figure 3. Layout Showing Suggested External
Components, GND Plane and Thermal Vias
GND
VIAs TO GND PLANE
VOUT
ADJ
COPPER
BIAS
SHDN
VIN
COUT
RADJ
CIN
8020 F03
LTM8020
‘IO
LTM8020
10
8020fe
For more information www.linear.com/LTM8020
High Temperature Considerations
The die temperature of the LTM8020 must be lower than
the maximum rating of 125°C, so care should be taken
in the layout of the circuit to ensure good heat sinking of
the LTM8020. To estimate the junction temperature, ap-
proximate the power dissipation within the LTM8020 by
applying the typical efficiency stated in this data sheet to
the desired output power, or, if you have an actual module,
by taking a power measurement. Then calculate the inter-
nal temperature rise of the LTM8020 above the surface
of the printed circuit board by multiplying the module’s
power dissipation by the thermal resistance. The actual
thermal resistance of the LTM8020 to the printed circuit
board depends upon the layout of the circuit board, but the
thermal resistance given in the Pin Configuration, which is
based upon a 25cm2 4-layer FR4 PC board, and the Typical
Performance Characteristics can be used a guide.
Finally, be aware that at high ambient temperatures the
internal Schottky diode will have significant leakage current
increasing the quiescent current of the LTM8020.
BIAS Pin Considerations
The BIAS pin is used to provide drive power for the internal
power switching stage and operate internal circuitry. For
proper operation, it must be powered by at least 3V. If the
output voltage is programmed to be 3V or higher, simply
tie BIAS to VOUT. If VOUT is less than 3V, BIAS can be tied
to VIN or some other voltage source. In all cases, ensure
that the maximum voltage at the BIAS pin is both less than
25V and the sum of VIN and BIAS is less than 47V. If BIAS
power is applied from a remote or noisy voltage source, it
may be necessary to apply a decoupling capacitor locally
to the LTM8020.
APPLICATIONS INFORMATION
Figure 4. A Well Chosen Input Network Prevents Input Voltage Overshoot and Ensures
Reliable Operation When the LTM8020 is Connected to a Live Supply
+
LTM8020
2.2µF
VIN
10V/DIV
IIN
10A/DIV
VIN
10V/DIV
IIN
10A/DIV
VIN
10V/DIV
IIN
10A/DIV
10µs/DIV
10µs/DIV
10µs/DIV
VIN
CLOSING SWITCH
SIMULATES HOT PLUG
IIN
(4a)
(4b)
(4c)
LOW
IMPEDANCE
ENERGIZED
24V SUPPLY
STRAY
INDUCTANCE
DUE TO 6 FEET
(2 METERS) OF
TWISTED PAIR
+
LTM8020
2.2µF
10µF
35V
AI.EI.
LTM8020
2.2µF0.1µF
1Ω
8020 F04
LTM8020
‘I‘I
LTM8020
11
8020fe
For more information www.linear.com/LTM8020
APPLICATIONS INFORMATION
Table 1. Recommended External Component Values and Configuration
VIN RANGE VOUT CIN COUT RADJ BIAS CONNECTION
4.5V - 36V 1.25V 2.2µF 50V 1206 X7R 47µF 6.3V 1206 X5R Open >2V, < 25V
4.5V - 36V 1.5V 2.2µF 50V 1206 X7R 47µF 6.3V 1206 X5R 2.43M >2V, < 25V
4.5V - 36V 1.8V 2.2µF 50V 1206 X7R 47µF 6.3V 1206 X5R 1.1M >2V, < 25V
4.5V - 36V 2.5V 2.2µF 50V 1206 X7R 22µF 6.3V 1206 X7R 499k VOUT
4.5V - 36V 3.3V 2.2µF 50V 1206 X7R 10µF 6.3V 1206 X7R 301k VOUT
6.5V - 36V 5V 2.2µF 50V 1206 X7R 10µF 6.3V 1206 X7R 165k VOUT
4.5V - 15V 1.25V 2.2µF 16V 0805 X7R 22µF 6.3V 1206 X7R Open VIN
4.5V - 15V 1.5V 2.2µF 16V 0805 X7R 10µF 6.3V 0805 X7R 2.43M VIN
4.5V - 15V 1.8V 2.2µF 16V 0805 X7R 10µF 6.3V 0805 X7R 1.1M VIN
4.5V - 15V 2.5V 2.2µF 16V 0805 X7R 10µF 6.3V 0805 X7R 499k VIN
4.5V - 15V 3.3V 2.2µF 16V 0805 X7R 10µF 6.3V 0805 X7R 301k VOUT
6.5V - 15V 5V 2.2µF 16V 0805 X7R None 165k VOUT
9V - 24V 1.25V 1µF 25V 0805 X7R 47µF 6.3V 0805 X5R Open VIN
9V - 24V 1.5V 1µF 25V 0805 X7R 47µF 6.3V 0805 X7R 2.43M VIN
9V - 24V 1.8V 1µF 25V 0805 X7R 10µF 6.3V 0805 X7R 1.1M VIN
9V - 24V 2.5V 1µF 25V 0805 X7R 10µF 6.3V 0805 X7R 499k VIN
9V - 24V 3.3V 1µF 25V 0805 X7R 10µF 6.3V 0805 X7R 301k VOUT
9V - 24V 5V 4.7µF 25V 0805 X7R 10µF 6.3V 0805 X5R 165k VOUT
18V - 36V 1.25V 2.2µF 50V 1206 X7R 47µF 6.3V 1206 X5R Open >2V, <25V
18V - 36V 1.5V 2.2µF 50V 1206 X7R 47µF 6.3V 1206 X5R 2.43M >2V, <25V
18V - 36V 1.8V 2.2µF 50V 1206 X7R 22µF 6.3V 1206 X7R 1.1M >2V, <25V
18V - 36V 2.5V 2.2µF 50V 1206 X7R 10µF 6.3V 0805 X7R 499k VOUT
18V - 36V 3.3V 2.2µF 50V 1206 X7R 10µF 6.3V 0805 X7R 301k VOUT
18V - 36V 5V 2.2µF 50V 1206 X7R 10µF 6.3V 0805 X7R 165k VOUT
3.3V - 30V –3.3V 2.2µF 50V 1206 X7R 22µF 6.3V 0805 X7R 301k VOUT
5V - 30V –5V 2.2µF 50V 1206 X7R 10µF 6.3V 0805 X7R 165k VOUT
Minimum Input Voltage
The LTM8020 is a step-down converter, so a minimum
amount of headroom is required to keep the output in
regulation. For most applications at full load, the input
needs to be at least 1.5V above the desired output. In
addition, the input voltage required to turn on depends
upon how the SHDN pin is tied. It takes more input voltage
to turn on if SHDN is tied to VIN than if the turn-on is
controlled by raising SHDN when VIN is in the required
operating range. A graph of the input voltage required to
turn the LTM8020 on when SHDN is tied to VIN or when
SHDN is switched is given in the Typical Performance
Characteristics section.
Electromagnetic Compliance
The LTM8020 was evaluated by an independent nationally
recognized test lab and found to be compliant with EN55022
class B: 2006 by a wide margin. A sample graph of the
LTM8020’s radiated EMC performance is given in the
Typical Performance Characteristics section, while further
data, operating conditions and test setup are detailed in
the electromagnetic compatibility test report, available
on the Linear Technology website. Conducted emissions
requirements may be met by adding an appropriate input
power line filter. The proper implementation of this filter
depends upon the system operating and performance
conditions as a whole, of which the LTM8020 is typically
only a component, so conducted emissions are not
addressed at this level.
LTM8020
«H I—
-IH |~
12
LTM8020
12
8020fe
For more information www.linear.com/LTM8020
VIN (V)
0
0
I
LOAD
(mA)
50
100
150
200
10 155 20 3025
8020 TA08
250
VIN VOUT
LTM8020
BIAS
SHDN
10µF
X5R
165k
1%
2.2µF
–5V
VIN*
5V TO 30V
8020 TA06
ADJ GND –5V
85mA
OPTIONAL
SCHOTTKY
CLAMP
–5V Positive-to-Negative Converter
VIN VOUT
LTM8020
BIASSHDN
165k
1%
2.2µF
VIN*
6.5V TO 15V
8020 TA05
GND ADJ
VOUT
5V
200mA
5V Step-Down Converter (No Output Capacitor Required)
TYPICAL APPLICATIONS
VIN VOUT
LTM8020
SHDN
47µF
X5R
1µF
VIN*
4.5V TO 24V
8020 TA02
GND ADJ
VOUT
1.25V
200mA
BIAS
VIN VOUT
LTM8020
BIASSHDN
10µF
X5R
301k
1%
1µF
VIN*
4.5V TO 36V
8020 TA04
GND ADJ
VOUT
3.3V
200mA
1.25V Step-Down Converter 3.3V Step-Down Converter
VIN VOUT
LTM8020
SHDN
BIAS 22µF
X7R
1.1M
1%
2.2µF
VIN*
4.5V TO 15V
8020 TA03
GND ADJ
VOUT
1.8V
200mA
1.8V Step-Down Converter
–5V Positive-to-Negative Converter
Output vs Input Voltage
*
* RUNNING VOLTAGE RANGE. PLEASE REFER TO APPLICATIONS INFORMATION FOR START-UP DETAILS
LTM8020
13
LTM8020
13
8020fe
For more information www.linear.com/LTM8020
PACKAGE DESCRIPTION
NOTES:
1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994
2. ALL DIMENSIONS ARE IN MILLIMETERS
LAND DESIGNATION PER JESD MO-222, SPP-010 AND SPP-020
5. PRIMARY DATUM -Z- IS SEATING PLANE
6. THE TOTAL NUMBER OF PADS: 21
4
3
DETAILS OF PAD #1 IDENTIFIER ARE OPTIONAL,
BUT MUST BE LOCATED WITHIN THE ZONE INDICATED.
THE PAD #1 IDENTIFIER MAY BE EITHER A MOLD OR A
MARKED FEATURE
SYMBOL
aaa
bbb
TOLERANCE
0.15
0.10
2.22 – 2.42
DETAIL A
PACKAGE SIDE VIEW
DETAIL A
SUBSTRATE
MOLD
CAP
0.27 – 0.37
2.5400
2.5400
1.2700
1.2700
0.0000
1.95 – 2.05
bbb Z
Z
6.250
BSC
PACKAGE TOP VIEW
LGA 21 0113 REV B
6.250
BSC
4
PAD 1
CORNER
3
PADS
SEE NOTES
XY
aaa Z
aaa Z
2.5400
1.5875
0.9525
1.2700
0.3175
0.3175
0.0000
2.5400
SUGGESTED PCB LAYOUT
TOP VIEW
1.2700
0.0000
1.27O
BSC
0.605 – 0.665
0.605 – 0.665
5.080
5.080
BSC
C(0.30)
PAD 1
E A
5
1
2
3
4
BC
BOTTOM VIEW
D
LTMXXXXXX
µModule
TRAY PIN 1
BEVEL
PACKAGE IN TRAY LOADING ORIENTATION
COMPONENT
PIN “A1”
LGA Package
21-Lead (6.25mm × 6.25mm × 2.32mm)
(Reference LTC DWG # 05-08-1803 Rev B)
7 PACKAGE ROW AND COLUMN LABELING MAY VARY
AMONG µModule PRODUCTS. REVIEW EACH PACKAGE
LAYOUT CAREFULLY
!
7
SEE NOTES
Please refer to http://www.linear.com/product/LTM8020#packaging for the most recent package drawings.
LTM8020
15
LTM8020
15
8020fe
For more information www.linear.com/LTM8020
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
REVISION HISTORY
REV DATE DESCRIPTION PAGE NUMBER
D 3/10 Changes to Description and Features.
Changes to Applications Information.
“Electromagnetic Compliance” Paragraph Added to Applications Information.
Changes to Typical Application.
1
8
11
13
E 8/17 Corrected –5V circuit from IOUT of 85µA to 85mA. 12
(Revision history begins at Rev D)
LTM8020
_L
I __
i I
16 L7LJIJE1‘B \ WW2
LTM8020
16
8020fe
For more information www.linear.com/LTM8020
LINEAR TECHNOLOGY CORPORATION 2007
LT 0817 • PRINTED IN USA
www.linear.com/LTM8020
PART NUMBER DESCRIPTION COMMENTS
LTM4600 10A DC/DC µModule Basic 10A DC/DC µModule, 15mm × 15mm × 2.8mm LGA
LTM4600HVMPV Military Plastic 10A DC/DC µModule –55°C to 125°C Operation, 15mm × 15mm × 2.8mm LGA
LTM4601/
LTM4601A
12A DC/DC µModule with PLL, Output Tracking/Margining
and Remote Sensing
Synchronizable, PolyPhase Operation, LTM4601-1 Version has no
Remote Sensing
LTM4602 6A DC/DC µModule Pin Compatible with the LTM4600
LTM4603 6A DC/DC µModule with PLL and Output Tracking/
Margining and Remote Sensing
Synchronizable, PolyPhase Operation, LTM4603-1 Version has no
Remote Sensing, Pin Compatible with the LTM4601
LTM4604 4A Low VIN DC/DC µModule 2.375V ≤ VIN ≤ 5V, 0.8V ≤ VOUT ≤ 5V, 9mm × 15mm × 2.3mm LGA
LTM4608 8A Low VIN DC/DC µModule 2.375V ≤ VIN ≤ 5V, 0.8V ≤ VOUT ≤ 5V, 9mm × 15mm × 2.8mm LGA
LTM8022 1A, 36V DC/DC µModule Adjustable Frequency, 0.8V ≤ VOUT ≤ 5V, 11.25mm × 9mm × 2.82mm,
Pin Compatible to the LTM8023
LTM8023 2A, 36V DC/DC µModule Adjustable Frequency, 0.8V ≤ VOUT ≤ 5V, 11.25mm × 9mm × 2.82mm,
Pin Compatible to the LTM8022
RELATED PARTS
TYPICAL APPLICATION
VIN VOUT
LTM8020
BIASSHDN
10µF
X5R
301k
1%
1µF
VIN
5V TO 36V
8020 TA07
GND ADJ
VOUT
3.3V
200mA
3.3V Step-Down Converter
*
*RUNNING VOLTAGE RANGE. PLEASE REFER TO APPLICATIONS INFORMATION FOR START-UP DETAILS
Products related to this Datasheet
DC DC CONVERTER 1.25-5V
DC DC CONVERTER 1.25-5V
DC DC CONVERTER 1.25-5V
BOARD EVAL LTM8020