LTC4241

1

sn4241 4241f

FEATURES

APPLICATIO S

DESCRIPTIO

TYPICAL APPLICATIO

s

Allows Safe Board Insertion and Removal from a

Live PCI Slot

s

Controls 3.3V, 5V, –12V, 12V and 3.3V Auxiliary

Supplies

s

Independent 3.3V Auxiliary Supply Hot Swap

TM

Controller

s

Adjustable Foldback Current Limit with Circuit

Breaker

s

Adjustable Supply Voltage Power-Up Rate

s

High Side Drive for External N-Channel FETs

s

–12V and 12V On-Chip Switches

s

Fault and Power Good Outputs

PCI-Bus with 3.3V Auxiliary

Hot Swap Controller

The LTC

to be safely inserted and removed from a live PCI-bus slot.

It has a primary controller that controls the four PCI

supplies and an independent auxiliary controller to control

the 3.3V auxiliary supply. External N-channel transistors

are used to control the 3.3V, 5V and 3.3V auxiliary supplies

while on-chip switches control the –12V and 12V supplies.

The 3.3V, 5V and 3.3V auxiliary supplies can be ramped up

at an adjustable rate. Electronic circuit breakers protect all

five supplies against overcurrent faults. The foldback

current limit feature reduces current spikes and power

dissipation when shorts occur. The PWRGD output of the

primary controller indicates when all four PCI supplies are

within tolerance. The FAULT output indicates an overcurrent

condition for any of the five supplies.

The LTC4241 is available in the 20-pin narrow SSOP

package.

, LTC and LT are registered trademarks of Linear Technology Corporation.

Hot Swap is a trademark of Linear Technology Corporation.

s

PCI-Based Servers

s

Computer Systems

GND

AUXON

ON

FAULT

PWRGD

C3

10nF

R6

10

Ω

C1

0.047

µF

C2

0.1

µF

R5

10

Ω

R3

0.07

Ω

R2

0.005

Ω

R4

10

Ω

R7

100

Ω

R1

0.007

Ω

LOGIC

RESET

R8 10k

R9 10k

LTC4241

8

1

2

12

5

6

7

20

19

4

11

10

9

13

14

15

3

17

16

18

PCI

POWER

SYSTEM

CONTROLLER

SYSTEM

POWER

SUPPLY

BACKPLANE

CONNECTOR

GND

5V

5A

3.3V

7.6A

500mA

12V

500mA

–12V

100mA

Q1

IRF7413

Q2

IRF7413

Q3

Si2306DS

4241 F01

TIMER

RESET

Figure 1. Hot Swappable PCI and 3.3V Auxiliary Supplies