MIC2580A-1.6BTS Micrel Inc, MIC2580A-1.6BTS Datasheet - Page 20

• Manufacturer Part Number: MIC2580A-1.6BTS
• Description: IC CTRLR PCI HOT SWAP 24-TSSOP
• Manufacturer: Micrel Inc
• Type: Hot-Swap Controllerr

Specifications of MIC2580A-1.6BTS

• Applications: General Purpose, CompactPCI™
• Internal Switch(s): No
• Voltage - Supply: 3.3V, 5V, ±12V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-TSSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

MIC2580A
CompactPCI™ BD_SEL# Pin Tied to Ground
For applications that use system backplanes with the
BD_SEL# pin tied to ground, the MIC2580A /ON pin is edge
sensitive. Therefore, the /ON pin requires a delay circuit for
proper start-up when the board has already been inserted
into the backplane and the supplies are switched off, then
back on. The circuit, shown in the figure below, allows the
MIC2580A /ON pin to transition from high to low which is
necessary for start-up. The delay time may be increased or
decreased by changing the RC time constant in the circuit,
but the delay time must exceed the ramp time of all system
backplane supplies. The same circuit is functional for hot
swap insertion.
MIC2580A
BD_SEL#
Figure 7. /ON Pin Assertion Delay Circuit
MIC2580A
/RESET
/FAULT
1.2k
/ON
2N3904
2k
2k
50k
10k
3.3µF
1N914
(3.3V or 5V)
On PCB
V
IO
20
PCB Layout Considerations
To achieve accurate current sensing Kelvin connections are
recommended between the supply pin and the respective
sense resistor as shown in Figure 8. PCB trace length should
be kept at a minimum. 0.02 inches per ampere is a minimum
width for 1 oz. copper to prevent damage to traces carrying
high current. Keep these high-current traces as short as
possible.
supply
from
Figure 8. Layout Recommendation
VIN
pin
to
short-length, high-current
(wide) copper traces
SENSE
pin
to
sense resistor
Kelvin
connections
February 2005
Micrel, Inc.
to
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