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FEATURES

LTC2932 Configurable Six Supply Monitor with Adjustable Reset Timer and Supply Tolerance DESCRIPTION
The LTC(R)2932 is a configurable 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 digitally configurable to 5%, 7.5%, 10%, or 12.5% below the nominal operating voltage. The LTC2932 also features adjustable inputs with a 0.5V nominal threshold. All six open-drain voltage comparator outputs are connected to separate pins for individual supply monitoring. The reset timeout period is adjustable using an external capacitor. The RST output is guaranteed to be in the correct state for VCC down to 1V and may be disabled during supply margin testing. Each status output has a weak internal pull-up and may be externally pulled up to an external voltage. The 52A supply current makes the LTC2932 ideal for power conscious systems and the part may be configured to monitor less than six inputs.
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.

Simultaneously Monitors Six Supplies 16 User Selectable Combinations of 5V, 3.3V, 3V, 2.5V, 1.8V, 1.5V and Adjustable Voltage Thresholds Guaranteed Threshold Accuracy: 1.5% Selectable Supply Tolerances: 5%, 7.5%, 10%, 12.5% Below Monitored Voltage Reset Disable Pin for Margining Applications Low Supply Current: 52A Power Supply Glitch Immunity Guaranteed RST for VCC 1V High Temperature Operation to 125C 20-Lead TSSOP Package
APPLICATIONS

Desktop and Notebook Computers Multivoltage Systems Telecom Equipment Portable Battery-Powered Equipment Network Servers Automotive
TYPICAL APPLICATION
Six Supply Monitor 12V (ADJ), 5V, 3.3V, 2.5V, 1.8V, 1.2V (ADJ)
12V 5V 3.3V 2.5V 1.8V 1.2V 10k 2150k 1% 124k 1% COMP1 COMP2 COMP3 COMP4 COMP5 V1 V2 0.1F 0.1F 100k 1% 100k 1% R1 59k 1% R2 40.2k 1% V3 V4 V5 V6 VREF VPG GND T0 T1 CRT RST
2932 TA01
Voltage Threshold Configuration Table
V1 (V) 5 5
SYSTEM LOGIC
V2 (V) 3.3 3.3 3.3 3.3 3.3 3.3 3.3 3 3 3 2.5 2.5 2.5 2.5 2.5 2.5
V3 (V) 2.5 2.5 2.5 1.8 1.8 ADJ ADJ 2.5 1.8 ADJ 1.8 1.8 1.8 1.5 ADJ ADJ
V4 (V) 1.8 1.5 ADJ ADJ -ADJ ADJ -ADJ ADJ ADJ ADJ 1.5 ADJ -ADJ ADJ ADJ -ADJ
V5 (V) ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ
V6 (V) ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ ADJ
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5 5 5 5 5 5 5 5
POWER GOOD COMP6
LTC2932 RDIS
3.3 3.3 3.3 3.3 3.3 3.3
tRST = 94ms CRT 47nF
1
LTC2932 ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2, 3)
PIN CONFIGURATION
TOP VIEW COMP5 V5 COMP3 COMP1 V3 V1 CRT RST T0 1 2 3 4 5 6 7 8 9 20 COMP6 19 V6 18 COMP2 17 COMP4 16 V2 15 V4 14 VREF 13 VPG 12 GND 11 T1
V1, V2, V3, V4, V5, V6, VPG ........................ -0.3V to 7V RST, COMP1-6, T0, T1................................. -0.3V to 7V CRT, VREF RDIS ............................-0.3V to (VCC + 0.3V) , Reference Load Current (IVREF) ..............................1mA V4 Input Current (-ADJ Mode) ..............................-1mA RST, COMP1-6 Currents ......................................10mA Operating Temperature Range LTC2932C ................................................ 0C to 70C LTC2932I..............................................- 40C to 85C LTC2932H ..........................................- 40C to 125C Storage Temperature Range...................- 65C to 150C Lead Temperature (Soldering, 10 sec) .................. 300C
RDIS 10
F PACKAGE 20-LEAD PLASTIC TSSOP TJMAX = 130C, JA = 90C/W
ORDER INFORMATION
LEAD FREE FINISH LTC2932F#PBF LTC2932F#PBF LTC2932F#PBF TAPE AND REEL LTC2932CF#TRPBF LTC2932IF#TRPBF LTC2932HF#TRPBF PART MARKING* LTC2932F LTC2932F LTC2932F PACKAGE DESCRIPTION 20-Lead Plastic TSSOP 20-Lead Plastic TSSOP 20-Lead Plastic TSSOP TEMPERATURE RANGE 0C to 70C -40C to 85C -40C to 125C
Consult LTC Marketing for information on non-standard lead based finish parts. *Temperature grades are 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/
ELECTRICAL CHARACTERISTICS
SYMBOL VCC VCCMINP VCCMINC VRT50 PARAMETER Minimum Internal Operating Voltage Minimum Required for Mode Selection Minimum Required for Comparators 5V, 5% Reset Threshold 5V, 7.5% Reset Threshold 5V, 10% Reset Threshold 5V, 12.5% Reset Threshold 3.3V, 5% Reset Threshold 3.3V, 7.5% Reset Threshold 3.3V, 10% Reset Threshold 3.3V, 12.5% Reset Threshold 3V, 5% Reset Threshold 3V, 7.5% Reset Threshold 3V, 10% Reset Threshold 3V, 12.5% Reset Threshold
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 5V, unless otherwise specified. (Note 3)
CONDITIONS RST, COMPn in Correct Logic State VCC Rising VCC Falling V1 Input Threshold

MIN
TYP
MAX 1 2.4 2.3
UNITS V V V V V V V V V V V V V V V
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4.600 4.475 4.350 4.225 3.036 2.954 2.871 2.789 2.760 2.685 2.610 2.535
4.675 4.550 4.425 4.300 3.086 3.003 2.921 2.838 2.805 2.730 2.655 2.580
4.750 4.625 4.500 4.375 3.135 3.053 2.970 2.888 2.850 2.775 2.700 2.625
VRT33
V1, V2 Input Threshold
VRT30
V2 Input Threshold
2
LTC2932 ELECTRICAL CHARACTERISTICS
SYMBOL VRT25 PARAMETER 2.5V, 5% Reset Threshold 2.5V, 7.5% Reset Threshold 2.5V, 10% Reset Threshold 2.5V, 12.5% Reset Threshold 1.8V, 5% Reset Threshold 1.8V, 7.5% Reset Threshold 1.8V, 10% Reset Threshold 1.8V, 12.5% Reset Threshold 1.5V, 5% Reset Threshold 1.5V, 7.5% Reset Threshold 1.5V, 10% Reset Threshold 1.5V, 12.5% Reset Threshold ADJ, 5% Reset Threshold ADJ, 7.5% Reset Threshold ADJ, 10% Reset Threshold ADJ, 12.5% Reset Threshold -ADJ Reset Threshold Reference Voltage
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 5V, unless otherwise specified. (Note 3)
CONDITIONS V2, V3 Input Threshold

MIN 2.300 2.238 2.175 2.113 1.656 1.611 1.566 1.521 1.380 1.343 1.305 1.268 492.5 479.4 466.3 453.1 -18 1.192 1.160 1.128 1.096 0
TYP 2.338 2.275 2.213 2.150 1.683 1.638 1.593 1.548 1.403 1.365 1.328 1.290 500.0 486.6 473.3 459.9 0 1.210 1.178 1.146 1.113
MAX 2.375 2.313 2.250 2.188 1.710 1.665 1.620 1.575 1.425 1.388 1.350 1.313 507.5 494 480.4 466.8 18 1.228 1.195 1.163 1.130 VREF 20
UNITS V V V V V V V V V V V V mV mV mV mV mV V V V V V nA A A A nA A nA nA nA A A A ms s
VRT18
V3, V4 Input Threshold
VRT15
V3, V4 Input Threshold
VRTA
V3, V4, V5, V6 Input Threshold
VRTAN VREF
V4 Input Threshold VCC 2.3V, IVREF = 1mA, CREF 1000pF T0 Low, T1 Low T0 Low, T1 High T0 High, T1 Low T0 High, T1 High VCC VCCMINP VPG = VREF V1 = 5V, IVREF = 12A (Note 4) V2 = 3.3V V3 = 2.5V V3 = 0.55V (ADJ Mode) V4 = 1.8V V4 = 0.55V (ADJ Mode) V4 = -0.02V (-ADJ Mode) V5, V6 = 0.55V VCRT = GND VCRT = 1.3V VCOMPn = GND CRT = 1500pF Vn Less Than Reset Threshold by More than 1% ISINK = 3mA, VCC = 3V ISINK = 100A, VCC = 1V ISOURCE = -1A
VPG IVPG IV1 IV2 IV3 IV4
Mode Selection Voltage Range VPG Input Current V1 Input Current V2 Input Current V3 Input Current V4 Input Current
52 0.8 0.52 0.34
75 2 1.2 15 0.8 15 15 15 -2.6 30 -12 4
IV5, IV6 ICRT(UP) ICRT(DN) ICOMPn tRST tUV VOL VOH
V5, V6 Input Current CRT Pull-Up Current CRT Pull-Down Current COMPn Pull-Up Current Reset Timeout Period Vn Undervoltage Detect to RST or COMPn Voltage Output Low RST, COMPn Voltage Output High RST, COMPn (Note 5)
-1.4 10 -2 2
-2 20 -6 3 150

0.15 0.05 V2-1
0.4 0.3
V V V
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LTC2932 ELECTRICAL CHARACTERISTICS
SYMBOL VIL VIH IINTOL VIL VIH IRDIS PARAMETER T0, T1 Low Level Input Voltage T0, T1 High Level Input Voltage T0, T1 Input Current RDIS Input Threshold Low RDIS Input Threshold High RDIS Pull-Up Current Digital Inputs T0, T1, RDIS VCC = 3.3V to 5.5V VCC = 3.3V to 5.5V T0, T1 = 2V VCC = 3.3V to 5.5V VCC = 3.3V to 5.5V VRDIS = 1V

The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VCC = 5V, unless otherwise specified. (Note 3)
CONDITIONS MIN TYP MAX 0.3VCC 0.7VCC 0.1 1.6 -4 -10 -16 1 0.4 UNITS V V A V V A
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 pins RST and COMPn have diode protected internal pull-ups to V2 of typically 6A. However, external pull-up resistors may be used when faster rise times are required or for VOH voltages greater than V2.
TIMING DIAGRAM
Vn Monitor Timing
Vn VRT tUV RST tRST
2932 TD
COMPn
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LTC2932 TYPICAL PERFORMANCE CHARACTERISTICS
Normalized Threshold Voltages vs Temperature
NORMALIZED THRESHOLD VOLTAGES (V/V) 1.015 1.010 1.005 1.000 0.995 0.990 0.985 -50 -25 THRESHOLD VOLTAGE, VRTAN (mV) 18 12 6 0 -6 -12 -18 -50 -25
-ADJ Threshold Voltage vs Temperature
1.228 1.222 1.216 VREF (V) 1.210 1.204 1.198
VREF vs Temperature
50 25 75 0 TEMPERATURE (C)
100
125
50 25 75 0 TEMPERATURE (C)
100
125
1.192 -50 -25
50 75 25 0 TEMPERATURE (C)
100
125
2932 G01
2932 G02
2932 G03
Supply Current vs Temperature
70 V1 = 5V V2 = 3.3V 65 V3 = 2.5V V4 = 1.8V V5 = V6 = 1V 60 IV4 (A) 55 50 45 40 -50 -25 -100 -10 -1 -100n -10n -1n
I(V4) vs V4 in Negative Adjust Mode
300 TYPICAL TRANSIENT DURATION (s) 250 200
Transient Duration vs Comparator Overdrive (V1,V2)
TA = 25C
SUPPLY CURRENT, IV1 (A)
125C
RESET OCCURS ABOVE CURVE 150 100 50 0 0.1 1 10 100 RESET COMPARATOR OVERDRIVE (% OF VRTX)
2932 G06
90C
25C 50 25 75 0 TEMPERATURE (C) 100 125 -100p -300 -250 -200 -150 -100 V4 (mV) -50 0
2932 G05 2932 G04
Transient Duration vs Comparator Overdrive (V3, V4, V5, V6)
450 TYPICAL TRANSIENT DURATION (s) 375 RST OUTPUT VOLTAGE (V) 300 RESET OCCURS ABOVE CURVE 225 150 75 0 0.1 1 10 100 RESET COMPARATOR OVERDRIVE (% OF VRTX)
2932 G07
RST Output Voltage vs V1, VPG = GND
6 5 4 3 2 1 0 0 1 2 V1 (V)
2932 G08
Reset Timeout Period vs Temperature
5 RESET TIMEOUT PERIOD, tRST (ms) CRT = 1500pF (SILVER MICA)
TA = 25C
TA = 25C 10k PULL-UP FROM RST TO V1
4
3
2
3
4
5
1 -50
-25
75 0 25 50 TEMPERATURE (C)
100
125
2932 G09
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LTC2932 TYPICAL PERFORMANCE CHARACTERISTICS
Reset Timeout Period vs CRT
10 1 RESET TIMEOUT PERIOD tRST (s) 100m ISINK (mA) 9 VOL = 0.2V 6 10m 1m 100 10 10p 3 100 TA = 25C 15
ISINK vs Supply Voltage (RST, COMPn)
TA = 25C 500
Voltage Output Low vs Output Sink Current (RST, COMPn)
V1 = 5V V2 = 3V 125C 85C VOL (mV) 300 25C 200 -40C
12 VOL = 0.4V
400
100p
1n 10n CRT (F)
100n
1
2932 G10
0
0
1
3 2 V1 OR V2 (V)
0 4 5
2932 G11
0
2
6 4 ISINK (mA)
8
10
2932 G12
COMPn Pull-Up Current vs V2
18 15 PULL-UP CURRENT (A) 12 9 6 3 0 1 2 3 V2 (V) 4 5
2932 G13
COMPn Propagation Delay vs Input Overdrive Above Threshold
250 COMPn PROPAGATION DELAY (s) TA = 25C 18 15 PULL-UP CURRENT (A) 12 9 6
RST Pull-Up Current vs V2
TA = 25C
TA = 25C COMPn = GND
200
150 V1, V2 100 V3, V4, V5, V6
VRT33 VRT30
50
3 VRT25 0
0
1000 10 100 INPUT OVERDRIVE ABOVE THRESHOLD (mV)
2932 G14
2.0
2.5
3.0
3.5 V2 (V)
4.0
4.5
5.0
2932 G15
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LTC2932 PIN FUNCTIONS
COMP5 (Pin 1): Comparator Output 5. Real-time logic output with weak 6A pull-up to V2. Pulls high when V5 is above reset threshold. May be pulled greater than V2 using external pull-up. Leave open if unused. V5 (Pin 2): Adjustable Voltage Input 5. High impedance comparator input with 0.5V typical threshold. See Applications Information for details. Tie to V1 if unused. COMP3 (Pin 3): Comparator Output 3. Real-time logic output with weak 6A pull-up to V2. Pulls high when V3 is above reset threshold. May be pulled greater than V2 using external pull-up. Leave open if unused. COMP1 (Pin 4): Comparator Output 1. Real-time logic output with weak 6A pull-up to V2. Pulls high when V1 is above reset threshold. May be pulled greater than V2 using external pull-up. Leave open if unused. V3 (Pin 5): 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 6): 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 0.1F (or greater) capacitor. CRT (Pin 7): 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 25s. A 47nF capacitor generates a 94ms reset delay time. RST (Pin 8): Reset Output. Logic output with weak 6A pull-up to V2. Pulls low when any voltage input is below the reset threshold and held low for the configured delay time after all voltage inputs are above threshold. May be pulled greater than V2 using external pull-up. Leave open if unused. T0 (Pin 9): Supply Tolerance Selection Input. Used in conjunction with T1 (Pin 11). See Applications Information for tolerance selection chart (Table 2). Choose from 5%, 7.5%, 10% or 12.5%. RDIS (Pin 10): Digital Input for RST Disable. A low input on this pin forces RST to V2 (or to the pull-up voltage). Useful for determining supply margins without issuing a reset. A weak internal pull-up allows pin to be left open for normal monitor operation. T1 (Pin 11): Supply Tolerance Selection Input. Used in conjunction with T0 (Pin 9). See Applications Information for tolerance selection chart (Table 2). Choose from 5%, 7.5%, 10% or 12.5%. GND (Pin 12): Ground. VPG (Pin 13): 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 14): 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 15): Voltage Input 4. Select from 1.8V, 1.5V, ADJ or -ADJ. See Applications Information for details. Tie to V1 if unused and configured for positive voltage. V2 (Pin 16): 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 0.1F (or greater) capacitor. All status outputs are weakly pulled up to V2. COMP4 (Pin 17): Comparator Output 4. Real-time logic output with weak 6A pull-up to V2. Pulls high when V4 is above reset threshold. May be pulled greater than V2 using external pull-up. Leave open if unused. COMP2 (Pin 18): Comparator Output 2. Real-time logic output with weak 6A pull-up to V2. Pulls high when V2 is above reset threshold. May be pulled greater than V2 using external pull-up. Leave open if unused.
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LTC2932 PIN FUNCTIONS
V6 (Pin 19): Adjustable Voltage Input 6. High impedance comparator input with 0.5V typical threshold. See Applications Information for details. Tie to V1 if unused. COMP6 (Pin 20): Comparator Output 6. Real-time logic output with weak 6A pull-up to V2. Pulls high when V6 is above reset threshold. May be pulled greater than V2 using external pull-up. Leave open if unused.
BLOCK DIAGRAM
T0 9 T1 11 BUFFER VREF 14 BANDGAP REFERENCE VRTA V2 V2 V2 6A V2 6A A/D 4 V2 6A COMP1 4 COMP2 18 6A COMP3 3 COMP4 17 6A V2 COMP5 1 6A COMP6 20 CMP5 V2 6A RST BUFFER GAIN ADJUST POWER DETECT VCC V1
VPG 13
V1 6 V2 16 V3 5 V4 15 V5 2 RESISTIVE DIVIDER MATRIX 4 V2 CMP1-4 4
VRTA
V6 19 CRT 7
-
VCC
CRT
GND 12
8
+ + - +
CMP6 2A 4
4
-
ADJUSTABLE RESET PULSE GENERATOR
8
22A 10A VCC RDIS 10
2932 BD
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LTC2932 APPLICATIONS INFORMATION
Supply Monitoring The LTC2932 is a low power, high accuracy configurable six supply monitoring circuit with six real-time monitor outputs, a common reset output, a reset disable function and selectable supply thresholds. 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 voltage inputs must be above their predetermined thresholds for the reset not to be activated. The LTC2932 asserts the reset and comparator outputs 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 configured. Once the voltage thresholds are set, if any of the supply monitor inputs is below its configured 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 (10k 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 supervisor 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 specified band; the LTC2932 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 specified tolerance band.
5V SUPPLY TOLERANCE NOMINAL SUPPLY VOLTAGE
MINIMUM RELIABLE SYSTEM VOLTAGE
IDEAL SUPERVISOR THRESHOLD
4.75V 1.5% THRESHOLD BAND 4.675V 4.6V REGION OF POTENTIAL MALFUNCTION
-5% -6.5% -8%
Figure 1. 1.5% Threshold Accuracy Improves System Reliability
The LTC2932 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 between 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 LTC2932's 1.5% specification improves the reliability of the system over supervisors with wider threshold tolerances. Monitor Configuration and Tolerance Selection Select the LTC2932 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 specifies optimum VPG/VREF ratios ( 0.01), when configuring with a ratiometric DAC.
LTC2932 VREF VPG GND R1 1% R2 1%
2932 F02
Figure 2. Mode Selection
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LTC2932 APPLICATIONS INFORMATION
Table 1. Voltage Threshold Modes*
MODE V1 (V) V2 (V) V3 (V) V4 (V) R1 (k) R2 (k) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 5 5 3.3 3.3 3.3 5 5 5 5 5 3.3 3.3 3.3 5 5 5 3.3 3.3 2.5 2.5 2.5 3.3 3.3 3.3 3 3 2.5 2.5 2.5 3.3 3.3 3 ADJ ADJ ADJ ADJ 1.5 2.5 2.5 2.5 2.5 ADJ 1.8 1.8 1.8 1.8 1.8 1.8 ADJ -ADJ ADJ -ADJ ADJ ADJ 1.8 1.5 ADJ ADJ 1.5 ADJ -ADJ -ADJ ADJ ADJ Open 93.1 86.6 78.7 71.5 66.5 59 53.6 47.5 40.2 34.8 28 22.1 16.2 9.53 Short Short 9.53 16.2 22.1 28 34.8 40.2 47.5 53.6 59 66.5 71.5 78.7 86.6 93.1 Open VPG VREF 0.000 0.094 0.156 0.219 0.281 0.344 0.406 0.469 0.531 0.594 0.656 0.719 0.781 0.844 0.906 1
Table 2. Tolerance Selection
T0 Low Low High High T1 Low High Low High TOLERANCE (%) 5 7.5 10 12.5 VREF (V) 1.210 1.178 1.146 1.113
Table 3. Suggested 1% Resistor Values for the ADJ Inputs
VSUPPLY (V) 12 10 8 7.5 6 5 3.3 3 2.5 1.8 1.5 1.2 1 0.9 *See Figure 3. VTRIP (V) 11.25 9.4 7.5 7 5.6 4.725 3.055 2.82 2.325 1.685 1.410 1.120 0.933 0.840 R3 (k) 2150 1780 1400 1300 1020 845 511 464 365 237 182 124 86.6 68.1 R4 (k) 100 100 100 100 100 100 100 100 100 100 100 100 100 100
*V5 and V6 are always adjustable (ADJ).
At power-up, once V1 or V2 reaches 2.4V, the monitor enters a setup period of approximately 150s. During the setup time, the voltage on the VPG pin is sampled and the monitor is configured to the desired input combination. The comparators are enabled and supply monitoring begins. Do not add capacitance to the VPG pin. The two supply tolerance inputs, T0 and T1, configure the global supply tolerance. Larger tolerances provide more headroom by lowering the trip thresholds. Table 2 lists the input combinations for each of the tolerance modes.
VTRIP R3 1% V3, V4, V5 OR V6 R4 1% LTC2932
Table 4. Suggested 1% Resistor Values for the -ADJ Inputs
VSUPPLY (V) -2 -5 -5.2 -10 -12 *See Figure 4. VTRIP (V) -1.87 -4.64 -4.87 -9.31 -11.30 R3 (k) 187 464 487 931 1130 R4 (k) 121 121 121 121 121
VREF R4 1% R3 1% V4
LTC2932
+ -
0.5V 5% TOLERANCE MODE
VTRIP
2932 F03
2932 F04
Figure 3. Setting the Positive Adjustable Trip Point
Figure 4. Setting the Negative Adjustable Trip Point
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LTC2932 APPLICATIONS INFORMATION
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: VTRIP = 0.5V * 1+ R3 R4 Although all six supply monitor comparators have builtin 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 LTC2932 will enter the 150s 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 = 500 [pF / ms] * tRST 2M
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 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 ; V = 1.210V Nominal REF R4
T0, T1 Low (5% Tolerance Mode) Once the resistor divider is set in the 5% tolerance mode, there is no need to change the divider for the other tolerance modes (7.5%, 10%, 12.5%) because VREF is scaled accordingly, moving the trip point in -2.5% increments. 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 = 1.210k 1mA Tables 3 and 4 offer suggested 1% resistor values for various positive and negative supply adjustable applications assuming 5% monitor thresholds.
Leaving the CRT pin unconnected generates a minimum reset timeout of approximately 25s. 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 2A) and capacitor tolerance. A low leakage ceramic capacitor is recommended. Reset Disable Under conventional operation, RST and COMPn will go low when Vn is below its threshold. At any time, the RDIS pin can be pulled low, overriding the reset operation and forcing the RST pin high. This feature is useful when determining supply margins under processor control since the reset command will not be invoked. The RDIS pin is connected to a weak internal pull-up to VCC (10A typical), allowing the pin to be left open if unused.
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11
LTC2932 APPLICATIONS INFORMATION
Six Supply Monitor with Hysteresis The LTC2932 monitors six supply voltages in Figure 5 and is configured to mode 6 (see Table 1). Supply tolerance inputs T0 and T1 are tied to RST. As the LTC2932 powers up, RST is low, which keeps the tolerance at 5%. After all six inputs exceed their 5% threshold voltages, RST pulls high. This changes the supply tolerance to 12.5%. If any of the input voltages drop below the 12.5% threshold level, reset is asserted. The push button on V6 also allows for a manual reset when pressed. Five Supply Power-up Sequencer In Figure 6, the LTC2932's real-time COMP outputs are used to enable DC/DC converters sequentially. The system is powered by a 12V source. The system is started when the push-button is pressed and the LTC2950-1 brings the RUN pin of the LTM4600 high. Subsequently, the LTM4600 generates a 5V output which applies power to each of the 4 DC/DC converters.
5V 0.1F LTC2932 V1 3.3V 2.5V 1.8V 12V 1.2V 124k 1% 2150k 1% V2 V3 V4 V5 V6 VREF R1 59k 1% VPG GND CRT 10k* PUSHBUTTON 100k 1% 100k 1% R2 40.2k 1% COMP1 COMP2 COMP3 COMP4 COMP5 COMP6 RST T0 T1 RDIS CRT 47nF
2932 F05
The LTC2932 is configured to mode 13 and a 12.5% threshold (see Tables 1 and 2). When the threshold is reached on V1, COMP1 pulls high. COMP1 then enables the 3.3V converter first. When the threshold is reached on V2, COMP2 pulls high and enables the 1.8V converter next. When all the converters have been enabled and are good, COMP5 pulls high. RST pulls high 9.4ms after COMP5. Figure 7 shows the power-up sequence of the five supplies and the DONE and RST outputs. If the KILL input on the LTC2950-1 does not receive a logic high from the RST output within 512ms of initial power-up, EN pulls low and the LTM4600 is powered down. In the event that the external 12V supply drops below 9.6V, COMP6 and RST pull low. The LTC2950-1 then receives a logic low on the KILL input, which powers down the LTM4600 and the sequencing circuit.
10k
10k
10k
10k
10k
10k
10k
SYSTEM LOGIC
*OPTIONAL FOR EXTENDED ESD TOLERANCE
tRST = 94ms
Figure 5. Six Supply Monitor with Hysteresis 5% Tolerance (Supplies Rising) 12.5% Tolerance (After RST Goes High)
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LTC2932 APPLICATIONS INFORMATION
12V (9.6V THRESHOLD) LTM4600 VIN VOUT RUN 10k 5V LT3028 VOUT 3.3V SHDN 10k 10k 5V
VIN
3.3V
EN LTC2950-1 VIN INT PB KILL 10k
VIN
LT3028 VOUT 1.8V SHDN
1.8V SYSTEM LOGIC
LTC3704 VOUT -5.2V VIN 10k RUN/UVLO
-5.2V
VIN 10k
LT3028 VOUT 2.5V SHDN
2.5V
DONE 12V SUPPLY STATUS
COMP1 COMP2 COMP3 COMP4 COMP5 COMP6
2932 F06
V1 10k 1820k 1% 0.1F 365k 1% 487k 1% V2 V3 V4 V5 V6 RST 100k 1% 100k 1% 121k 1% VREF R1 16.2k 1% R2 86.6k 1% VPG CRT 4.7nF tRST = 9.4ms GND LTC2932 RDIS T0 T1
Figure 6. Five Supply 12.5% Tolerance Power-Up Sequencer with Pushbutton
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13
LTC2932 APPLICATIONS INFORMATION
PB 5V
3.3V 2.5V 1.8V
-5.2V
DONE
RST
2932 FO7
Figure 7. Five Supply Power-Up Sequencing (Based on Circuit in Figure 6)
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14
LTC2932 PACKAGE DESCRIPTION
F Package 20-Lead Plastic TSSOP (4.4mm)
(Reference LTC DWG # 05-08-1650)
6.40 - 6.60* (.252 - .260) 1.05 0.10 20 19 18 17 16 15 14 13 12 11
6.60 0.10
4.50 0.10
6.40 (.252) BSC
0.45 0.05
0.65 BSC 1 2 3 4 5 6 7 8 9 10 1.10 (.0433) MAX
0 -8
RECOMMENDED SOLDER PAD LAYOUT 4.30 - 4.50** (.169 - .177)
0.25 REF
0.09 - 0.20 (.0035 - .0079)
0.50 - 0.75 (.020 - .030)
0.65 (.0256) BSC
NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS 2. DIMENSIONS ARE IN (INCHES)
0.19 - 0.30 (.0075 - .0118) TYP
0.05 - 0.15 (.002 - .006)
F20 TSSOP 0204
3. DRAWING NOT TO SCALE *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED .152mm (.006") PER SIDE **DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED .254mm (.010") PER SIDE
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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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
15
LTC2932 TYPICAL APPLICATION
Five Supply Adjustable Threshold Monitor with LED Indicators
5V 0.1F LTC2932 V1 3.3V 12V 1.2V 1V 124k 1% 86.6k 1% 2150k 1% V2 V3 V4 V5 V6 VREF COMP1 COMP2 COMP3 COMP4 COMP5 COMP6 RST TO SYSTEM RESET
2932 TA02
1k
1k
1k
1k
1k
CRT VPG GND 100k 1% 100k 1% 100k 1% CRT 47nF T0
RDIS T1 tRST = 94ms
RELATED PARTS
PART NUMBER LTC1326 LTC1728 LTC2900 LTC2901 LTC2902 LTC2903 LTC2904-LTC2907 LTC2908 LTC2909 LTC2910 LTC2912-LTC2914 LTC2915-LTC2918 LTC2928 LTC2930 LTC2931 DESCRIPTION Micropower Triple Supply Monitor for 5V/2.5V, 3.3V and ADJ Micropower Triple Supply Monitor with Open-Drain Reset Programmable Quad Supply Monitor Programmable Quad Supply Monitor Programmable Quad Supply Monitor Precision Quad Supply Monitor Three-State Programmable Precision Dual Supply Monitor Precision Six Supply Monitor (Four Fixed & Two Adjustable) Precision Triple/Dual Input UV, OV and Negative Voltage Monitor Precision Octal Positive/Negative Voltage Supply Monitor Single/Dual/Quad UV and OV Voltage Monitors Single Supply Monitor with 27 Pin-Selectable Thresholds Quad Power Supply Sequencer and Supervisor Configurable Six Supply Monitor with Adjustable Reset Timer, Manual Reset Configurable Six Supply Monitor with Adjustable Reset and Watchdog Timers COMMENTS 4.725V, 3.118V, 1V Threshold (0.75%) and ADJ 5-Lead SOT-23 Package Adjustable Reset, 10-Lead MSOP and DFN Packages Adjustable Reset and Watchdog Timer Adjustable Reset and Tolerance (5%, 7.5%, 10%, or 12.5%) 6-Lead SOT-23 Package 8-Lead SOT-23 and DFN Packages 8-Lead TSOT-23 and DFN Packages Shunt Regulated VCC Pin, Adjustable Threshold and Reset, 8-Lead SOT-23 and DFN Packages 16-Lead SSOP and 5mm x 3mm DFN Packages, H-Grade Temperature Range Separate VCC Pin, Adjustable Reset Timer, H-Grade Temperature Range Manual Reset, Watchdog, TSOT-8/MSOP-10 and 3mm x 2mm DFN Packages, H-Grade Temperature Range Easily Configure Power Management without Software, 36-Lead 5mm x 7mm QFN and SSOP Packages 3mm x 3mm DFN-12 Package, H-Grade Temperature Range TSSOP-20 Package, H-Grade Temperature Range, Individual Supply Comparator Outputs
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16 Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
LT 0408 REV B * PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2008

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