LTC4240IGN Linear Technology, LTC4240IGN Datasheet - Page 11

• Manufacturer Part Number: LTC4240IGN
• Description: IC CTRLR HOT SWAP CPCI 28-SSOP
• Manufacturer: Linear Technology
• Type: Hot-Swap Controllerr

Specifications of LTC4240IGN

• Applications: CompactPCI™
• Internal Switch(s): No
• Voltage - Supply: 3.3V, 5V, ±12V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-SSOP (0.150", 3.95mm Width)
• Family Name: LTC4240
• Package Type: SSOP N
• Operating Supply Voltage (min): 2.55/4.45/10.8/-10.5V
• Operating Supply Voltage (max): 5/12/14/-14V
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Product Depth (mm): 3.99mm
• Product Height (mm): 1.5mm
• Mounting: Surface Mount
• Pin Count: 28
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIO S I FOR ATIO
The LTC4240 is a Hot Swap controller that allows a board
to be safely inserted and removed from a CompactPCI bus
slot. The LTC4240 has built-in 2-wire I
interface hardware to allow software control and monitor-
ing of device function and power supply status.
Hot Circuit Insertion
When a circuit board is inserted into a live CompactPCI
(CPCI) backplane slot, supply bypass capacitors on the
board can draw huge supply transient currents from the
CPCI backplane power bus. The transient currents can
cause glitches on the power bus, thus causing other
boards in the system to reset.
The LTC4240 is designed to turn a board’s supply voltages
on and off in a controlled manner, allowing the board to be
safely inserted or removed from a live CPCI slot without
disturbing the system power supplies. The device also
protects the supplies from shorts, precharges the bus I/O
pins during insertion and extraction and monitors the
supply voltages. The LTC4240 includes an I
interface, which allows software control of device func-
tions.
The LTC4240 is specifically designed for CPCI applica-
tions where it resides on the plug-in board. For best
results, a well bypassed backplane is recommended.
LTC4240 Feature Summary
• Allows safe board insertion and removal from a CPCI
• Controls all four CPCI supplies: –12V, 12V, 3.3V and
• Foldback current limit: An analog current limit with a
• 12V and –12V circuit breakers: if either supply remains
backplane. Status LED visually identifies when a board
is ready for removal.
5V.
value that depends on the output voltage. If the output
is shorted to ground, the current limit drops to keep
power dissipation and supply glitches to a minimum.
in current limit for more than 35 s, the circuit breaker
will trip, the supplies will turn off and the FAULT pin
pulls low.
U
U
W
2
2
C compatible
C compatible
U
• Adjustable 5V and 3.3V circuit breakers: if either supply
• I
• Current limit during power-up: the supplies are allowed
• Internal 12V and –12V power switches.
• PWRGD output: indicates the voltage status of the four
• PCI_RST# is combined with HEALTHY# and
• Precharge output: an internal reference and amplifier
• Space saving 28-pin SSOP package.
I
The LTC4240 incorporates an I
and data) interface that allows the user to easily query and
control the status of the LTC4240. A single analog input
pin selects 1 of 32 allowed addresses. The I
2
C Interface
exceeds current limit for more than 35 s, the circuit
breaker will trip, the supplies will be turned off and the
FAULT pin will be pulled low. In addition, an analog loop
will servo the GATE pin to limit the current to three times
circuit breaker limit during transient conditions.
to and read from the device. The user can turn the
device off and on, set the status LED, set RESETOUT
and disable faults on 12V
read the device status: FAULT, RESETIN, RESETOUT
PWRGD, PRSNT1#, PRSNT2#, FAULTCODE0 and
FAULTCODE1. If a fault occurs, the FAULTCODE bits
identify which supply generated the fault.
to power-up in current limit. This allows the LTC4240 to
power-up boards with widely varying capacitive loads
without tripping the circuit breaker. The maximum
allowable power-up time is programmable using an
external capacitor connected to the TIMER pin. See
TIMER section
supply voltages.
with the I
LOCAL_PCI_RST# output. If HEALTHY# asserts,
LOCAL_PCI_RST# is asserted independent of the other
two inputs.
provide 1V for biasing bus I/O connector pins during
CPCI card insertion and extraction.
2
C interface: software control allows user to both write
2
C RESETIN latch output to create
IN
and V
2
C compatible 2-wire (clock
EEIN
. The user can also
LTC4240
2
C bus can be
11
4240f