Analog Devices Inc. 的 LT3469 规格书

L7 LI”! / “2 LT3469 TECHNOLOGY L7LJL1%
LT3469
1
3469f
Amplifier
■
Current Limit: ±40mA Typical
■
Input Common Mode Range: 0V to 10V
■
Output Voltage Range: 1V to (V
CC
– 1V)
■
Differential Gain Stage with High Impedance Output
(g
m
Stage)
■
Quiescent Current (from V
CC
): 2mA
■
Unloaded Gain: 30,000 Typical
Switching Regulator
■
Generates V
CC
Up to 35V
■
Wide Operating Supply Range: 2.5V to 16V
■
High Switching Frequency: 1.3MHz
■
Internal Schottky Diode
■
Tiny External Components
■
Current Mode Switcher with Internal Compensation
■
Low Profile (1mm) SOT-23 Package
Piezo Microactuator Driver
with Boost Regulator
■
Piezo Speakers
■
Piezo Microactuators
■
Varactor Bias
, LTC and LT are registered trademarks of Linear Technology Corporation.
+
–
+IN
35
6
2
4
1
8
7
GND
FB
V
CC
SW
LT3469
V
IN
453k
16.5k
0.47µF
50V
V
OUT
1V TO 33V
PIEZO
ACTUATOR
5nF < C
<
300nF
10k
+
–
9.09k
100k
47µH
–IN OUT
3469 TA03
5V OR 12V
INPUT
0V TO 3V
1µF
16V
The LT
®
3469 is a transconductance (g
m
) amplifier that can
drive outputs up to 33V from a 5V or 12V supply. An
internal switching regulator generates a boosted supply
voltage for the g
m
amplifier. The amplifier can drive
capacitive loads in the range of 5nF to 300nF. Slew rate is
limited only by the maximum output current. The 35V
output voltage capability of the switching regulator, along
with the high supply voltage of the amplifier, combine to
allow the wide output voltage range needed to drive a
piezoceramic microactuator.
The LT3469 switching regulator switches at 1.3MHz,
allowing the use of tiny external components. The output
capacitor can be as small as 0.22µF, saving space and cost
versus alternative solutions.
The LT3469 is available in a low profile ThinSOT
TM
package.
ThinSOT is a trademark of Linear Technology Corporation.
Piezo Microactuator Driver
Response Driving a 33nF Load
I
OUT
100mA/DIV
V
OUT
10V/DIV
INPUT
5V/DIV
50µs/DIV 3469 TA04
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
33:: DEC:
LT3469
2
3469f
V
IN
Voltage ............................................................. 16V
SW Voltage ............................................................. 40V
V
CC
Voltage............................................................. 38V
+IN, –IN Voltage ..................................................... 10V
FB Voltage ................................................................ 3V
Current Into SW Pin ................................................. 1A
Operating Temperature Range (Note 2) .. –40°C to 85°C
Storage Temperature Range ................ –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART
NUMBER
(Note 1)
ABSOLUTE AXI U RATI GS
WWWU
Consult LTC Marketing for parts specified with wider operating temperature ranges.
LT3469ETS8
T
JMAX
= 125°C, θ
JA
= 250°C/W
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (Note 2) VIN = 5V, VCC = 35V, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
TS8 PART MARKING
LTACA
OUT 1
FB 2
V
IN
3
GND 4
8 –IN
7 +IN
6 V
CC
5 SW
TOP VIEW
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
PARAMETER CONDITIONS MIN TYP MAX UNITS
g
m
Amplifier
Input Offset Voltage V
OUT
= V
CC
/2 ●310 mV
Input Offset Current ●10 100 nA
Input Bias Current ●150 500 nA
Input Resistance—Differential Mode 1MΩ
Input Resistance—Common Mode 200 MΩ
Common Mode Rejection Ratio V
CM
= 0V to 10V 70 100 dB
Power Supply Rejection Ratio—V
IN
V
IN
= 2.5V to 16V 80 120 dB
Power Supply Rejection Ratio—V
CC
V
CC
= 15V to 35V 65 85 dB
Gain No Load, V
OUT
= 2V to 33V 15 30 V/mV
R
L
= 200k, V
OUT
= 2V to 33V 10 20 V/mV
Transconductance I
OUT
= ±100µA 160 220 260 µA/mV
●140 300 µA/mV
Maximum Output Current V
OUT
= V
CC
/2 ±30 ±40 ±55 mA
●±23 ±58 mA
Maximum Output Voltage, Sourcing V
CC
= 35V, I
OUT
= 10mA 34.0 34.5 V
V
CC
= 35V, I
OUT
= 0mA 34.5 34.9 V
Minimum Output Voltage, Sinking I
OUT
= –10mA 200 1000 mV
I
OUT
= 0mA 10 500 mV
Output Resistance V
CC
= 35V, V
OUT
= 2V to 33V 100 kΩ
Supply Current—V
CC
V
CC
= 35V 1.5 2 2.5 mA
Switching Regulator
Minimum Operating Voltage 2.5 V
Maximum Operating Voltage 16 V
Feedback Voltage ●1.19 1.23 1.265 V
FB Pin Bias Current ●45 200 nA
FB Line Regulation 2.5V < V
IN
< 16V 0.03 %/V
Supply Current—V
IN
1.9 2.6 mA
Switching Frequency ●0.8 1.3 1.7 MHz
Maximum Duty Cycle ●88 91 %
Switch Current Limit (Note 3) ●165 220 mA
Switch V
CESAT
I
SW
= 100mA 350 500 mV
PACKAGE/ORDER I FOR ATIO
UU
W
L7LJL1%
LT3469
3
3469f
PARAMETER CONDITIONS MIN TYP MAX UNITS
Switch Leakage Current V
SW
= 5V 0.01 1 µA
Diode V
F
I
D
= 100mA 740 1100 mV
Diode Reverse Leakage Current V
R
= 5V 0.1 1 µA
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (Note 2) VIN = 5V, VCC = 35V, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LT3469E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3: Current limit is guaranteed by design and/or correlation to static
test. Slope compensation reduces current limit at higher duty cycles.
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Schottky Forward Voltage
Schottky Reverse Leakage
FORWARD VOLTAGE (mV)
200
SCHOTTKY CURRENT (mA)
150
200
250
500 700 1000
3469 G07
100
50
0300 400 600 800 900
100°C
–50°C
25°C
TEMPERATURE (°C)
–50
0
LEAKAGE CURRENT (µA)
5
10
15
20
25
–25 02550
3469 G09
75 100
VR = 5V
Switching Frequency FB Pin Voltage and Bias Current
TEMPERATURE (°C)
–50
1.4
1.2
1.0
0.8
0.6
0.4
0.2
025 75
3469 G10
–25 0 50 100
SWITCHING FREQUENCY (MHz)
TEMPERATURE (°C)
–50
1.175
FB VOLTAGE (V)
FB BIAS CURRENT (nA)
1.195
1.215
1.235
1.255
1.275
0
10
20
30
40
50
–25 02550
3469 G11
75 100
CURRENT
VOLTAGE
(Switching Regulator)
V
IN
(V)
0
I
Q
(mA)
1.2
1.8
2.0
16
3469 G05
1.0
0.8
04812 14
2610
0.4
2.4
2.2
1.6
1.4
0.6
0.2
–50°C
100°C
25°C
DUTY CYCLE (%)
0
CURRENT LIMIT (mA)
150
200
250
80
3469 G06
100
50
020 40 60 100
T
A
= 25°C
VIN Quiescent Current Current Limit vs Duty Cycle
mum H H 750°C 5°C mum
LT3469
4
3469f
TYPICAL PERFOR A CE CHARACTERISTICS
UW
VCC Quiescent Current Output Current
vs Differential Input Voltage
V
CC
(V)
15 18
0
I
Q
(mA)
1.0
2.5
21 27 30
3469 G01
0.5
2.0
100°C
25°C–50°C
1.5
24 33 36
DIFFERENTIAL INPUT VOLTAGE (mV)
–50
OUTPUT CURRENT (mA)
0
10
20
30
30
3469 G02
–10
–20
–5
5
15
25
–15
–25
–30 –30 –10 10
–40 40
–20 020 50
100°C
–50°C
25°C
(g
m
Amplifier)
gm vs VCC
V
CC
(V)
15
g
m
(µA/mV)
100
150
35
3469 G14
50
020 25 30
250
200
–50°C25°C
100°C
UU
U
PI FU CTIO S
OUT (Pin 1): Output of the g
m
Amplifier. There must be at
least 5nF of capacitive load at the output in a gain of 10
configuration. Capacitive loads up to 300nF can be con-
nected to this pin. Piezo actuators below 5nF can be driven
if capacitance is placed in parallel to bring the total
capacitance to 5nF.
FB (Pin 2): Feedback Pin. Reference voltage is 1.23V.
Connect feedback resistor divider here.
V
IN
(Pin 3): Input Supply Pin. Must be locally bypassed.
GND (Pin 4): Ground Pin. Connect directly to local ground
plane.
SW (Pin 5): Switch Pin. Connect inductor here. Minimize
trace area at this pin to reduce EMI.
V
CC
(Pin 6): Output of Switching Regulator and Supply
Rail for g
m
Amp. There must be 0.22µF or more of
capacitance here.
+IN (Pin 7): Noninverting Terminal of the g
m
Amplifier.
–IN (Pin 8): Inverting Terminal of the g
m
Amplifier.
BLOCK DIAGRA
W
–
+
SW
4
5V
CC
2
FB
1.23V
7
1
V
IN
V
CC
+IN
–IN
OUT
GND
3469 F01
Q1
A1 SWITCH
CONTROLLER
6
V
IN
3
–
+
8
g
m
Figure 1. LT3469 Block Diagram
W‘TH PHASE 5003f CAPACHOR THDUT PHASE ST CAPAmToR L7LJL1%
LT3469
5
3469f
OPERATIO
U
g
m
Amplifier
The LT3469 is a wide output voltage range g
m
amplifier
designed to drive capacitive loads. Input common mode
range extends from 10V to ground. The output current is
proportional to the voltage difference across the input
terminals. When the output voltage has settled, the input
terminals will be at the same voltage; supply current of the
amplifier will be low and power dissipation will be low. If
presented with an input differential, however, the output
current can increase significantly, up to the maximum
output current (typically 40mA). The output voltage slew
rate is determined by the maximum output current and the
output capacitance, and can be quite high. With a 10nF
load, the output slew rate will typically be 4V/µs. The
capacitive load compensates the g
m
amplifier and must be
present for stable operation. The gain capacitance product
of the amplifier must be at least 50nF. For example, if the
amplifier is operated in a gain of 10 configuration, a
minimum capacitance of 5nF is necessary. In a gain of 20
configuration, a minimum of 2.5nF is necessary. Closed
loop –3dB bandwidth is set by the output capacitance.
Typical closed loop bandwidth is approximately:
g
AC
m
V OUT
2π••
where g
m
= 200µA/mV
For example, an amplifier in a gain of 10 configuration with
10nF of output capacitance will have a closed loop –3dB
bandwidth of approximately 300kHz. Figure 3 shows typi-
cal bandwidth of a gain of 10 configuration per output
capacitance.
In applications where negative phase contributions below
crossover frequency must be minimized, a phase boost
capacitor can be added, as shown in Figure 4. Larger val-
ues of C
BOOST
will further reduce the closed-loop negative
phase con
tri
bution, however, the amplifier phase margin
will be reduced. For an amplifier phase margin of approxi-
mately 55°, select C
BOOST
as follows:
CCRR
gRR
BOOST OUT
m
=+
()
()
121
12
/
||
where g
m
= 200µA/mV.
In a gain of 10 configuration, choosing C
BOOST
as de-
scribed will lead to nearly zero closed-loop negative phase
contribution at 3kHz for values of C
OUT
from 10nF to
200nF. The phase boost capacitor should not be used if
C
OUT
is less than twice the minimum for stable operation.
The gain capacitance product should therefore be higher
than 100nF if a phase boost capacitor is used.
Switching Regulator
The LT3469 uses a constant frequency, current mode
control scheme to provide excellent line and load regula-
tion. Operation can be best understood by referring to the
Block Diagram in Figure 1. The switch controller sets the
peak current in Q1 proportional to its input. The input to the
switch controller is set by the error amplifier, A1, and is
Figure 2. Slew Rate vs Capacitance Figure 3. Closed Loop –3dB Bandwidth
vs Capacitance in a Gain of 10 Configuration
CAPACITANCE (nF)
2
0.1
SLEW RATE (V/µs)
1
10
100
20 200
3469 F02
CAPACITANCE (nF)
2
BANDWIDTH (kHz)
10
100
1000
20 200
3469 F03
WITH PHASE
BOOST CAPACITOR
WITHOUT PHASE
BOOST CAPACITOR
”HF III-w L7LJEJW
LT3469
6
3469f
OPERATIO
U
transient response, however, more output capacitance can
help limit the voltage droop on V
CC
during transients.
Table 2. Recommended Ceramic Capacitor Manufacturers
MANUFACTURER PHONE URL
Taiyo Yuden 408-573-4150 www.t-yuden.com
AVX 843-448-9411 www.avxcorp.com
Murata 814-237-1431 www.murata.com
Kemet 408-986-0424 www.kemet.com
Inrush Current Considerations When Hot Plugging
When the supply voltage is applied to VIN, the voltage
difference between VIN and VCC generates inrush current
flowing from the input through the inductor, the SW pin,
and the integrated Schottky diode to charge the output
capacitor. Care should be taken not to exceed the LT3469
maximum SW pin current rating of 1A. Worst-case inrush
current occurs when the application circuit is hot plugged
into a live supply with a large output capacitance. The
typical application circuit will maintain a peak SW pin
current below 1A when it is hot plugged into a 5V supply.
To keep SW pin current below 1A during a hot plug into
a 12V supply, 4.7Ω must be added between the supply
and the LT3469 input capacitor. During normal operation,
the SW pin current remains significantly less than 1A.
Layout Hints
As with all switching regulators, careful attention must be
paid to the PCB board layout and component placement.
To maximize efficiency, switch rise and fall times are made
3469 F04
–
+
C
BOOST
R2
R1
V
OUT
g
m
INPUT
Figure 4. Boosting the Bandwidth of the gm Amplifier
with Capacitance On the Inverting Input
simply an amplified version of the difference between the
feedback voltage and the reference voltage of 1.23V. In
this manner, the error amplifier sets the correct peak
current level to keep the output in regulation. If the error
amplifier’s output increases, more current is delivered to
the output; if it decreases, less current is delivered. The
switching regulator provides the boosted supply voltage
for the g
m
amplifier.
Inductor Selection
A 47µH inductor is recommended for most LT3469 appli-
cations. Some suitable inductors with small size are listed
in Table 1. The efficiency comparison of different induc-
tors is shown in Figure 5.
Table 1. Recommended Inductors
CURRENT
DCR RATING
PART NUMBER (Ω) (mA) MANUFACTURER
LQH32CN470 1.3 170 Murata
814-237-1431
www.murata.com
CMD4D11-470 2.8 180 Sumida
847-545-6700
www.Sumida.com
LBC2518T470M 1.9 150 Taiyo Yuden
408-573-4150
www.t-yuden.com
Capacitor Selection
The small size of ceramic capacitors makes them ideal for
LT3469 applications. X5R and X7R types are recommended
because they retain their capacitance over wider voltage and
temperature ranges than other types such as Y5V or Z5U.
A 1µF input capacitor is sufficient for most LT3469 appli-
cations. A 0.22µF output capacitor is sufficient for stable
LOAD CURRENT (mA)
0
40
EFFICIENCY (%)
50
60
70
510 15 20
3469 F05
25
80
90
45
55
65
75
85
30
VIN = 12V
VOUT = 35V
MURATA LQH32CN470
SUMIDA CMD4011-470
TAIYO YUDEN LBC2518T470M
Figure 5. Efficiency Comparison of Different Inductors
L7LJL1%
LT3469
7
3469f
as short as possible. To prevent electromagnetic interfer-
ence (EMI) problems, proper layout of the high frequency
switching path is essential. The voltage signal of the SW
pin has sharp rise and fall edges. The SW pin should be
surrounded on three sides by metal connected to V
CC
to
shield +IN and –IN. Minimize the area of all traces con-
nected to the SW pin and always use a ground plane under
the switching regulator to minimize interplane coupling. In
addition, the ground connection for the feedback resistor
R1 should be tied directly to the GND pin and not shared
with any other component, ensuring a clean, noise-free
connection. The ground return of the piezoceramic
microactuator should also have a direct and unshared
connection to the GND pin. The GND connection to R5
should be tied directly to the ground of the source gener-
ating the INPUT signal to avoid error induced by voltage
drops along the GND line. Recommended component
placement is shown in Figure 6.
Thermal Considerations and Power Dissipation
The LT3469 combines large output drive with a small
package. Because of the high supply voltage capability, it
is possible to operate the part under conditions that
exceed the maximum junction temperature. Maximum
junction temperature (T
J
) is calculated from the ambient
temperature (T
A
) and power dissipation (P
D
) as follows:
T
J
= T
A
+ (P
D
• 250°C/W)
Worst-case power dissipation occurs at maximum output
swing, frequency, capacitance and V
CC
. For a square wave
input, power dissipation is calculated from the amplifier
quiescent current (I
Q
), input frequency (f), output swing
(V
OUT(P-P)
), capacitive load (C
L
), amplifier supply voltage
(V
CC
) and switching regulator efficiency (η) as follows:
PIfV CV
DQLCC
=+
()
()
OUT(P-P)
η
Example: LT3469 at T
A
= 70°C, V
CC
= 35V, C
L
= 200nF,
f = 3kHz, V
OUT(P-P)
= 4V, η = 80%:
PmA kHz V nF V mW
T C mW C W C
D
J
=+
()()
=
=°+ °
()
=°
2 5 3 4 200 35
080 214
70 214 250 124
.••
.
•/
Do not exceed the maximum junction temperature of
125°C.
Figure 6. Recommended Component Placement
R4
INPUT
R5
R1
R3
R2
C1 C2
V
IN
VIAS TO GROUND PLANE
PIEZ0
ACTUATOR
GND
L
3469 F06
OPERATIO
U
Piezo Speaker Driver
+
–
+IN
35
6
2
4
1
8
7
GND
FB
V
CC
SW
LT3469
V
IN
294k
17.4k
C2
0.47µF
35V
V
OUT
1V TO 20V
C1, C2: X5R OR X7R DIELECTRIC
L1: MURATA LQH32CN470
SOUND PRESSURE LEVEL: 87dB AT 750Hz/10V
P-P
/10cm
WITH A 55nF PIEZO SPEAKER. I
VIN
WITH V
IN
= 3.3V:
24mA AT 750Hz/10V
P-P
WITH A 55nF PIEZO SPEAKER
PIEZO
SPEAKER
8nF < C
<
300nF
20k
+
–
16.9k
113k
L1
47µH
–IN OUT
3469 TA01
V
IN
3V TO 6V
INPUT
0V TO 3V
C1
1µF
U
TYPICAL APPLICATIO
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 represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
III +' E Tfifififl lL fa? ’I L7LJEJW
LT3469
8
3469f
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear.com
LINEAR TECHNOLOGY CORPORATION 2003
LT/TP 0304 1K • PRINTED IN USA
RELATED PARTS
PART NUMBER DESCRIPTION COMMENTS
LT1611 550mA I
SW
, 1.4MHz, High Efficiency Inverting DC/DC Converter V
IN
: 0.9V to 10V, V
OUT(MAX)
: 34V, I
Q
: 3mA, I
SD
: <1µA, ThinSOT
LT1616 600mA I
OUT
, 1.4MHz, High Efficiency Step-Down V
IN
: 3.6V to 25V, V
OUT(MIN)
: 1.25V, I
Q
: 1.9mA, I
SD
: <1µA, ThinSOT
DC/DC Converter
LTC1772B 550kHz, Current Mode Step-Down DC/DC Controller V
IN
: 2.5V to 9.8V, V
OUT(MIN)
: 0.8V, I
Q
: 270µA, I
SD
: <8µA, ThinSOT
LT1931/LT1931A 1A I
SW
, 1.2MHz/2.2MHz, High Efficiency Inverting DC/DC V
IN
: 2.6V to 16V, V
OUT(MAX)
: –34V, I
Q
: 4.2mA, I
SD
: <1µA, ThinSOT
Converter
LT1940 (Dual) Dual Output 1.4A I
OUT
, Constant 1.1MHz, High Efficiency V
IN
: 3V to 25V, V
OUT(MIN)
: 1.2V, I
Q
: 2.5mA, I
SD
: <1µA, TSSOP-16E
Step-Down DC/DC Converter
LTC3411 1.25A I
OUT
, 4MHz Synchronous Step-Down DC/DC Converter V
IN
: 2.5V to 5.5V, V
OUT(MIN)
: 0.8V, I
Q
: 60µA, I
SD
: <1µA, MS10, DFN
LT3464 85mA I
SW
, Constant Off-Time, High Efficiency Step-Up DC/DC V
IN
: 2.3V to 10V, V
OUT(MAX)
: 34V, I
Q
: 25µA, I
SD
: <0.5µA, ThinSOT
Converter with Integrated Schottky and Output Disconnect
U
PACKAGE DESCRIPTIO
TS8 Package
8-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1637)
1.50 – 1.75
(NOTE 4)
2.80 BSC
0.22 – 0.36
8 PLCS (NOTE 3)
DATUM ‘A’
0.09 – 0.20
(NOTE 3)
TS8 TSOT-23 0802
2.90 BSC
(NOTE 4)
0.65 BSC
1.95 BSC
0.80 – 0.90
1.00 MAX 0.01 – 0.10
0.20 BSC
0.30 – 0.50 REF
PIN ONE ID
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
3.85 MAX
0.52
MAX 0.65
REF
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
1.4 MIN
2.62 REF
1.22 REF
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193