Micrel, Inc.

MIC2582/MIC2583

April 2009

3

M9999-043009-C

Pin Description

Pin Number

8-Pin SOIC

Pin Number

16-Pin QSOP

Pin Name

Pin Name

1

1

/POR

Power-On Reset Output: Open drain N-channel device, Active Low. This pin

requires a pull-up resistor (10k

Ω minimum) to VCC.

2

3

ON

ON Input: Active High. The ON pin, an input to a Schmitt-triggered comparator

used to enable/disable the controller, is compared to a 1.24V reference with

start-up sequence begins when the GATE pin starts ramping up towards its final

the GATE pin is grounded and /FAULT remains high if VCC is above the UVLO

threshold. ON must be low for 20µs in order to initiate a start-up sequence.

Additionally, toggling the ON pin LOW to HIGH resets the circuit breaker.

3

4

CPOR

Power-On Reset Timer: A capacitor connected between this pin and ground sets

begins to charge. When the voltage at CPOR crosses 0.3V, the start-up

20µs.

4

7, 8

GND

Ground Connection: Tie to analog ground.

5

12

FB

Power-Good Threshold Input (Under-voltage Detect): This input is internally

compared to a 1.24V reference with 30mV of hysteresis. An external resistive

divider may be used to set the voltage at this pin. If this input momentarily goes

output under-voltage condition. The /POR signal de-asserts one timing cycle

after the FB pin exceeds the power-good threshold by 30mV. A 5µs filter on this

pin prevents glitches from inadvertently activating this signal.

6

14

GATE

Gate Drive Output: Connects to the gate of an external N-channel MOSFET. An

internal clamp ensures that no more than 9V is applied between the GATE pin

and the source of the external MOSFET. The GATE pin is immediately brought

low when either the circuit breaker trips or an under-voltage lockout condition

occurs.

7

15

SENSE

Circuit Breaker Sense Input: A resistor between this pin and VCC sets the

current limit threshold. Whenever the voltage across the sense resistor exceeds

immediately pulled low. If the voltage across the sense resistor exceeds the fast

power supply faults, then the GATE pin is immediately brought low without delay.

To disable the circuit breaker, the SENSE and VCC pins can be tied together.

availability of other options.

8

16

VCC

Positive Supply Input: 2.3V to 13.2V. The GATE pin is held low by an internal

under-voltage lockout circuit until VCC exceeds a threshold of 2.2V. If VCC

exceeds 13.2V, an internal shunt regulator protects the chip from transient

voltages up to 20V at the VCC and SENSE pins.