Datasheet

LTC4350
14
4350fb
compensation capacitor C
P2
can be looked up in Table 1
using t
R
. The value for the zero setting resistor, R
P1
, is
150Ω. This value guarantees the zero is at or above the
crossover frequency.
Table 1
t
R
f
C
= 0.35/t
R
C
P2
5µs 70kHz 0.1µF
10µs 35kHz 0.22µF
20µs 17.5kHz 0.47µF
40µs 8.8kHz 1µF
60µs 5.8kHz 1.5µF
80µs 4.4kHz 2.2µF
100µs 3.5kHz 2.7µF
150µs 2.3kHz 3.3µF
200µs 1.8kHz 4.7µF
300µs 1.2kHz 6.8µF
400µs 0.9kHz 10µF
500µs 0.7kHz 12µF
OTHER APPLICATIONS
The application shown on the first page of this data sheet
assumes that the power supplies and the load reside on
one main board. If the system is a true N + 1 hot swappable
power supply, then the LTC4350 will reside with the power
supply on a daughter card that plugs into the main board.
In this case, the input and output capacitors need to be
hot swapped (see Figure 7). The output capacitors are Hot
Swap protected by the LTC4350. The input capacitors are
Hot Swap protected using the LT
®
4250. Other Hot Swap
parts are described in Table 2.
Table 2
VOLTAGE RANGE PART NUMBER
3.3V to 12V LTC1422 Single Channel
LTC1645 Dual Chanel
3.3V to 15V LTC1642 Overvoltage Protection
2.7V to 16.5V LTC1647 Dual Channel
9V to 80V LT1641 Positive High Voltage
–20V to –80V LT4250 Negative High Voltage
In some cases, the output voltage is below the undervoltage
lockout of the LTC4350. In this case, an external supply
of 3.3V or greater needs to provide for the chip. Figure 8
shows a 1.5V output redundant power supply that uses
24V to 1.5V switching power supplies. The V
CC
pin of
the LTC4350 can be driven from the INTV
CC
pin of the
LTC1629.
applicaTions inForMaTion