MIC2590B Datasheet, PDF (4/24 Pages) Micrel Semiconductor – Dual-Slot PCI Hot Plug Controller

MIC2590B
Pin Description
Pin Number
6, 31
12, 25
5, 32
17,18
10, 27
19, 20
3, 34
45, 42
16, 21
9, 28
33
7, 30
13, 24
Pin Name
5VINA, 5VINB
3VINA, 3VINB
12VIN – 2 pins
12VMIN – 2 pins
12VOUTA, 12VOUTB
12MVOUTA, 12MVOUTB
12VSLEWA, 12VSLEWB
AUXENA, AUXENB
3VOUTA, 3VOUTB
5VOUTA, 5VOUTB
IREF
5VSENSEA, 5VSENSEB
3VSENSEA, 3VSENSEB
Micrel
Pin Function
5V Supply Power and Sense Inputs [A/B]: Two pins are provided for Kelvin
connection (one for each slot). 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 10cm. An undervoltage
lockout circuit (UVLO) prevents the switches from turning on while this input is
less than its lockout threshold.
3.3V Supply Power and Sense Inputs [A/B]: Two pins are provided for
Kelvin connection (one for each slot). Pin 12 is the Kelvin sense connection to
the supply side of the sense resistor for 3V Slot A. Pin 25 is the Kelvin sense
connection to the supply side of the sense resistor for 3V Slot B. These two
pins must ultimately connect to each other within 10cm. An undervoltage
lockout circuit (UVLO) prevents the switches from turning on while this input is
less than its lockout threshold.
+12V Supply Input: An undervoltage lockout circuit prevents the switches from
turning on while this input is less than its lockout threshold. Both pins must be
tied together at the chip.
–12V Supply Input: An undervoltage lockout circuit prevents the switches from
turning on while this input is less than its lockout threshold. Both pins must be
tied together at the chip.
12V output [A/B]
–12V output [A/B]
12V Slew Rate Control [A/B]: Connect capacitors between these pins and
ground to set output slew rates of the +12V and -12V supplies.
AUX Enable Inputs [A/B]: Rising-edge sensitive enable inputs for VAUXA
and VAUXB outputs. Taking AUXENA/AUXENB low after a fault resets the
respective slot’s Aux Output Fault Latch. Tie these pins to ground if using
SMBus-mode power control.
3.3V Power-Good Sense Inputs: Connect to 3.3V[A/B] outputs. Used to
monitor the 3.3V output voltages for Power-Good status.
5V Power-Good Sense Inputs: Connect to 5V[A/B] outputs. Used to monitor
the 5V output voltages for Power-Good status.
A resistor connected between this pin and ground sets the ADC current
measurement gain. This resistor must be 20kΩ ±1%.
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, the circuit breaker is tripped and the GATE pin for the affected slot is
immediately pulled low.
3V Circuit Breaker Sense Input [A/B]: The current limit thresholds are set by
connecting sense resistors between these pins and 3VIN[A/B]. When the
current limit threshold of IR = 50mV is reached, the 3VGATE[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, the circuit breaker is tripped and the GATE pin for the affected slot is
immediately pulled low.
MIC2590B
4
August 2002