MIC2590B
Micrel
MIC2590B
Dual-Slot PCI Hot Plug Controller
Final Information
General Description
The MIC2590B is a power controller supporting power distri-
bution requirements for Peripheral Component Interconnect
(PCI) hot plug compliant systems incorporating the Intelligent
Platform Management Interface (IPMI). The MIC2590B pro-
vides complete power control support for two PCI slots
including the 3.3V
AUX
defined by the PCI 2.2 specification.
Support for +5V, +3.3V, +12V and –12V supplies is provided
including programmable constant-current inrush limiting,
voltage supervision, programmable current limit, fault report-
ing and circuit breaker functions which provide fault isolation.
The MIC2590B also incorporates a SMBus interface in which
complete status and control of power within each slot is
provided. Data such as voltage and current from each supply
of each slot can be obtained for IPMI sensor records in
addition to power status of each slot.
Features
• Supports two independent PCI 2.2 slots
• SMBus interface for slot power control and status
• +5V, +3.3V, +12V, –12V, +3.3V
AUX
supplies supported
per PCI specification 2.2
• Programmable inrush current-limiting
• Active current regulation controls inrush current
• Electronic circuit breaker
• Dual level fault detection for quick fault response without
nuisance tripping
• Thermal isolation between circuitry for slot A
and slot B
Applications
• PCI hot-plug power distribution
Ordering Information
Part Number
MIC2590B-2BTQ
MIC2590B-5BTQ
5V & 3V Fast-trip
Threshold
100mV
Disabled*
+12V & –12V Fast-trip
Threshold
1.5A/0.4A
1.5A/0.4A
Operating Temp. Range
0°C to +70°C
0°C to +70°C
Package
48-Pin TQFP
48-Pin TQFP
*Contact factory for availability.
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
August 2002
1
MIC2590B
MIC2590B
Micrel
Typical Application
Power
Supply
+12V
—12V
+5.0V
+3.3V
1A Schotty Diode
(Clamp)
VSTBY
12VIN1 12VIN2
VSTBY1
VSTBY2
12SLEWA
12SLEWB
5VGATEA
5VOUTA
C
GATE
CFILTERA
IREF
20k
1%
CFILTERB
3VGATEA
3VOUTA
12VOUTA
12MVOUTA
5VINB
GND
3.3V, 7.6A
12V, 0.5A
—12V, 0.1A
3VINA
3VSENA
C
GATE
R
3VGATEA
R
SENSE
5V, 5A
12MVIN1 12MVIN2
VAUXA
5VINA
5VSENA
R
5VGATEA
R
SENSE
PCI Bus
3.3VAUXA
PCI
Connector
MIC2590B
4.7µF
4.7µF
R
SENSE
PCI Bus
ONA/ONB
AUXENA/AUXENB
/FAULTA, /FAULTB
2
2
2
ONA/ONB
AUXENA/AUXENB
/FAULTA, /FAULTB
A0
5VSENB
5VGATEB
5VOUTB
C
GATE
3VINB
3VSENB
3VGATEB
C
GATE
R
3VGATEB
R
SENSE
R
5VGATEB
5V, 5A
Hot Plug
Controller
A1
A2
/INT
SCL
SDA
3VOUTB
12VOUTB
12MVOUTB
VAUXB
4.7µF
4.7µF
3.3V, 7.6A
12V, 0.5A
—12V, 0.1A
3.3VAUXB
SMBus I/O
SDA
SCL
/INT
SDA
SCL
/INT
Bus Switch
Management
Controller
A
/OE
B
MIC2590B
2
August 2002
MIC2590B
Micrel
Pin Configuration
SDA
SCL
GND
AUXENA
ONA
ONB
AUXENB
A0
A1
A2
GPIB
/INT
/FAULTA
CFILTERA
12VSLEWA
GPIA
12VIN
5VINA
5VSENSEA
5VGATEA
5VOUTA
12VOUTA
VSTBY
3VINA
48 47 46 45 44 43 42 41 40 39 38 37
36
1
2
35
3
34
4
33
5
32
6
31
7
30
8
29
9
28
27
10
26
11
25
12
13 14 15 16 17 18 19 20 21 22 23 24
3VSENSEA
3VGATEA
VAUXA
3VOUTA
12VMIN
12VMIN
12MVOUTA
12MVOUTB
3VOUTB
VAUXB
3VGATEB
3VSENSEB
/FAULTB
CFILTERB
12VSLEWB
IREF
12VIN
5VINB
5VSENSEB
5VGATEB
5VOUTB
12VOUTB
VSTBY
3VINB
48-Pin TQFP (BTQ)
August 2002
3
MIC2590B
MIC2590B
Micrel
Pin Description
Pin Number
6, 31
Pin Name
5VINA, 5VINB
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.
12, 25
3VINA, 3VINB
5, 32
12VIN – 2 pins
17,18
12VMIN – 2 pins
10, 27
19, 20
3, 34
45, 42
12VOUTA, 12VOUTB
12MVOUTA, 12MVOUTB
12VSLEWA, 12VSLEWB
AUXENA, AUXENB
16, 21
9, 28
33
7, 30
3VOUTA, 3VOUTB
5VOUTA, 5VOUTB
IREF
5VSENSEA, 5VSENSEB
13, 24
3VSENSEA, 3VSENSEB
MIC2590B
4
August 2002
MIC2590B
Micrel
Pin Description
Pin Number
8, 29
Pin Name
5VGATEA, 5VGATEB
Pin Function
5V Gate Drive Outputs [A/B]: Each connects to the gate of an external N-
Channel MOSFET. During power-up the C
GATE
and the gate of the
MOSFETs are charged by a 20µA 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 this 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.
14, 23
3VGATEA, 3VGATEB
3V Gate Drive Outputs [A/B]: Each connects to the gate of an external N-
Channel MOSFET. During power-up the C
GATE
and the gate of the
MOSFETs are charged by a 20µA 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 this 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.
11, 26
VSTBY – 2 pins
3.3V Standby input voltage required to support PCI 2.2 VAUX input: SMBus,
internal registers and A/D converter run off of VSTBY to ensure chip access
during standby modes. A UVLO circuit prevents turn-on of this supply until
VSTBY rises above its UVLO threshold. Both pins must be tied together at
the chip.
V
AUX
[A/B] output voltages to PCI card slots: These outputs connect the
VAUX pin of the PCI 2.2 Connectors VSTBY via internal 400mΩ MOSFETs
which are current-limited and protected against short circuit faults.
Enable input for MAIN outputs: Rising-edge sensitive. Used to enable or
disable MAIN (5V, 3.3V, +12V, –12V) outputs. Taking ONA/ONB low after a
fault resets the respective slot’s Main Output Fault Latch. Tie these pins to
ground if using SMBus-mode power control.
Open Drain, Active-Low: Asserted whenever the circuit breaker trips due to
a fault condition.
/FAULT[A/B] is reset by bringing the faulted slot’s ON pin low if /FAULT was
asserted in response to a fault condition on one of the slot’s MAIN outputs
(+12V, +5V, +3.3V, or –12V).
/FAULT[A/B] is reset by bringing the faulted slot’s AUXEN pin low if /FAULT
was asserted in response to a fault condition on the slot’s VAUX output.
If a fault condition occurred on both the MAIN and AUX outputs of the same
slot, then both ON and AUXEN must be brought low to de-assert the /FAULT
output.
2, 35
CFILTERA, CFILTERB
Filter Capacitor [A/B]: Capacitors connected between these pins and ground
set the duration of t
FLT
. t
FLT
is the amount of time for which a slot remains in
current-limit before its circuit breaker is tripped.
Interrupt Output: Open Drain, Active-low. Asserted whenever a power fault
is detected. Cleared by writing a logic 1 to the respective active bit into the
Status Register.
15, 22
VAUXA, VAUXB
44, 43
ONA, ONB
1, 36
/FAULTA, /FAULTB
37
/INT
August 2002
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MIC2590B
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