MIC2590B-2YTQ Micrel Inc, MIC2590B-2YTQ Datasheet - Page 12

• Manufacturer Part Number: MIC2590B-2YTQ
• Description: IC PCI HOT PLUG CTLR DUAL 48TQFP
• Manufacturer: Micrel Inc
• Type: Hot-Swap Controllerr

Specifications of MIC2590B-2YTQ

• Applications: PCI, PCI-X
• Internal Switch(s): No
• Voltage - Supply: 3.3V, 5V, ±12V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 48-TQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 576-2201; MIC2590B-2YTQ

equation above computes the minimum value to
guarantee the device does not enter into current limit. The
slew rate dv/dt is computed by:
By appropriate selection of the value of C
ensured that the magnitude of the inrush current never
exceeds the current limit for a given load capacitance.
Since one capacitor fixes the slew rate for both +12V and
–12V, the capacitor value should be chosen to provide the
slower slew rate of the two. Table 2 depicts the output
slew rate for various values of C
Power Down Cycle
When a slot is turned off, internal switches are connected
to each of the outputs to discharge the PCI board's
bypass capacitors to ground.
Standby Mode
Standby mode is entered when any one (or more)
enabled MAIN supply input(s) (12V
3V
MIC2590B supplies two 3.3V auxiliary outputs, V
satisfying PCI 2.2 specifications. These outputs are fed
via the V
inputs or via their SMI bus Control Registers. These
outputs are independent of the MAIN outputs: should one
or more of the MAIN supply inputs move below its UVLO
thresholds, V
present. Prior to entering standby mode, ONA and ONB
(or the MAINA and MAINB bits in the Control Registers)
inputs should be de-asserted. If this is not done, the
MIC2590B will assert /FAULT, and also /INT if interrupts
are
undervoltage condition on a supply input.
Circuit Breaker Functions
The MIC2590B provides an electronic circuit breaker
function that protects against excessive loads such as
short circuits at each supply. When the current from one
or more of a slot’s MAIN outputs exceeds the current limit
threshold (50mV/R
and/or 0.2Afor –12V) for a duration greater than t
circuit breaker is tripped and all MAIN supplies (all outputs
except V
exceed I
Micrel, Inc.
September 2008
IN
) drops below its respective UVLO threshold. The
enabled,
dv/dt
Table 2. ±12V Output Slew Rate Selection
AUX
THFAST
STBY
0.001µF
0.01µF
C
0.1µF
1µF
[A/B]) are shut off. Should the load current
GATE
AUX
at
input, and controlled by the AUXEN[A/B]
load
[A/B] still function as long as V
(+12V and –12V), or cause a MAIN
when
SENSE
=
I
SLEW
C
for 3.3V and 5V, 1.0A for +12V,
SLEW
the
I
SLEW
= 25µA
×
MIC2590B
SLEW
10
6
.
IN
, 12MV
dv/dt (load)
22000V/s
2200V/s
220V/s
22V/s
SLEW
detects
IN
, 5V
, it can be
AUX
FLT
STBY
IN
[A/B],
, the
and
an
is
12
output’s V
outputs are shut off with no delay. Undervoltage
conditions on the MAIN supply inputs also trip the circuit
breaker, but only when the MAIN outputs are enabled (to
signal a supply input brown-out condition).
The V
breaker functions. V
threshold, but instead regulate the output current into a
fault to avoid exceeding their operating current limit. The
circuit breaker will trip due to overcurrents on V
when the fault timer expires. This use of the t
prevents the circuit breaker from tripping prematurely due
to brief current transients.
Following a fault condition, the outputs can be turned on
again via the ON inputs (if the fault occurred on one of the
MAIN outputs), via the AUXEN inputs (if the fault occurred
on the AUX outputs), or by cycling both ON and AUXEN
(if faults occurred on both the MAIN and AUX outputs). A
fault condition can alternatively be cleared under SMI
control of the ENABLE bits in the C
When the circuit breaker trips, /FAULT[A/B] will be
asserted if the outputs were enabled through the hot plug
Interface (non-SMI mode) inputs. At the same time, /INT
will be asserted (unless interrupts are masked). Note that
/INT is de-asserted by writing a logic 1 back into the
respective fault bit position(s) in the STAT[A/B] register or
the Common Status Register.
t
the C
determine the capacitor value for a given duration of t
Thermal Shutdown
The internal +12V, –12V and VAUX MOSFETs are
protected against damage not only by current limiting, but
by dual-mode over-temperature protection as well. Each
slot controller on the MIC2590B is thermally isolated from
the other. Should an overcurrent condition raise the
junction temperature of one slot’s controller and internal
pass elements to 140°C, all of the outputs for that slot
(including V
output will be asserted. The other slot’s operation will
remain unaffected. However, should the MIC2590B’s
overall die temperature exceed 160°C, both slots (all
outputs, including V
whether or not a current-limit condition exists. A 160°C
overtemperature
overtemperature bit (OT_INT) in the Common Status
Register.
A/D Converter
The MIC2590B has a 20-channel, 8-bit A/D converter
capable of monitoring the output voltage and current of
each supply. This information is available via the System
Management Interface. The information is particularly
FLT
is set by external capacitors, C
FILTER
AUX
C
[A/B] outputs have their own separate circuit
SENSE
FIL
[A/B] pins. The equation below can be used to
AUX
≅
) will be shut off, and the slot’s /FAULT
2.0μ.
to exceed V
condition
AUX
AUXA
×
[A/B] do not incorporate a fast-trip
⎛
⎜ ⎜
⎝
1second
and V
t
FLT
THFAST
additionally
AUXB
⎞
⎟ ⎟
⎠
(+3.3V and +5V), the
FIL
) will be shut off,
[A/B], connected to
NTRL
[A/B] registers.
M9999-091808
MIC2590B
sets
AUX
FLT
timer
[A/B]
FLT
the
: