LTC2930HDD#PBF - LINEAR TECHNOLOGY

LTC2930

2930fa

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

12V

2930 TA01

CRT

47nF

MANUAL RESET

tRST = 94ms

RST

VREF

VPG GND CRT

SYSTEM

LOGIC

121k

16.2k

86.6k

100k

124k

487k

2150k

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

2930fa

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

1V6

VREF

VPG

GND

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)

LTC2930

2930fa

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

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

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

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

RST

tUV

tMRD

TIMING DIAGRAM

LTC2930

2930fa

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)

25 75

2930 G02

–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)

25 75

2930 G04

–25 0 50 100 125

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

TYPICAL TRANSIENT DURATION (μs)

200

250

300

1 10 100

2930 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

2930 G07

225

150

TA = 25°C

RESET OCCURS ABOVE CURVE

V1 (V)

RST OUTPUT VOLTAGE (V)

1234

2930 G08

TA = 25°C

10k PULL-UP FROM RST TO V1

TEMPERATURE (°C)

–50

RESET TIMEOUT PERIOD, tRST (ms)

–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

2930fa

CRT (F)

RESET TIMEOUT PERIOD tRST (s)

2930 G10

100m

10m

100μ

10μ10p 100p 1n 100n 1μ10n

TA = 25°C

V1 OR V2 (V)

ISINK (mA)

2930 G11

01235

TA = 25°C

VOL = 0.4V

VOL = 0.2V

ISINK (mA)

VOL (mV)

300

400

500

2930 G12

200

100

024610

V1 = 5V

V2 = 3V 125°C

85°C

25°C

–40°C

V2 (V)

2.0

PULL-UP CURRENT (μA)

2.5 3.0 3.5 4.0

2930 G13

4.5 5.0

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

2930fa

PIN FUNCTIONS

A/D

BUFFER

1.210V

VPG

VREF

0.5V

2931 BD

BANDGAP

REFERENCE

ADJUSTABLE

RESET PULSE

GENERATOR

POWER

DETECT

VCC

4CRT

6MR

CRT

VCC

22μA

RESISTIVE

DIVIDER

MATRIX

–

GND

6μA

2μA

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

2930fa

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.

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

LTC2930

2930fa

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

LTC2930

2930 F04

VREF

VTRIP

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











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

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:

LTC2930

2930fa

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

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

2930fa

APPLICATIONS INFORMATION

Figure 5. OR-ed System Reset

LTC2930

0.9V

–5.2V

1.8V

3.3V

CRT

47nF

RST

VREF

VPG GND CRT

121k

R1A

16.2k

R2A

86.6k

100k

10k**

10k

100k

487k

86.6k

68.1k

0.1μF

LTC2930

12V

2930 F05

CRT

47nF

MANUAL RESET

PUSHBUTTON

tRST = 94ms

**OPTIONAL FOR EXTENDED ESD TOLERANCE

RST RESET

VREF

VPG GND CRT

100k

R1B

40.2k

R2B

59k

100k

2150k

1400k

1020k

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

2930 F06

365k

487k

tRST = 9.4ms

4.7nF

0.1μF

RST

VPG GNDCRT

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

121k

1500k

100k

16.2k

86.6k

LTC2950-1

VIN INT

PB KILL

10k

LTC2930

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

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

DD Package

12-Lead Plastic DFN (3mm × 3mm)

(Reference LTC DWG # 05-08-1725 Rev A)

LTC2930

2930fa

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

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

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

1.2V

1.5V

3.3V

CRT

47nF

RST

VREF

VPG GND CRT

71.5k

28k

100k

124k

86.6k

68.1k

0.1μF

PUSHBUTTON

RESET

SYSTEM RESET

tRST = 94ms

2930 TA02