LTC2900 View Datasheet(PDF) - Linear Technology

Part Name

Description

Manufacturer

LTC2900

Programmable Quad Supply Monitor with Adjustable Reset Timer

Linear Technology 

LTC2900

PI FU CTIO S

V3 (Pin 1): Voltage Input 3. Select from 2.5V, 1.8V, 1.5V

or ADJ. See Table 1 for details.

V1 (Pin 2): Voltage Input 1. Select from 5V or 3.3V. See

Table 1 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.

CRT (Pin 3): Reset Delay Time Programming Pin. Attach

an external capacitor (CRT) to GND to set a reset delay time

of 4.6ms/nF. Leaving the pin open generates a minimum

delay of approximately 50µs. A 47nF capacitor will gener-

ate a 216ms reset delay time.

RST (Pin 4): Reset Logic Output. Active low with weak

pull-up to V2 (LTC2900-1) or active pull-up to V2

(LTC2900-2). Pulls low when any voltage input is below

the reset threshold and held low for the programmed delay

time after all voltage inputs are above threshold. May be

pulled above V2 using an external pull-up (LTC2900-1

only).

PBR (Pin 5): Manual Reset Pin. Attach a push-button

switch between this pin and ground. A logic low on this pin

will pull RST low. When the PBR pin returns high, RST will

return high after the programmed reset delay assuming all

four voltage inputs are above threshold. A weak internal

pull-up allows the pin to be left floating 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 6): Ground.

VPG (Pin 7): Voltage Threshold Combination Select Input.

Connect to an external 1% resistive divider between 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 8): Buffered Reference Voltage. A 1.210V

nominal reference used for the programming voltage

(VPG) and for the offset of negative adjustable applica-

tions. 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 9): Voltage Input 4. Select from 1.8V, 1.5V, ADJ or

– ADJ. See Table 1 for details.

V2 (Pin 10): 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 the device. Bypass this pin to ground with a 0.1µF (or

greater) capacitor. RST is weakly pulled up to V2

(LTC2900-1). RST is actively pulled up to V2 in the

LTC2900-2.

2900f

7

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