LTC1643L/LTC1643L-1/LTC1643H
U
U
U
PIN FUNCTIONS
V
EEOUT (Pin 15): –12V Supply Output. A 1.2Ω switch is
12VOUT (Pin 16): 12V Supply Output. A 0.5Ω switch is
connected between 12VIN and 12VOUT. 12VOUT must
exceed11.4VbeforethePWRGDsignalcangohighonthe
LTC1643H and LTC1643L.
connected between VEEIN and VEEOUT. VEEOUT must
exceed –10.8V before the PWRGD signal can go high on
the LTC1643H and LTC1643L.
W
BLOCK DIAGRAM
5V
IN
5V
3V
3V
IN
3V
OUT
3
5V
OUT
14
SENSE
GATE
11
SENSE
13
12
10
9
12V
IN
50µA
–
+
–
+
5V
OUT
3V
OUT
+
–
+
Q8
Q7
–
Q5
200µA
2.5V
UVL
2.5V
UVL
C
C
P3
P4
+
–
ON/ON
FAULT
5
6
Q3
REF
REF
LOGIC
+
–
7
PWRGD
Q4
12V
IN
REF
9.5V
UVL
Q9
Q1
Q2
20µA
C
C
P5
P7
+
–
+
–
Q6
Q10
REF
1643 BD
LTC1643H/LTC1643L
ONLY
LTC1643H/LTC1643L
ONLY
1
16
12V
4
TIMER
2
15
8
GND
12V
IN
V
V
EEOUT
OUT
EEIN
U
W U U
APPLICATIONS INFORMATION
Hot Circuit Insertion
safely inserted or removed from a live PCI slot without
glitching the system power supplies. The chip also pro-
tects the PCI supplies from shorts and monitors the
supply voltages.
When a circuit board is inserted into a live PCI slot, the
supply bypass capacitors on the board can draw huge
transient currents from the PCI power bus as they charge
up. The transient currents can cause permanent damage
totheconnectorpinsandcauseglitchesonthepowerbus,
causing other boards in the system to reset.
The LTC1643H is designed for motherboard applica-
tions, while the LTC1643L/LTC1643L-1 are designed for
CompactPCI applications where the chip resides on the
plug-in board.
TheLTC1643isdesignedtoturnaboard’ssupplyvoltages
on and off in a controlled manner, allowing the board to be
8
Linear [ Linear ]
