LTC2930 Datasheet by Analog Devices Inc.

LTLII‘IM TECHNOLOGY L7 LJUW
LTC2930
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TYPICAL APPLICATION
FEATURES
APPLICATIONS
DESCRIPTION
Confi gurable Six Supply
Monitor with Adjustable
Reset Timer, Manual Reset
The LTC
®
2930 is a confi gurable supply monitor for
systems with up to six supply voltages. One of 16 preset or
adjustable voltage monitor combinations can be selected
using an external resistive divider connected to the mode
select pin. The preset voltage thresholds are accurate
to ±1.5% over temperature. The LTC2930 also features
adjustable inputs with a 0.5V nominal threshold.
The reset timeout period is adjustable using an external
capacitor. A reset event may be generated with a manual
reset button on the manual reset input. Tight voltage
threshold accuracy and glitch immunity ensure reliable
reset operation without false triggering. The RST output
is guaranteed to be in the correct state for VCC down to 1V
and may be externally pulled up to an external voltage.
The 52μA supply current makes the LTC2930 ideal for
power conscious systems and it may be confi gured to
monitor fewer than six inputs.
Six Supply Monitor, 5% Threshold
12V, 5V, 3.3V, 1.8V, 1.2V, –5.2V
■ Simultaneously Monitors Six Supplies
■ 16 User Selectable Combinations of
5V, 3.3V, 3V, 2.5V, 1.8V, 1.5V and
± Adjustable Voltage Thresholds
■ Guaranteed ±1.5% Threshold Accuracy
■ Adjustable Reset Timeout
■ Low Supply Current: 52μA
■ Manual Reset Pin
■ Power Supply Glitch Immunity
■ Guaranteed RST for VCC ≥ 1V
■ High Temperature Operation to 125°C
■ 12-Lead 3mm × 3mm DFN Package
■ Desktop and Notebook Computers
■ Multivoltage Systems
■ Telecom Equipment
■ Portable Battery-Powered Equipment
■ Network Servers
■ Automotive
Voltage Threshold Confi guration Table
V1 (V) V2 (V) V3 (V) V4 (V) V5 (V) V6 (V)
5.0 3.3 2.5 1.8 ADJ ADJ
5.0 3.3 2.5 1.5 ADJ ADJ
5.0 3.3 2.5 ADJ ADJ ADJ
5.0 3.3 1.8 ADJ ADJ ADJ
5.0 3.3 1.8 –ADJ ADJ ADJ
5.0 3.3 ADJ ADJ ADJ ADJ
5.0 3.3 ADJ –ADJ ADJ ADJ
5.0 3.0 2.5 ADJ ADJ ADJ
5.0 3.0 1.8 ADJ ADJ ADJ
5.0 3.0 ADJ ADJ ADJ ADJ
3.3 2.5 1.8 1.5 ADJ ADJ
3.3 2.5 1.8 ADJ ADJ ADJ
3.3 2.5 1.8 –ADJ ADJ ADJ
3.3 2.5 1.5 ADJ ADJ ADJ
3.3 2.5 ADJ ADJ ADJ ADJ
3.3 2.5 ADJ –ADJ ADJ ADJ
LTC2930
–5.2V
1.2V
1.8V
3.3V
5V
12V
2930 TA01
CRT
47nF
MANUAL RESET
tRST = 94ms
MR
RST
VREF
VPG GND CRT
V1
V2
V3
V4
V5
V6
SYSTEM
LOGIC
121k
1%
16.2k
1%
86.6k
1%
100k
1%
100k
1%
124k
1%
487k
1%
2150k
1%
0.1μF
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 6967591, 7119714, 7239251.
LTC2930 ‘ F’" 2 2 1 ‘12 £1 1 ‘ a: 74:} 1 1 by El ‘ 1 L9, 767“ L, \ [E 7777‘ 15 LL L7H11EN2
LTC2930
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PIN CONFIGURATIONABSOLUTE MAXIMUM RATINGS
V1, V2, V3, V4, V5, V6, VPG, RST ................ –0.3V to 7V
CRT, VREF, MR ...............................–0.3V to (VCC + 0.3V)
Reference Load Current (IVREF) ..............................±1mA
V4 Input Current (–ADJ Mode) ..............................–1mA
RST Current .........................................................±10mA
Operating Temperature Range
LTC2930C ................................................ 0°C to 70°C
LTC2930I.............................................. –40°C to 85°C
LTC2930H .......................................... –40°C to 125°C
Storage Temperature Range ................... –65°C to 150°C
(Notes 1, 2, 3)
TOP VIEW
DD PACKAGE
12-LEAD (3mm × 3mm) PLASTIC DFN
12
11
13
8
9
10
4
5
3
2
1V6
V2
V4
VREF
VPG
GND
V5
V3
V1
CRT
RST
MR 67
TJMAX = 130°C, θJA = 43°C/W
EXPOSED PAD (PIN 13) IS GND
(PCB CONNECTION OPTIONAL)
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC2930CDD#PBF LTC2930CDD#TRPBF LDMJ 12-Lead 3mm × 3mm DFN 0°C to 70°C
LTC2930IDD#PBF LTC2930IDD#TRPBF LDMJ 12-Lead 3mm × 3mm DFN –40°C to 85°C
LTC2930HDD#PBF LTC2930HDD#TRPBF LDMJ 12-Lead 3mm × 3mm DFN –40°C to 125°C
*The temperature grade is identifi ed 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/
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VCC Minimum Internal Operating Voltage RST in Correct Logic State ●1V
VCCMINP Minimum Required for Mode Selection VCC Rising ●2.4 V
VRT50 5V, 5% Reset Threshold V1 Input Threshold ●4.600 4.675 4.750 V
VRT33 3.3V, 5% Reset Threshold V1, V2 Input Threshold ●3.036 3.086 3.135 V
VRT30 3V, 5% Reset Threshold V2 Input Threshold ●2.760 2.805 2.850 V
VRT25 2.5V, 5% Reset Threshold V2, V3 Input Threshold ●2.300 2.338 2.375 V
VRT18 1.8V, 5% Reset Threshold V3, V4 Input Threshold ●1.656 1.683 1.710 V
VRT15 1.5V, 5% Reset Threshold V3, V4 Input Threshold ●1.380 1.403 1.425 V
VRTA ADJ Reset Threshold V3, V4, V5, V6 Input Threshold ●492.5 500 507.5 mV
VRTAN –ADJ Reset Threshold V4 Input Threshold ●–18 0 18 mV
VREF Reference Voltage VCC ≥ 2.3V, IVREF = ±1mA, CREF ≤ 1000pF ●1.192 1.210 1.228 V
VPG Mode Selection Voltage Range VCC ≥ VCCMINP ●0V
REF V
IVPG VPG Input Current VPG = VREF ●±20 nA
The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TA = 25°C. VCC = 5V, unless otherwise specifi ed. (Note 3)
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SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
IV1 V1 Input Current V1 = 5V, IVREF = 12μA (Note 4) ●52 75 μA
IV2 V2 Input Current V2 = 3.3V ●0.8 2 μA
IV3 V3 Input Current V3 = 2.5V
V3 = 0.55V (ADJ Mode)
●
●
0.52 1.2
±15
μA
nA
IV4 V4 Input Current V4 = 1.8V
V4 = 0.55V (ADJ Mode)
V4 = –0.02V (–ADJ Mode)
●
●
●
0.34 0.8
±15
±15
μA
nA
nA
IV5, IV6 V5, V6 Input Current V5, V6 = 0.55V ●±15 nA
ICRT(UP) CRT Pull-Up Current VCRT = GND ●–1.4 –2 –2.6 μA
ICRT(DN) CRT Pull-Down Current VCRT = 1.3V ●10 20 30 μA
tRST Reset Timeout Period CRT = 1500pF ●234 ms
tUV Vn Undervoltage Detect to RST Vn Less Than Reset Threshold by More
than 1%
150 μs
VOL Voltage Output Low RST ISINK = 3mA, VCC = 3V
ISINK = 100μA, VCC = 1V
●
●
0.15
0.05
0.4
0.3
V
V
VOH Voltage Output High RST (Note 5) ISOURCE = –1μA ●V2-1 V
VIL MR Input Threshold Low VCC = 3.3V to 5.5V ●0.4 V
VIH MR Input Threshold High VCC = 3.3V to 5.5V ●1.6 V
tMRW MR Input Pulse Width VCC = 3.3V ●150 ns
tMRD Manual Reset Propagation Delay VCC = 3.3V, VMR Falling ●0.1 1 μs
IMR MR Pull-Up Current VMR = 1V ●–4 –10 –16 μA
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: All currents into pins are positive, all voltages are referenced to GND
unless otherwise noted.
Note 3: The greater of V1, V2 is the internal supply voltage (VCC).
Note 4: Under static no-fault conditions, V1 will necessarily supply quiescent
current. If at any time V2 is larger than V1, V2 must be capable of supplying
the quiescent current, programming (transient) current and reference load
current.
Note 5: The output pin RST has a diode protected internal pull-up to V2 of
typically 6μA. However, an external pull-up resistor may be used when faster
rise times are required or for VOH voltages greater than V2.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TA = 25°C. VCC = 5V, unless otherwise specifi ed. (Note 3)
Vn Monitor Timing
tRST tRST
tMRW
2930 TD
VRT
Vn
RST
MR
tUV
tMRD
TIMING DIAGRAM
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LTC2930
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TEMPERATURE (°C)
–50
NORMALIZED THRESHOLD VOLTAGES (V/V)
1.005
1.010
1.015
25 75
2930 G01
1.000
0.995
–25 0 50 100 125
0.990
0.985
TEMPERATURE (°C)
–50
THRESHOLD VOLTAGE, VRTAN (mV)
6
12
18
25 75
2930 G02
0
–6
–25 0 50 100 125
–12
–18
TEMPERATURE (°C)
–50
VREF (V)
1.216
1.222
1.228
25 75
2930 G03
1.210
1.204
–25 0 50 100 125
1.198
1.192
TEMPERATURE (°C)
–50
SUPPLY CURRENT, IV1 (μA)
60
65
70
25 75
2930 G04
55
50
–25 0 50 100 125
45
40
V1 = 5V
V2 = 3.3V
V3 = 2.5V
V4 = 1.8V
V5 = V6 = 1V
V4 (mV)
IV4 (A)
2930 G05
–100μ
–10μ
–1μ
–100n
–10n
–1n
–100p
–300
125°C
90°C
25°C
–250 –200 –50 0–100–150
RESET COMPARATOR OVERDRIVE (% OF VRTX)
0.1
0
TYPICAL TRANSIENT DURATION (μs)
200
250
300
1 10 100
2930 G06
150
100
50
TA = 25°C
RESET OCCURS ABOVE CURVE
RESET COMPARATOR OVERDRIVE (% OF VRTX)
0.1
0
TYPICAL TRANSIENT DURATION (μs)
300
375
450
1 10 100
2930 G07
225
150
75
TA = 25°C
RESET OCCURS ABOVE CURVE
V1 (V)
0
0
RST OUTPUT VOLTAGE (V)
1
2
3
4
5
6
1234
2930 G08
5
TA = 25°C
10k PULL-UP FROM RST TO V1
TEMPERATURE (°C)
–50
1
RESET TIMEOUT PERIOD, tRST (ms)
2
3
4
5
–25 0 25 50
2930 G09
75 100 125
CRT = 1500pF
(SILVER MICA)
TYPICAL PERFORMANCE CHARACTERISTICS
Normalized Threshold Voltages
vs Temperature
–ADJ Threshold Voltage
vs Temperature VREF vs Temperature
Supply Current vs Temperature
Transient Duration vs Comparator
Overdrive (V1,V2)
Transient Duration vs Comparator
Overdrive (V3, V4, V5, V6)
RST Output Voltage
vs V1, VPG = GND
I(V4) vs V4 in Negative
Adjust Mode
Reset Timeout Period
vs Temperature
LTC2930 \ \ \ L7 LJUW
LTC2930
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CRT (F)
RESET TIMEOUT PERIOD tRST (s)
2930 G10
10
1
100m
10m
1m
100μ
10μ10p 100p 1n 100n 1μ10n
TA = 25°C
V1 OR V2 (V)
0
ISINK (mA)
9
12
15
4
2930 G11
6
3
01235
TA = 25°C
VOL = 0.4V
VOL = 0.2V
ISINK (mA)
0
VOL (mV)
300
400
500
8
2930 G12
200
100
024610
V1 = 5V
V2 = 3V 125°C
85°C
25°C
–40°C
V2 (V)
2.0
0
PULL-UP CURRENT (μA)
3
6
9
12
18
2.5 3.0 3.5 4.0
2930 G13
4.5 5.0
15
TA = 25°C
VRT25
VRT30
VRT33
TYPICAL PERFORMANCE CHARACTERISTICS
Reset Timeout Period vs CRT
Voltage Output Low
vs Output Sink Current (RST)RST Pull-Up Current vs V2
ISINK vs Supply Voltage (RST)
PIN FUNCTIONS
V5 (Pin 1): Adjustable Voltage Input 5. High impedance
comparator input with 0.5V typical threshold. See
Applications Information for details. Tie to V1 if unused.
V3 (Pin 2): Voltage Input 3. Select from 2.5V, 1.8V, 1.5V,
or ADJ. See Applications Information for details. Tie to
V1 if unused.
V1 (Pin 3): Voltage Input 1. Select from 5V or 3.3V. See
Applications Information for details. The greater of V1 or
V2 is also VCC for the device. Bypass this pin to ground
with a 0.1μF (or greater) capacitor.
CRT (Pin 4): Reset Timeout Capacitor. Attach an external
capacitor (CRT) to GND to set a reset timeout of 2ms/nF.
Leaving the pin open generates a minimum delay of
approximately 25μs. A 47nF capacitor generates a 94ms
reset delay time.
RST (Pin 5): Reset Output. Logic output with weak 6μA
pull-up to V2. Pulls low when any voltage input is below
the reset threshold and held low for the confi gured delay
time after all voltage inputs are above threshold. Use an
external pull-up to pull greater than V2. Leave open if
unused.
LTC2930 3—D L7LJCUEN2
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PIN FUNCTIONS
A/D
BUFFER
1.210V
8
VPG
3
V1
11
V2
2
V3
10
V4
1
V5
12
V6
9
VREF
4
0.5V
4
2931 BD
BANDGAP
REFERENCE
ADJUSTABLE
RESET PULSE
GENERATOR
POWER
DETECT
V1
V2
VCC
4CRT
6MR
CRT
VCC
VCC
22μA
RESISTIVE
DIVIDER
MATRIX
4
–
+
–
+
–
+
7
GND
V2
6μA
2μA
5
RST
CMP1-4
CMP5
CMP6
10μA
MR (Pin 6): Manual Reset Input. A logic low on this
pin pulls RST low. When the MR pin returns high, RST
returns high after the confi gured reset timeout if all six
voltage inputs are above threshold. A weak internal pull-up
allows the pin to be left open for normal monitor operation.
When using a switch, the switch is debounced through
the reset circuitry using the delay provided by the CRT
timing capacitor.
GND (Pin 7): Ground.
VPG (Pin 8): Threshold Select Input. Connect to an external
1% resistive divider between VREF and GND to select 1
of 16 combinations and/or ±adjustable voltage thresholds
(See Table 1). Do not add capacitance on the VPG pin.
VREF (Pin 9): Buffered Reference Voltage Output. A
1.210V nominal reference used for the mode selection
voltage (VPG) and for the offset of negative adjustable
applications. The buffered reference can source and sink
up to 1mA. The reference can drive a bypass capacitor of
up to 1000pF without oscillation.
V4 (Pin 10): Voltage Input 4. Select from 1.8V, 1.5V, ADJ
or –ADJ. See Applications Information for details. Tie to
V1 if unused.
V2 (Pin 11): Voltage Input 2. Select from 3.3V, 3V or 2.5V.
See Applications Information for details. The greater of V1,
V2 is also VCC for the device. Bypass this pin to ground
with a 0.1μF (or greater) capacitor. RST is weakly pulled
up to V2.
V6 (Pin 12): Adjustable Voltage Input 6. High impedance
comparator input with 0.5V typical threshold. See
Applications Information for details. Tie to V1 if unused.
Exposed Pad (Pin 13): Exposed pad may be left open or
connected to device ground.
BLOCK DIAGRAM
LTC2930 L7 LJUW
LTC2930
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APPLICATIONS INFORMATION
Supply Monitoring
The LTC2930 is a low power, high accuracy confi gurable six
supply monitoring circuit with a common reset output. An
external capacitor sets the reset timeout period. An external
resistive divider between VREF, VPG and GND selects 1 of
16 possible input voltage monitor combinations. All six volt-
age inputs must be above their predetermined thresholds
for the reset not to be activated. The LTC2930 asserts the
reset output during power-up, power-down and brownout
conditions on any one of the voltage inputs.
Power-Up
The greater of V1 and V2 serves as the internal supply
voltage (VCC). On power-up, VCC powers the drive circuits
for the RST pin. This ensures that the RST output will be
low as soon as either V1 or V2 reaches 1V. The RST output
remains low until the part is confi gured. Once voltage
thresholds are set, if any of the supply monitor inputs is
below its confi gured threshold, RST will be a logic low.
Once all the monitor inputs rise above their thresholds,
an internal timer is started and RST is released after the
delay time. If VCC < (V3 – 1.0V) and VCC < 2.4V, the V3
input impedance will be low (10kΩ typical).
Threshold Accuracy
Consider a 5V system with ±5% tolerance. The 5V supply
may vary between 4.75V to 5.25V. System ICs powered by
this supply must operate reliably within this band (and a
little more as explained below). A perfectly accurate su-
Table 1. Voltage Threshold Modes*
MODE V1 (V) V2 (V) V3 (V) V4 (V) R1 (kΩ) R2 (kΩ)
VPG
VREF
0 5.0 3.3 ADJ ADJ Open Short 0.000
1 5.0 3.3 ADJ –ADJ 93.1 9.53 0.094
2 3.3 2.5 ADJ ADJ 86.6 16.2 0.156
3 3.3 2.5 ADJ –ADJ 78.7 22.1 0.219
4 3.3 2.5 1.5 ADJ 71.5 28.0 0.281
5 5.0 3.3 2.5 ADJ 66.5 34.8 0.344
6 5.0 3.3 2.5 1.8 59.0 40.2 0.406
7 5.0 3.3 2.5 1.5 53.6 47.5 0.469
8 5.0 3.0 2.5 ADJ 47.5 53.6 0.531
9 5.0 3.0 ADJ ADJ 40.2 59.0 0.594
10 3.3 2.5 1.8 1.5 34.8 66.5 0.656
11 3.3 2.5 1.8 ADJ 28.0 71.5 0.719
12 3.3 2.5 1.8 –ADJ 22.1 78.7 0.781
13 5.0 3.3 1.8 –ADJ 16.2 86.6 0.844
14 5.0 3.3 1.8 ADJ 9.53 93.1 0.906
15 5.0 3.0 1.8 ADJ Short Open 1.000
*V5 and V6 are always adjustable (ADJ).
pervisor for this supply generates a reset at exactly 4.75V,
however no supervisor is this perfect. The actual reset
threshold of a supervisor varies over a specifi ed band;
the LTC2930 varies ±1.5% around its nominal threshold
voltage (see Figure 1) over temperature.
The reset threshold band and the power supply tolerance
bands should not overlap. This prevents false or nuisance
resets when the power supply is actually within its speci-
fi ed tolerance band.
The LTC2930 has a ±1.5% reset threshold accuracy, so a
“5%” threshold is typically set to 6.5% below the nominal
input voltage. Therefore, a typical 5V, “5%” threshold is
4.675V. The threshold is guaranteed to lie in the band be-
tween 4.750V and 4.600V over temperature. The powered
system must work reliably down to the low end of the
threshold band, or risk malfunction before a reset signal
is properly issued.
A less accurate supervisor increases the required system
voltage margin and increases the probability of system
malfunction. The LTC2930 ±1.5% specifi cation improves
the reliability of the system over supervisors with wider
threshold tolerances.
5V
4.75V
4.675V
±1.5%
THRESHOLD
BAND
4.6V
NOMINAL
SUPPLY
VOLTAGE
SUPPLY TOLERANCE
MINIMUM
RELIABLE
SYSTEM
VOLTAGE
IDEAL
SUPERVISOR
THRESHOLD
REGION OF POTENTIAL MALFUNCTION
–5%
–6.5%
–8%
Figure 1. 1.5% Threshold Accuracy Improves System Reliability
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APPLICATIONS INFORMATION
Monitor Confi guration
Select the LTC2930 input voltage combination by placing
the recommended resistive divider from VREF to GND and
connecting the tap point to VPG, as shown in Figure 2.
Table 1 offers recommended 1% resistor values for each
of the 16 modes. The last column in Table 1 specifi es
optimum VPG/VREF ratios (± 0.01), when confi guring with
a ratiometric DAC.
At power-up, once V1 or V2 reaches 2.4V, the monitor
enters a setup period of approximately 150μs. During the
setup time, the voltage on the VPG pin is sampled and the
monitor is confi gured to the desired input combination. The
comparators are enabled and supply monitoring begins.
Do not add capacitance to the VPG pin.
Figure 3. Setting the Positive Adjustable Trip Point
+
–0.5V
2930 F03
V3, V4, V5 OR V6
VTRIP
R3
1%
R4
1%
LTC2930
2930 F04
V4
VREF
VTRIP
R4
1%
R3
1%
LTC2930
Figure 4. Setting the Negative Adjustable Trip Point
VSUPPLY (V) VTRIP (V) R3 (kΩ) R4 (kΩ)
12 11.25 2150 100
10 9.4 1780 100
8 7.5 1400 100
7.5 7 1300 100
6 5.6 1020 100
5 4.725 845 100
3.3 3.055 511 100
3 2.82 464 100
2.5 2.325 365 100
1.8 1.685 237 100
1.5 1.410 182 100
1.2 1.120 124 100
1 0.933 86.6 100
0.9 0.840 68.1 100
*See Figure 3.
Table 2. Suggested 1% Resistor Values for the ADJ Inputs
VSUPPLY (V) VTRIP (V) R3 (kΩ) R4 (kΩ)
–2 –1.87 187 121
–5 –4.64 464 121
–5.2 –4.87 487 121
–10 –9.31 931 121
–12 –11.30 1130 121
*See Figure 4.
Table 3. Suggested 1% Resistor Values for the –ADJ Inputs
VTRIP =0.5V • 1+R3
R4
In the negative adjustable mode, the reference level on the
V4 comparator is connected to ground (Figure 4). The tap
point on an external resistive divider, connected between
the negative voltage being sensed and the VREF pin, is
R1
1%
R2
1%
2930 F02
VREF
VPG
GND
LTC2930
Figure 2. Mode Selection
Using The Adjustable Thresholds
The reference inputs on the V3 and/or V4 comparators
are set to 0.5V when the positive adjustable modes are
selected (Figure 3). The reference inputs on the V5 and V6
comparators are always set to 0.5V. The tap point on an
external resistive divider, connected between the positive
voltage being sensed and ground, is connected to the high
impedance, adjustable inputs (V3, V4, V5, V6). Calculate
the trip voltage from:
1.210V RST L7 LJUW LTC2930
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APPLICATIONS INFORMATION
Leaving the CRT pin unconnected generates a minimum
reset timeout of approximately 25μs. Maximum reset
timeout is limited by the largest available low leakage
capacitor. The accuracy of the timeout period is affected
by capacitor leakage (the nominal charging current is 2μA)
and capacitor tolerance. A low leakage ceramic capacitor
is recommended.
OR-ed System Reset
In Figure 5, two LTC2930s are confi gured to monitor 11
supply voltages simultaneously. The unused adjustable
input pin is tied to the V1 input. The open-drain RST
outputs are OR-tied and pulled up to 5V through a 10kΩ
resistor. RST pulls high 94ms after all the inputs are above
the threshold voltages. Should a reset event occur on ei-
ther LTC2930, both RST outputs pull low. Similarly, if the
manual reset pushbutton is pressed, both RST outputs
also pull low.
Using a Pushbutton On/Off Controller with the
LTC2930
In Figure 6, the LTC2950-1 pushbutton controller powers
a system on and off. The system starts after the pushbut-
ton is pressed, which brings the LTM4600’s RUN pin high.
Subsequently, the LTM4600 generates a 5V output which
applies power to each of the four DC/DC converters.
The LTC2930 is confi gured to mode 13 (see Table 1).
The voltages monitored are 5V, 3.3V, 1.8V, –5.2V, 2.5V
and 12V.
If the KILL input is not driven high within 512ms of a valid
turn-on event, EN pulls low shutting down the system. If
the external 12V supply drops below 9.6V, EN pulls low,
powering down the LTM4600 and subsequent circuitry.
An external 4.7nF capacitor sets the 9.4ms reset timeout
period. Therefore, 9.4ms after the last supply is above
threshold, RST pulls high. The reset timing capacitor
must be chosen to keep the reset timeout period below
512ms. Otherwise, the KILL timer will expire and shut
down the system.
Pressing the pushbutton after the system is powered initi-
ates the power off sequence. An interrupt is set, bringing
EN low immediately and disabling the LTM4600.
connected to the high impedance adjustable input (V4).
VREF provides the necessary level shift required to operate
at ground. The negative trip voltage is calculated from:
VTRIP =−VREF •R3
R4;V
REF =1.210
V
Nominal
In a negative adjustable application, the minimum value for
R4 is limited by the sourcing capability of VREF (±1mA).
With no other load on VREF, R4 (minimum) is:
1.210V
1m A =1.210k
Tables 2 and 3 offer suggested 1% resistor values for vari-
ous positive and negative supply adjustable applications
assuming 5% monitor thresholds.
Although all six supply monitor comparators have built-
in glitch immunity, bypass capacitors on V1 and V2 are
recommended because the greater of V1 or V2 is also the
VCC for the device. Filter capacitors on the V3, V4, V5 and
V6 inputs are allowed.
Power-Down
On power-down, once any of the monitor inputs drops
below its threshold, RST is held at a logic low. A logic low
of 0.4V is guaranteed until both V1 and V2 drop below
1V. If the bandgap reference becomes invalid (VCC < 2V
typical), the LTC2930 will enter the 150μs setup period
when VCC rises above 2.4V max.
Selecting the Reset Timing Capacitor
The reset timeout period is adjustable in order to
accommodate a variety of microprocessor applications.
The reset timeout period, tRST
, is adjusted by connecting
a capacitor, CRT
, between the CRT pin and ground. The
value of this capacitor is determined by:
CRT =tRST
2MΩ=500 pF / ms
[]
•t
RST
LTC2930 L7LJCUEN2
LTC2930
10
2930fa
APPLICATIONS INFORMATION
Figure 5. OR-ed System Reset
LTC2930
1V
0.9V
–5.2V
1.8V
3.3V
5V
CRT
47nF
MR
RST
VREF
VPG GND CRT
V1
V2
V3
V4
V5
V6
121k
1%
R1A
16.2k
1%
R2A
86.6k
1%
100k
1%
10k**
10k
100k
1%
487k
1%
86.6k
1%
68.1k
1%
0.1μF
LTC2930
6V
8V
12V
3V
5V
2930 F05
CRT
47nF
MANUAL RESET
PUSHBUTTON
tRST = 94ms
**OPTIONAL FOR EXTENDED ESD TOLERANCE
MR
RST RESET
VREF
VPG GND CRT
V1
V2
V3
V4
V5
V6
100k
1%
R1B
40.2k
1%
R2B
59k
1%
100k
1%
100k
1%
2150k
1%
1400k
1%
1020k
1%
0.1μF
Figure 6. Using a Pushbutton On/Off Controller with the LTC2930
SYSTEM RESET
LTC2930
12V (9.6V THRESHOLD)
2.5V
–5.2V
1.8V
3.3V
5V
2930 F06
365k
1%
487k
1%
5V
tRST = 9.4ms
4.7nF
0.1μF
RST
MR
VPG GNDCRT
V1
V2
V3
V4
V5
V6
VREF
SYSTEM
LOGIC
LT3028
VIN 3.3V
VOUT
SHDN
LTM4600
VIN
VOUT
RUN
LT3028
VIN 1.8V
VOUT
SHDN
LTC3704
VIN –5.2V
VOUT
RUN/UVLO
LT3028
VIN 2.5V
VOUT
SHDN
10k
100k
1%
121k
1%
1500k
1%
100k
1%
R1
16.2k
1%
R2
86.6k
1%
LTC2950-1
VIN INT
PB KILL
EN
10k
LTC2930 \ iii‘iiiisuuwm ‘ (asmESJ \ F 0751mm i + ’[IUL7’UEI5 r *5 L7 LJUW
LTC2930
11
2930fa
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.
PACKAGE DESCRIPTION
3.00 p0.10
(4 SIDES)
NOTE:
1. DRAWING IS NOT A JEDEC PACKAGE OUTLINE
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD AND TIE BARS SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
0.40 p 0.10
BOTTOM VIEW—EXPOSED PAD
1.65 p 0.10
0.75 p0.05
R = 0.115
TYP
16
127
PIN 1
TOP MARK
(SEE NOTE 6)
0.200 REF
0.00 – 0.05
(DD12) DFN 0106 REV A
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
0.23 p 0.05
0.25 p 0.05
2.25 REF
2.38 p0.05
1.65 p0.05
2.10 p0.05
0.70 p0.05
3.50 p0.05
PACKAGE
OUTLINE
PIN 1 NOTCH
R = 0.20 OR
0.25 s 45o
CHAMFER
2.38 p0.10
2.25 REF
0.45 BSC
0.45 BSC
DD Package
12-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1725 Rev A)
LTC2930 ‘sv ‘zv —||— L7LJ1‘JEN2
LTC2930
12
2930fa
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2008
LT 0308 REV A • PRINTED IN USA
TYPICAL APPLICATION
PART NUMBER DESCRIPTION COMMENTS
LTC1326 Micropower Triple Supply Monitor for 5V/2.5V, 3.3V and ADJ 4.725V, 3.118V, 1V Threshold (±0.75%) and ADJ
LTC1728 Micropower Triple Supply Monitor with Open-Drain Reset 5-Lead SOT-23 Package
LTC2900 Programmable Quad Supply Monitor Adjustable Reset, 10-Lead MSOP and DFN Packages
LTC2901 Programmable Quad Supply Monitor Adjustable Reset and Watchdog Timer
LTC2902 Programmable Quad Supply Monitor Adjustable Reset and Tolerance (5%, 7.5%, 10%, or 12.5%)
LTC2903 Precision Quad Supply Monitor 6-Lead SOT-23 Package
LTC2904-LTC2907 Three-State Programmable Precision Dual Supply Monitor 8-Lead SOT-23 and DFN Packages
LTC2908 Precision Six Supply Monitor (Four Fixed & Two Adjustable) 8-Lead TSOT-23 and DFN Packages
LTC2909 Precision Triple/Dual Input UV, OV and Negative Voltage Monitor Shunt Regulated VCC Pin, Adjustable Threshold and Reset,
8-Lead SOT-23 and DFN Packages
LTC2910 Precision Octal Positive/Negative Voltage Supply Monitor 16-Lead SSOP and 5mm × 3mm DFN Packages,
H-Grade Temperature Range
LTC2912-LTC2914 Single/Dual/Quad UV and OV Voltage Monitors Separate VCC Pin, Adjustable Reset Timer,
H-Grade Temperature Range
LTC2915-LTC2918 Single Supply Monitor with 27 Pin-Selectable Thresholds Manual Reset, Watchdog, TSOT-8/MSOP-10 and 3mm × 2mm
DFN Packages, H-Grade Temperature Range
LTC2928 Quad Power Supply Sequencer and Supervisor Easily Confi gure Power Management without Software,
36-Lead 5mm × 7mm QFN and SSOP Packages
LTC2931 Confi gurable Six Supply Monitor with Individual Comparator
Outputs
Adjustable Reset and Watchdog Timers, TSSOP-20 Package
LTC2932 Confi gurable Six Supply Monitor with Individual Comparator
Outputs
Adjustable Reset Timer and Tolerance, TSSOP-20 Package,
Pin-Selectable Tolerance (5%, 7.5%, 10%, or 12.5%),
Reset Disable for Margining
RELATED PARTS
Five Supply Monitor, 5% Threshold (3.3V, 1.5V, 1.2V, 1V, 0.9V)
LTC2930
0.9V
1V
1.2V
1.5V
3.3V
CRT
47nF
MR
RST
VREF
VPG GND CRT
V1
V2
V3
V4
V5
V6
R1
71.5k
1%
R2
28k
1%
100k
1%
100k
1%
100k
1%
124k
1%
86.6k
1%
68.1k
1%
0.1μF
PUSHBUTTON
RESET
SYSTEM RESET
tRST = 94ms
2930 TA02