October 2003

3

MIC2044/2045

MIC2044/2045

Micrel

Pin Description

Pin Number

Pin Name

Pin Function

1

PWRGD

Power-Good (Output): Open drain N-Channel device, active high. This pin

asserts high when the voltage at PGREF exceeds its threshold.

2

EN

Switch Enable (Input): Gate control pin of the output MOSFET available as

an active high (–1) or active low (–2) input signal.

3

/FAULT

Fault Status (Output): Open drain N-Channel device, active low. This pin

indicates an overcurrent or thermal shutdown condition. For an overcurrent

event, /FAULT is asserted if the duration of the overcurrent condition lasts

longer than 32ms.

10

GND

Ground connection: Tie to analog ground.

4

SLEW

Slew-Rate Control (Input): A capacitor connected between this pin and

ground will reduce (slow) the output slew-rate. The output turn-on time must

be less than the nominal flag delay of 32ms in order to avoid nuisance

tripping of the /FAULT output since V

200mV of the voltage at the input) before the /FAULT signal delay elapses.

The slew-rate limiting capacitor requires a 16V rating or greater, 25V is

recommended. See

“Applications Information: Output Slew-Rate Adjust-

6

ILIM

Current Limit (Input): A resistor (R

sets the current limit threshold as I

factor specified in the

the continuous output current range is 1A to 6A.

5

UVLOIN

Undervoltage Lockout Adjust (Input): With this pin left open, the UVLO

threshold is internally set to 1.45V. When the switching voltage (V

below 1.5V, connecting an external resistive divider to this input will lower the

UVLO threshold. The total resistance of the divider must be less than 200k

Ω.

To disable the UVLO, tie this pin to VIN. See

further detail.

7,11,13,16

VIN

Switch Supply (Input): Connected to the drain of the output MOSFET. The

range of input for the switch is 0.8V to 5.5V. These pins must be externally

connected together to achieve rated performance.

9,12,14

VOUT

Switch (Output): Connected to the source of the output MOSFET. These

pins must be externally connected together to achieve rated performance.

8

VBIAS

Bias Supply (Input): This input pin supplies power to operate the switch and

internal circuitry. The input range for VBIAS is 1.6V to 5.5V. When switched

voltage (V

desired, connect VBIAS to VIN externally.

15

PGREF

Power-Good Threshold (Input): Analog reference used to specify the

PWRGD threshold. When the voltage at this pin exceeds its threshold, V

PWRGD is asserted high. An external resistive divider network is used to

determine the output voltage level at which V

utilized, this input should be tied to VOUT.