MAX5954 Datasheet, PDF (1/22 Pages) Maxim Integrated Products – Single PCI Express, Hot-Plug Controller

19-3914; Rev 1; 1/06
EVAALVUAAILTAIOBNLEKIT
Single PCI Express, Hot-Plug
Controller
General Description
The MAX5954 hot-plug controller is designed for PCI
Express™ applications. The device provides hot-plug
control for 12V, 3.3V, and 3.3V auxiliary supplies of a sin-
gle PCI Express (PCI-E) slot. The MAX5954’s logic
inputs/outputs allow interfacing directly with the system
hot-plug management controller or through an SMBus™
with an external I/O expander. Integrated debounced
attention switch and present-detect signals are included
to simplify system design.
The MAX5954 drives two external n-channel MOSFETs
to control the 12V and 3.3V main outputs. The 3.3V aux-
iliary output is controlled through an internal 0.3Ω
n-channel MOSFET. An internal charge pump provides
gate drive for the 12V output while the gate drive of the
3.3V output is driven by the 12V input supply. The 3.3V
auxiliary output is completely independent from the
main outputs with its own charge pump.
At power-up, the MAX5954 keeps all of the external
MOSFETs off until the supplies rise above their respec-
tive undervoltage-lockout (UVLO) thresholds. The
device keeps the internal MOSFET off only until the aux-
iliary input supply rises above its UVLO threshold. Upon
a turn-on command, the MAX5954 enhances the exter-
nal and internal MOSFETs slowly with a constant gate
current to limit the power-supply inrush current. The
MAX5954 actively limits the current of all outputs at all
times and shuts down if an overcurrent condition per-
sists for longer than a programmable overcurrent time-
out. Thermal-protection circuitry also shuts down all
outputs if the die temperature exceeds +150°C. After an
overcurrent or overtemperature fault condition, the
MAX5954L latches off while the MAX5954A automatical-
ly restarts after a restart time delay. The device is avail-
able in a 36-pin (6mm × 6mm) thin QFN package and
operates over the -40°C to +85°C temperature range.
Applications
Servers
Desktop Mobile Server Platforms
Workstations
Embedded Devices
Typical Application Circuit appears at end of data sheet.
Features
♦ PCI Express Compliant
♦ Hot Swaps 12V, 3.3V, and 3.3V Auxiliary for a
Single PCI-E Slot
♦ Integrated Power MOSFET for Auxiliary Supply
Rail
♦ Controls dI/dt and dV/dt
♦ Active Current Limiting Protects Against
Overcurrent/Short-Circuit Conditions
♦ Programmable Current-Limit Timeout
♦ PWRGD Signal Output with Programmable
Power-On Reset (POR) (160ms Default)
♦ Latched FAULT Signal Output after Overcurrent
or Overtemperature Fault
♦ Attention Switch Input/Output with 4.4ms
Debounce
♦ Present-Detect Input
♦ Forced-On Input Facilitates Testing
♦ Thermal Shutdown
♦ Allows Control through SMBus with an I/O
Expander
Ordering Information
PART
TEMP RANGE
PIN-
PACKAGE
PKG
CODE
MAX5954AETX+ -40°C to +85°C 36 Thin QFN T3666-3
MAX5954LETX+ -40°C to +85°C 36 Thin QFN T3666-3
+Denotes lead free package.
Pin Configuration
TOP VIEW
27 26 25 24 23 22 21 20 19
TIM 28
N.C. 29
N.C. 30
OUTPUT 31
INPUT 32
12VIN 33
MAX5954
GND 34
PGND 35
PORADJ 36
+
1 2345678 9
18 N.C.
17 N.C.
16 N.C.
15 N.C.
14 3.3VAUXIN
13 3.3VAUXO
12 PWRGD
11 FAULT
10 3.3G
SMBus is a trademark of Intel Corp.
PCI Express is a trademark of PCI-SIG Corp.
THIN QFN
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.