LTC4244CGN#TR Linear Technology, LTC4244CGN#TR Datasheet - Page 11

• Manufacturer Part Number: LTC4244CGN#TR
• Description: IC CTRLR HOT SWAP CPCI 20-SSOP
• Manufacturer: Linear Technology
• Type: Hot-Swap Controllerr

Specifications of LTC4244CGN#TR

• Applications: CompactPCI™
• Internal Switch(s): No
• Voltage - Supply: 3.3V, 5V, ±12V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 20-SSOP (0.154", 3.91mm Width)
• Family Name: LTC4244
• Package Type: SSOP N
• Operating Supply Voltage (min): 2.25/4.25/10/-10.25V
• Operating Supply Voltage (max): 13.5/14.4/-14.4V
• Operating Temperature (min): 0C
• Operating Temperature (max): 70C
• Operating Temperature Classification: Commercial
• Product Depth (mm): 3.99mm
• Product Height (mm): 1.5mm
• Mounting: Surface Mount
• Pin Count: 20
• 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
Hot Circuit Insertion
When a circuit board is inserted into a live CompactPCI
(CPCI) bus, the supply bypass capacitors can draw huge
inrush currents from the CPCI power bus as they charge
up. These transient currents can create glitches on the
power bus, causing other boards in the system to reset.
The LTC4244 is designed to turn a board’s back-end
supply voltages on and off in a controlled manner, allow-
ing the board to be safely inserted or removed from a live
CPCI connector without glitching the system power sup-
plies. It also protects the system supplies from shorts,
precharges the bus I/O connector pins during hot insertion
and extraction, and monitors the supply voltages.
The LTC4244 is specifically designed for CPCI applica-
tions where the Hot Swap controller resides on the plug-
in board.
LTC4244 Feature Summary
• Allows safe insertion and removal from a CPCI back-
• Controls all four CPCI supplies: -12V, 12V, 3.3V and 5V.
• Adjustable foldback current limit for the 5V and 3.3V
• 12V and –12V circuit breakers: if either supply remains
• Adjustable 5V and 3.3V circuit breakers: if either supply
plane.
supplies: an adjustable analog current limit with a 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 analog foldback current limit for more than 25 s, the
circuit breakers will trip, the supplies are turned off and
the FAULT pin is pulled low.
exceeds its current limit for more than 25 s, the circuit
breaker will trip, the supplies will be turned off and the
FAULT pin is asserted low. In the event of a short circuit
on either supply, an analog current limit will prevent the
supply current from exceeding three times the circuit
breaker threshold current.
U
U
W
U
• Current limit during power up: the supplies are allowed
• Internal 12V and –12V power switches.
• PWRGD output: monitors the voltage status of the four
• PCI_RST# combined on chip with HEALTHY# to create
• Precharge output: on-chip reference and error amplifier
• TIMER/AUX. V
• Undervoltage lockout: All four input voltages are pro-
• Space saving 20-pin SSOP package.
LTC4244 vs LTC1644
The LTC4244 is pin-for-pin compatible with the LTC1644.
There are, however, some important differences between
the two parts:
• TIMER: The LTC4244’s TIMER pin threshold voltage is
• V
to power up in current limit. This allows the LTC4244 to
power up boards with widely varying capacitive loads
without tripping the circuit breaker. The maximum
allowable power-up time is adjustable using the TIMER
pin capacitor.
back-end supply voltages.
LOCAL_PCI_RST# output. Simply connect the
PCI_RST# signal to the RESETIN pin and the
LOCAL_PCI_RST# signal to the open-drain RESETOUT
pin.
provide 1V for biasing bus I/O connector pins during
CPCI card insertion and extraction.
pacitor serves as auxiliary V
LTC4244 to ride out large voltage spikes on the 12V
supply without interruption.
tected by undervoltage lockouts.
1.6V below V
up, the LTC4244’s TIMER pin also doubles as auxiliary
V
protecting the V
UVL feature.
CC
EEIN
.
UVL: The LTC4244 has a –9.5V UVL threshold
12VIN
CC
EEIN
: After power-up, the TIMER pin ca-
LTC4244/LTC4244-1
vs 1V for the LTC1644. After power-
supply. The LTC1644 has no V
CC
, thus enabling the
11
42441f
EEIN
IN