MIC2593
Micrel
Pin Description
Pin Number
5
32
Pin Name
12VINA
12VINB
Pin Function
+12V Supply Power [A/B]: Pin 5 is the input to the drain side of the internal
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.
+12V Output [A/B]: Pin 10 is connected to the source terminal of the internal
MOSFET switch for +12V Slot A and pin 27 is connected similarly for Slot B.
–12V Supply Power [A/B]: Pin 17 is the input to the drain side of the internal
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.
–12V Output [A/B]: Pin 19 is connected to the source terminal of the internal
MOSFET switch for –12V Slot A and pin 20 is connected similarly for Slot B.
12V Slew Rate Control [A/B]: Connect capacitors between these pins and
ground to set the output slew rates of the +12V and –12V supplies. See the
“Functional Description” section for more details.
5V Supply Power and Sense Input [A/B]: Pin 6 is the (+) Kelvin-sense
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.
5V Circuit Breaker Sense Input [A/B]: The current limit thresholds are set
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
FLT
(see CFILTER[A/B] pin description), the circuit breaker is tripped and
the GATE pin for the affected supply’s external MOSFET is immediately
pulled low.
5V Power-Good Sense Inputs: Connect to 5V[A/B] outputs. Used to
monitor the 5V output voltages for Power-is-Good status.
5V Gate Drive Output [A/B]: Each pin connects to the gate of an external
N-Channel MOSFET. During power-up, the C
GATE
and the C
GS
of the
MOSFETs are charged by a 25µA 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
FLT
. Whenever an
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.
3.3V Supply Power and Sense Input [A/B]: Pin 12 is the (+) Kelvin-sense
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.
10
27
17
18
12VOUTA
12VOUTB
12MVINA
12MVINB
19
20
3
34
6
31
12MVOUTA
12MVOUTB
12VSLEWA
12VSLEWB
5VINA
5VINB
7
30
5VSENSEA
5VSENSEB
9
28
8
29
5VOUTA
5VOUTB
5VGATEA
5VGATEB
12
25
3VINA
3VINB
M9999-042204
4
April 2004
STMICROELECTRONICS [ STMICROELECTRONICS ]
