LTC2932CF#PBF - LINEAR TECHNOLOGY

LTC2932

2932fb

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

Conﬁ gurable Six Supply

Monitor with Adjustable Reset

Timer and Supply Tolerance

The LTC

2932 is a conﬁ gurable supply monitor for sys-

tems 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

conﬁ gurable 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 52μA supply current makes the LTC2932 ideal for

power conscious systems and the part may be conﬁ gured

to monitor less than six inputs.

Six Supply Monitor 12V (ADJ),

5V, 3.3V, 2.5V, 1.8V, 1.2V (ADJ)

■ 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: 52μA

■ Power Supply Glitch Immunity

■ Guaranteed RST for VCC ≥ 1V

■ High Temperature Operation to 125°C

■ 20-Lead TSSOP Package

■ Desktop and Notebook Computers

■ Multivoltage Systems

■ Telecom Equipment

■ Portable Battery-Powered Equipment

■ Network Servers

■ Automotive

COMP1

COMP2

COMP3

COMP4

COMP5

COMP6

LTC2932

1.2V

1.8V

2.5V

3.3V

12V

2932 TA01

tRST = 94ms

CRT

47nF

RST

RDIS

VPG

GND T0 T1 CRT

VREF

SYSTEM

LOGIC

POWER

GOOD

59k

100k

124k

2150k

40.2k

0.1μF

10k

Voltage Threshold Conﬁ guration Table

V1 (V) V2 (V) V3 (V) V4 (V) V5 (V) V6 (V)

5 3.3 2.5 1.8 ADJ ADJ

5 3.3 2.5 1.5 ADJ ADJ

5 3.3 2.5 ADJ ADJ ADJ

5 3.3 1.8 ADJ ADJ ADJ

5 3.3 1.8 –ADJ ADJ ADJ

5 3.3 ADJ ADJ ADJ ADJ

5 3.3 ADJ –ADJ ADJ ADJ

5 3 2.5 ADJ ADJ ADJ

5 3 1.8 ADJ ADJ ADJ

5 3 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

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.

LTC2932

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PIN CONFIGURATIONABSOLUTE MAXIMUM RATINGS

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 ................................................ 0°C to 70°C

LTC2932I..............................................–40°C to 85°C

LTC2932H ..........................................–40°C to 125°C

Storage Temperature Range ...................– 65°C to 150°C

Lead Temperature (Soldering, 10 sec) .................. 300°C

(Notes 1, 2, 3)

F PACKAGE

20-LEAD PLASTIC TSSOP

TOP VIEW

COMP5

COMP3

COMP1

CRT

RST

RDIS

COMP6

COMP2

COMP4

VREF

VPG

GND

TJMAX = 130°C, θJA = 90°C/W

ORDER INFORMATION

LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LTC2932F#PBF LTC2932CF#TRPBF LTC2932F 20-Lead Plastic TSSOP 0°C to 70°C

LTC2932F#PBF LTC2932IF#TRPBF LTC2932F 20-Lead Plastic TSSOP –40°C to 85°C

LTC2932F#PBF LTC2932HF#TRPBF LTC2932F 20-Lead Plastic TSSOP –40°C to 125°C

Consult LTC Marketing for information on non-standard lead based ﬁ nish parts. *Temperature grades are 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, COMPn in Correct Logic State ●1V

VCCMINP Minimum Required for Mode Selection VCC Rising ●2.4 V

VCCMINC Minimum Required for Comparators VCC Falling ●2.3 V

VRT50 5V, 5% Reset Threshold

5V, 7.5% Reset Threshold

5V, 10% Reset Threshold

5V, 12.5% Reset Threshold

V1 Input Threshold ●

●

4.600

4.475

4.350

4.225

4.675

4.550

4.425

4.300

4.750

4.625

4.500

4.375

VRT33 3.3V, 5% Reset Threshold

3.3V, 7.5% Reset Threshold

3.3V, 10% Reset Threshold

3.3V, 12.5% Reset Threshold

V1, V2 Input Threshold ●

●

3.036

2.954

2.871

2.789

3.086

3.003

2.921

2.838

3.135

3.053

2.970

2.888

VRT30 3V, 5% Reset Threshold

3V, 7.5% Reset Threshold

3V, 10% Reset Threshold

3V, 12.5% Reset Threshold

V2 Input Threshold ●

●

2.760

2.685

2.610

2.535

2.805

2.730

2.655

2.580

2.850

2.775

2.700

2.625

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)

LTC2932

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SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

VRT25 2.5V, 5% Reset Threshold

2.5V, 7.5% Reset Threshold

2.5V, 10% Reset Threshold

2.5V, 12.5% Reset Threshold

V2, V3 Input Threshold ●

●

2.300

2.238

2.175

2.113

2.338

2.275

2.213

2.150

2.375

2.313

2.250

2.188

VRT18 1.8V, 5% Reset Threshold

1.8V, 7.5% Reset Threshold

1.8V, 10% Reset Threshold

1.8V, 12.5% Reset Threshold

V3, V4 Input Threshold ●

●

1.656

1.611

1.566

1.521

1.683

1.638

1.593

1.548

1.710

1.665

1.620

1.575

VRT15 1.5V, 5% Reset Threshold

1.5V, 7.5% Reset Threshold

1.5V, 10% Reset Threshold

1.5V, 12.5% Reset Threshold

V3, V4 Input Threshold ●

●

1.380

1.343

1.305

1.268

1.403

1.365

1.328

1.290

1.425

1.388

1.350

1.313

VRTA ADJ, 5% Reset Threshold

ADJ, 7.5% Reset Threshold

ADJ, 10% Reset Threshold

ADJ, 12.5% Reset Threshold

V3, V4, V5, V6 Input Threshold ●

●

492.5

479.4

466.3

453.1

500.0

486.6

473.3

459.9

507.5

494

480.4

466.8

VRTAN –ADJ Reset Threshold V4 Input Threshold ●–18 0 18 mV

VREF Reference Voltage VCC ≥ 2.3V, IVREF = ±1mA, CREF ≤ 1000pF

T0 Low, T1 Low

T0 Low, T1 High

T0 High, T1 Low

T0 High, T1 High

●

1.192

1.160

1.128

1.096

1.210

1.178

1.146

1.113

1.228

1.195

1.163

1.130

VPG Mode Selection Voltage Range VCC ≥ VCCMINP ●0V

REF V

IVPG VPG Input Current VPG = VREF ●±20 nA

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

IV4 V4 Input Current V4 = 1.8V

V4 = 0.55V (ADJ Mode)

V4 = –0.02V (–ADJ Mode)

●

0.34 0.8

±15

μA

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

ICOMPn COMPn Pull-Up Current VCOMPn = GND ●–2 –6 –12 μA

tRST Reset Timeout Period CRT = 1500pF ●234 ms

tUV Vn Undervoltage Detect to RST or

COMPn

Vn Less Than Reset Threshold by More

than 1%

150 μs

VOL Voltage Output Low RST, COMPnISINK = 3mA, VCC = 3V

ISINK = 100μA, VCC = 1V

●

0.15

0.05

0.4

0.3

VOH Voltage Output High RST, COMPn

(Note 5)

ISOURCE = –1μA ●V2-1 V

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)

LTC2932

2932fb

tRST

2932 TD

VRT

RST

COMPn

tUV

Vn Monitor Timing

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 6μA. However, external pull-up resistors 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)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Digital Inputs T0, T1, RDIS

VIL T0, T1 Low Level Input Voltage VCC = 3.3V to 5.5V ●0.3VCC V

VIH T0, T1 High Level Input Voltage VCC = 3.3V to 5.5V ●0.7VCC V

IINTOL T0, T1 Input Current T0, T1 = 2V ●±0.1 ±1 μA

VIL RDIS Input Threshold Low VCC = 3.3V to 5.5V ●0.4 V

VIH RDIS Input Threshold High VCC = 3.3V to 5.5V ●1.6 V

IRDIS RDIS Pull-Up Current VRDIS = 1V ●–4 –10 –16 μA

TIMING DIAGRAM

LTC2932

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TEMPERATURE (°C)

–50

NORMALIZED THRESHOLD VOLTAGES (V/V)

1.005

1.010

1.015

25 75

2932 G01

1.000

0.995

–25 0 50 100 125

0.990

0.985

TEMPERATURE (°C)

–50

THRESHOLD VOLTAGE, VRTAN (mV)

25 75

2932 G02

–6

–25 0 50 100 125

–12

–18

TEMPERATURE (°C)

–50

VREF (V)

1.216

1.222

1.228

25 75

2932 G03

1.210

1.204

–25 0 50 100 125

1.198

1.192

TEMPERATURE (°C)

–50

SUPPLY CURRENT, IV1 (μA)

25 75

2932 G04

–25 0 50 100 125

V1 = 5V

V2 = 3.3V

V3 = 2.5V

V4 = 1.8V

V5 = V6 = 1V

RESET COMPARATOR OVERDRIVE (% OF VRTX)

0.1

TYPICAL TRANSIENT DURATION (μs)

200

250

300

1 10 100

2932 G06

150

100

TA = 25°C

RESET OCCURS ABOVE CURVE

RESET COMPARATOR OVERDRIVE (% OF VRTX)

0.1

TYPICAL TRANSIENT DURATION (μs)

300

375

450

1 10 100

2932 G07

225

150

TA = 25°C

RESET OCCURS ABOVE CURVE

V1 (V)

RST OUTPUT VOLTAGE (V)

1234

2932 G08

TA = 25°C

10k PULL-UP FROM RST TO V1

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

Reset Timeout Period

vs Temperature

TEMPERATURE (°C)

–50

RESET TIMEOUT PERIOD, tRST (ms)

–25 0 25 50

2932 G09

75 100 125

CRT = 1500pF

(SILVER MICA)

V4 (mV)

IV4 (A)

2932 G05

–100μ

–10μ

–1μ

–100n

–10n

–1n

–100p

–300

125°C

90°C

25°C

–250 –200 –50 0–100–150

I(V4) vs V4 in Negative

Adjust Mode

LTC2932

2932fb

V1 OR V2 (V)

ISINK (mA)

2932 G11

01235

TA = 25°C

VOL = 0.4V

VOL = 0.2V

ISINK (mA)

VOL (mV)

300

400

500

2932 G12

200

100

024610

V1 = 5V

V2 = 3V 125°C

85°C

25°C

–40°C

CRT (F)

RESET TIMEOUT PERIOD tRST (s)

2932 G10

100m

10m

100μ

10μ10p 100p 1n 100n 1μ10n

TA = 25°C

TYPICAL PERFORMANCE CHARACTERISTICS

Voltage Output Low vs Output

Sink Current (RST, COMPn)

COMPn Pull-Up Current vs V2 RST Pull-Up Current vs V2

COMPn Propagation Delay vs

Input Overdrive Above Threshold

ISINK vs Supply Voltage

(RST, COMPn)

V2 (V)

PULL-UP CURRENT (μA)

23 45

2932 G13

TA = 25°C

COMPn = GND

INPUT OVERDRIVE ABOVE THRESHOLD (mV)

COMPn PROPAGATION DELAY (μs)

250

200

150

2932 G14

100

1000

10 100

TA = 25°C

V1, V2

V3, V4, V5, V6

V2 (V)

2.0

PULL-UP CURRENT (μA)

2.5 3.0 3.5 4.0

2932 G15

4.5 5.0

TA = 25°C

VRT25

VRT30

VRT33

Reset Timeout Period vs CRT

LTC2932

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PIN FUNCTIONS

COMP5 (Pin 1): Comparator Output 5. Real-time logic

output with weak 6μA 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 6μA 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 6μA 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 0.1μF (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 25μs. A 47nF capacitor generates a 94ms

reset delay time.

RST (Pin 8): 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. 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 Informa-

tion 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 conﬁ gured 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 0.1μF (or greater) capacitor. All status outputs are

weakly pulled up to V2.

COMP4 (Pin 17): Comparator Output 4. Real-time logic

output with weak 6μA 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 6μA 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.

LTC2932

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PIN FUNCTIONS

6μA

COMP6

COMP5

6μA

COMP4

6μA

COMP3

6μA

COMP2

6μA

COMP1

A/D

BUFFER

VRTA

VPG

VREF

VRTA

2932 BD

BANDGAP

REFERENCE

ADJUSTABLE

RESET PULSE

GENERATOR

POWER

DETECT

VCC

CRT

RESISTIVE

DIVIDER

MATRIX

BUFFER GAIN

ADJUST

–

VCC

2μA

10μA

VCC

22μA

CRT

GND

6μA

RST

RDIS

CMP1-4

CMP5

CMP6

BLOCK DIAGRAM

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 6μA 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.

LTC2932

2932fb

APPLICATIONS INFORMATION

Supply Monitoring

The LTC2932 is a low power, high accuracy conﬁ gurable

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 compara-

tor 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 conﬁ gured. Once the 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 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 speciﬁ ed 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 speci-

ﬁ ed tolerance band.

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 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 LTC2932’s ±1.5% speciﬁ cation improves

the reliability of the system over supervisors with wider

threshold tolerances.

Monitor Conﬁ guration 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 speciﬁ es

optimum VPG/VREF ratios (± 0.01), when conﬁ guring with

a ratiometric DAC.

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

2932 F02

VREF

VPG

GND

LTC2932

Figure 2. Mode Selection

LTC2932

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APPLICATIONS INFORMATION

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.

The two supply tolerance inputs, T0 and T1, conﬁ gure 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.

Figure 3. Setting the Positive Adjustable Trip Point

–0.5V

5% TOLERANCE MODE

2932 F03

V3, V4, V5 OR V6

VTRIP

LTC2932

2932 F04

VREF

VTRIP

LTC2932

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 3. 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 4. Suggested 1% Resistor Values for the –ADJ Inputs

T0 T1 TOLERANCE (%) VREF (V)

Low Low 5 1.210

Low High 7.5 1.178

High Low 10 1.146

High High 12.5 1.113

Table 2. Tolerance Selection

Table 1. Voltage Threshold Modes*

MODE V1 (V) V2 (V) V3 (V) V4 (V) R1 (kΩ) R2 (kΩ)

VPG

VREF

0 5 3.3 ADJ ADJ Open Short 0.000

1 5 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 0.281

5 5 3.3 2.5 ADJ 66.5 34.8 0.344

6 5 3.3 2.5 1.8 59 40.2 0.406

7 5 3.3 2.5 1.5 53.6 47.5 0.469

8 5 3 2.5 ADJ 47.5 53.6 0.531

9 5 3 ADJ ADJ 40.2 59 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 71.5 0.719

12 3.3 2.5 1.8 –ADJ 22.1 78.7 0.781

13 5 3.3 1.8 –ADJ 16.2 86.6 0.844

14 5 3.3 1.8 ADJ 9.53 93.1 0.906

15 5 3 1.8 ADJ Short Open 1

*V5 and V6 are always adjustable (ADJ).

LTC2932

2932fb

APPLICATIONS INFORMATION

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 LTC2932 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

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.

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 (10μA typical), allowing

the pin to be left open if unused.

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











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

; VREF = 1.210V Nominal

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 toler-

ance 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

1mA =1.210kΩ

Tables 3 and 4 offer suggested 1% resistor values for vari-

ous positive and negative supply adjustable applications

assuming 5% monitor thresholds.

LTC2932

2932fb

Six Supply Monitor with Hysteresis

The LTC2932 monitors six supply voltages in Figure 5 and

is conﬁ gured 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.

The LTC2932 is conﬁ gured 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 ﬁ rst. 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

ﬁ ve 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.

APPLICATIONS INFORMATION

COMP1

COMP2

COMP3

COMP4

COMP5

COMP6

VREF

VPG

LTC2932

*OPTIONAL FOR EXTENDED ESD TOLERANCE

2932 F05

2150k 1%

59k

40.2k

10k 10k 10k 10k 10k 10k 10k

0.1μF

3.3V

2.5V

1.8V

12V

1.2V

100k

tRST = 94ms

CRT

47nF

RST

GND CRT RDIS

10k*

PUSHBUTTON

124k 1%

SYSTEM

LOGIC

Figure 5. Six Supply Monitor with Hysteresis

5% Tolerance (Supplies Rising)

12.5% Tolerance (After RST Goes High)

LTC2932

2932fb

COMP1 COMP2 COMP3 COMP4 COMP5 COMP6

LTC2932

12V (9.6V THRESHOLD)

12V

SUPPLY

STATUS

DONE

2.5V

–5.2V

1.8V

3.3V

2932 F06

365k

487k

10k 10k

10k 0.1μF

tRST = 9.4ms

4.7nF

RDIS

VPG GND

CRT

RST

VREF

SYSTEM

LOGIC

10k

LT3028

VIN 3.3V

VOUT

SHDN

LTM4600

VIN

VOUT

RUN

10k

LT3028

VIN 1.8V

VOUT

SHDN

10k

LTC3704

VIN –5.2V

VOUT

RUN/UVLO

10k

LT3028

VIN 2.5V

VOUT

SHDN

100k

121k

1820k

100k

16.2k

86.6k

LTC2950-1

VIN INT

PB KILL

APPLICATIONS INFORMATION

Figure 6. Five Supply 12.5% Tolerance Power-Up Sequencer with Pushbutton

LTC2932

2932fb

APPLICATIONS INFORMATION

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)

LTC2932

2932fb

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

F Package

20-Lead Plastic TSSOP (4.4mm)

(Reference LTC DWG # 05-08-1650)

F20 TSSOP 0204

0.09 – 0.20

(.0035 – .0079)

0o – 8o

0.25

REF

0.50 – 0.75

(.020 – .030)

4.30 – 4.50**

(.169 – .177)

134

5678910

111214 13

6.40 – 6.60*

(.252 – .260)

20 19 18 17 16 15

1.10

(.0433)

MAX

0.05 – 0.15

(.002 – .006)

0.65

(.0256)

BSC

6.40

(.252)

BSC

0.19 – 0.30

(.0075 – .0118)

TYP

MILLIMETERS

(INCHES)

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

NOTE:

1. CONTROLLING DIMENSION: MILLIMETERS

2. DIMENSIONS ARE IN

3. DRAWING NOT TO SCALE

RECOMMENDED SOLDER PAD LAYOUT

0.45 p0.05 0.65 BSC

4.50 p0.10

6.60 p0.10

1.05 p0.10

LTC2932

2932fb

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com

LT 0408 REV B • 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

LTC2930 Conﬁ gurable Six Supply Monitor with Adjustable Reset Timer,

Manual Reset

3mm × 3mm DFN-12 Package, H-Grade Temperature Range

LTC2931 Conﬁ gurable Six Supply Monitor with Adjustable Reset and

Watchdog Timers

TSSOP-20 Package, H-Grade Temperature Range,

Individual Supply Comparator Outputs

RELATED PARTS

COMP1

COMP2

COMP3

COMP4

COMP5

COMP6

VREF

CRT

LTC2932

2932 TA02

86.6k 1%

1k 1k 1k 1k 1k

0.1μF

3.3V

12V

1.2V

100k

1% tRST = 94ms

TO SYSTEM RESET

RST

RDIS

GNDVPG T0 T1

2150k 1%

124k 1%

CRT

47nF

Five Supply Adjustable Threshold Monitor with LED Indicators