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LTC2932I

Confi gurable Six Supply Monitor with Adjustable Reset Timer and Supply Tolerance

Linear Technology 

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.

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.

5V

3.3V

2.5V

1.8V

12V

2150k 1%

1.2V 124k 1%

0.1μF

R1

59k

1%

PUSHBUTTON

10k*

100k 100k

1% 1%

R2

40.2k

1%

*OPTIONAL FOR EXTENDED ESD TOLERANCE

LTC2932

V1

COMP1

V2

COMP2

V3

COMP3

V4

COMP4

V5

COMP5

V6

COMP6

VREF

VPG

GND CRT

RST

T0

T1

RDIS

CRT

47nF

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

SYSTEM

LOGIC

2932 F05

tRST = 94ms

Figure 5. Six Supply Monitor with Hysteresis

5% Tolerance (Supplies Rising)

12.5% Tolerance (After RST Goes High)

2932fb

12

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