MIC2593

Micrel

M9999-042204

4

April 2004

Pin Description

Pin Number

Pin Name

Pin Function

5

12VINA

+12V Supply Power [A/B]: Pin 5 is the input to the drain side of the internal

32

12VINB

MOSFET switch for +12V Slot A. Pin 32 is the input to the drain side of the

internal MOSFET switch for +12V Slot B. These two pins must ultimately

connect to each other within 10 cm of the MIC2593. An undervoltage lockout

circuit (UVLO) prevents the switches from turning on while this input is less

than its lockout threshold.

10

12VOUTA

+12V Output [A/B]: Pin 10 is connected to the source terminal of the internal

27

12VOUTB

MOSFET switch for +12V Slot A and pin 27 is connected similarly for Slot B.

17

12MVINA

–12V Supply Power [A/B]: Pin 17 is the input to the drain side of the internal

18

12MVINB

MOSFET switch for +12V Slot A. Pin 18 is the input to the drain side of the

internal MOSFET switch for –12V Slot B. These two pins must ultimately

connect to each other within 10 cm of the MIC2593. An undervoltage lockout

circuit (UVLO) prevents the switches from turning on while this input is less

than its lockout threshold.

19

12MVOUTA

–12V Output [A/B]: Pin 19 is connected to the source terminal of the internal

20

12MVOUTB

MOSFET switch for –12V Slot A and pin 20 is connected similarly for Slot B.

3

12VSLEWA

12V Slew Rate Control [A/B]: Connect capacitors between these pins and

34

12VSLEWB

ground to set the output slew rates of the +12V and –12V supplies. See the

“Functional Description” section for more details.

6

5VINA

5V Supply Power and Sense Input [A/B]: Pin 6 is the (+) Kelvin-sense

31

5VINB

connection to the supply side of the sense resistor for 5V Slot A. Pin 31 is

the (+) Kelvin sense connection to the supply side of the sense resistor for

5V Slot B. These two pins must ultimately connect to each other within

10 cm of the MIC2593. An undervoltage lockout circuit (UVLO) prevents the

switches from turning on while this input is less than its lockout threshold.

7

5VSENSEA

5V Circuit Breaker Sense Input [A/B]: The current limit thresholds are set

30

5VSENSEB

by connecting sense resistors between these pins and 5VIN[A/B]. When

the current limit threshold of IR = 50mV is reached, the 5VGATE[A/B] pin

is modulated to maintain a constant voltage across the sense resistor and

therefore a constant current into the load. If the 50mV threshold is exceeded

for t

the GATE pin for the affected supply’s external MOSFET is immediately

pulled low.

9

5VOUTA

5V Power-Good Sense Inputs: Connect to 5V[A/B] outputs. Used to

28

5VOUTB

monitor the 5V output voltages for Power-is-Good status.

8

5VGATEA

5V Gate Drive Output [A/B]: Each pin connects to the gate of an external

29

5VGATEB

N-Channel MOSFET. During power-up, the C

MOSFETs are charged by a 25

µA current source. This controls the value of

dv/dt seen at the source of the MOSFETs, and hence the current flowing into

the load capacitance.

During current-limit events, the voltage at the pin is adjusted to maintain

constant current through the switch for a period of t

overcurrent, thermal shutdown, or input undervoltage fault condition occurs,

the GATE pin for the affected slot is immediately brought low.

During power-down, these pins are discharged by an internal current source.

12

3VINA

3.3V Supply Power and Sense Input [A/B]: Pin 12 is the (+) Kelvin-sense

25

3VINB

connection to the supply side of the sense resistor for 3.3V Slot A. Pin 25 is

the (+) Kelvin-sense connection to the supply side of the sense resistor for

3.3V Slot B. These two pins must ultimately connect to each other within 10

cm of the MIC2593. An undervoltage lockout circuit (UVLO) prevents the

switches from turning on while this input is less than its lockout threshold.