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LTC2902

Programmable Quad Supply Monitor with Adjustable Reset Timer and Supply Tolerance

Linear Technology 

LTC2902

PI FU CTIO S

RST (Pin 6): Reset Logic Output. Active low with weak

pull-up to V2 (LTC2902-1) or active pull-up to V2

(LTC2902-2). Pulls low when any voltage input is below

the reset threshold and held low for programmed delay

time after all voltage inputs are above threshold. May be

pulled above V2 using an external pull-up (LTC2902-1

only).

T0 (Pin 7): Digital Input for Supply Tolerance Selection

(5%, 7.5%, 10% or 12.5%). Used in conjunction with T1

(Pin 9). See Applications Information for tolerance selec-

tion chart (Table 4).

RDIS (Pin 8): Digital Input for RST Disable. A low input on

this pin forces the RST output to V2 (or pull-up voltage).

Useful for determining supply margins without issuing

reset command to processor. A weak internal pull-up

allows pin to be left floating for normal monitor operation.

T1 (Pin 9): Digital Input for Supply Tolerance Selection

(5%, 7.5%, 10% or 12.5%). Used in conjunction with T0

(Pin 7). See Applications Information for tolerance selec-

tion chart (Table 4).

GND (Pin 10): Ground.

VPG (Pin 11): Voltage Threshold Combination Select

Input. Connect to an external 1% resistive divider be-

tween VREF and GND to select 1 of 16 combinations of

preset and/or ±adjustable voltage thresholds (see Table␣ 1).

Do not add capacitance on the VPG pin.

VREF (Pin 12): Buffered Reference Voltage. A 1.210V

nominal reference used for programming 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 13): Voltage Input 4. Select from 1.8V, 1.5V, ADJ

or – ADJ. See Table 1 for details.

V2 (Pin 14): Voltage Input 2. Select from 3.3V, 3V or 2.5V.

See Table 1 for details. The greater of (V1, V2) is also VCC

for chip. Bypass this pin to ground with a 0.1µF (or greater)

capacitor. All logic outputs (COMP1, COMP2, COMP3,

COMP4) are weakly pulled up to V2. RST is weakly pulled

up to V2 in the LTC2902-1 and RST is actively pulled up to

V2 in the LTC2902-2.

COMP4 (Pin 15): Comparator Output 4. Nondelayed,

active high logic output with weak pull-up to V2. Pulls high

when V4 is above reset threshold. May be pulled greater

than V2 using external pull-up.

COMP2 (Pin 16): Comparator Output 2. Nondelayed,

active high logic output with weak pull-up to V2. Pulls high

when V2 is above reset threshold. May be pulled greater

than V2 using external pull-up.

2902f

8

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