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Notice: The information in this document is subject to change without notice

Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset

ASM1834/A/D

rev 1.3

April 2005

Detailed Description

Operation Power Monitor

The ASM1834 supervisors simultaneously detect out-of-

tolerance power supply conditions on both 3.3V and 5V

power supplies. If the voltages at 5VIN or 3.3VIN are outside

the tolerance band, the reset for the falling supply voltage

becomes active. When the monitored supply returns to an in-

tolerance state, the reset remains active for approximately

350ms before returning to the inactive state.

On power-up, the reset signals are kept active for

approximately 350ms after the power supply voltages have

reached the selected tolerance. This allows the power supply

and microprocessor to stabilize before the reset is removed.

All supply current for the ASM1834 devices is drawn from the

Reset Signal Polarity and Output Stage Structure

The ASM1834 and the ASM1834A supervisors have active

LOW reset signals. The ASM1834D reset outputs are active

HIGH.

The ASM1834 and the ASM1834D have CMOS push-pull

output stages. The ASM1834A has open drain reset outputs.

Part #

RESET

Polarity

Output Stage

Configuration

ASM1834

LOW

Push-Pull

ASM1834U

LOW

Push-Pull

ASM1834S

LOW

Push-Pull

ASM1834A

LOW

Open Drain

ASM1834AU

LOW

Open Drain

ASM1834AS

LOW

Open Drain

ASM1834D

HIGH

Push-Pull

ASM1834DU

HIGH

Push-Pull

ASM1834DS

HIGH

Push-Pull

RESET

RESET

Figure 1: Timing Diagram: Power Up (ASM1834D only)

RESET

RESET

Figure 2: Timing Diagram: Power Down (ASM1834D only)

RESET Slews