MAXIM MAX5946 Technical data
General Description
The MAX5946 dual hot-plug controller is designed for
PCI Express™ applications. The device provides hotplug control for 12V, 3.3V, and 3.3V auxiliary supplies of
two PCI express slots. The MAX5946’s logic inputs/outputs allow interfacing directly with the system hot-plug
management controller or through an SMBus™ with an
external I/O expander. An integrated debounced attention switch and present-detect signals are included to
simplify system design.
The MAX5946 drives four external n-channel MOSFETs
to control the 12V and 3.3V main outputs. The 3.3V auxiliary outputs are controlled through internal 0.3Ω
n-channel MOSFETs. Internal charge pumps provide
gate drive for the 12V outputs while the gate drive of
the 3.3V output is driven by the 12V input supply. The
3.3V auxiliary outputs are completely independent from
the main outputs with their own charge pumps.
At power-up, the MAX5946 keeps all of the external
MOSFETs off until the supplies rise above their respective undervoltage lockout (UVLO) thresholds. The
device keeps the internal MOSFETs off only until the
auxiliary input supply rises above its UVLO threshold.
Upon a turn-on command, the MAX5946 enhances the
external and internal MOSFETs slowly with a constant
gate current to limit the power-supply inrush current.
The MAX5946 actively limits the current of all outputs at
all times and shuts down if an overcurrent condition
persists for longer than a programmable overcurrent
timeout. Thermal-protection circuitry also shuts down all
outputs if the die temperature exceeds +150°C. After an
overcurrent or overtemperature fault condition, the
MAX5946L latches off while the MAX5946A automatically restarts after a restart time delay. The device is available 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
Features
♦ PCI Express Compliant
♦ Hot Swaps 12V, 3.3V, and 3.3V Auxiliary for 2
PCI-E Slots
♦ Integrated Power MOSFET for Auxiliary Supply
Rails
♦ Controls dI/dt and dV/dt
♦ Active Current Limiting Protects Against
Overcurrent/Short-Circuit Conditions
♦ Programmable Current-Limit Timeout
♦ PWRGD Signal Outputs with Programmable
Power-On Reset (POR) (160ms Default)
♦ Latched FAULT Signal Output after Overcurrent
or Overtemperature Fault
♦ Attention Switch Inputs/Outputs with 4ms
Debounce
♦ Present-Detect Inputs
♦ Forced-On Inputs Facilitates Testing
♦ Thermal Shutdown
♦ Allows Control through SMBus with an I/O
Expander
MAX5946
Dual PCI Express, Hot-Plug
Controller
________________________________________________________________ Maxim Integrated Products 1
19-3483; Rev 0; 11/04
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.
EVALUATION KIT
AVAILABLE
ONB
AUXONB
12SB+
12GB
3.3SB+
3.3SB-
PRES-DETB
1
2
3
4
5
6
7
8
9
27
26
25
24
23
22
21
20
19
3.3VAUXIN
3.3VAUXOB
PWRGDB
3.3GB
3.3VAUXOA
PWRGDA
FAULTA
3.3GA
PGND
GND
12VIN
INPUT1
OUTPUT1
OUTPUT2
INPUT2
TIM
PORADJ
THIN QFN
MAX5946
TOP VIEW
12SB-
FAULTB
FONB
ONA
AUXONA
12SA+
12GA
3.3SA+
3.3SA-
PRES-DETA
12SA-
FONA
36 35 34 33 32 31
30 29 28
10 11 12
13 14 15 16 17 18
Pin Configuration
Ordering Information
PART TEMP RANGE PIN-PACKAGE
MAX5946AETX
-40°C to +85°C 36 Thin QFN
MAX5946LETX
-40°C to +85°C 36 Thin QFN
Typical Application Circuit appears at end of data sheet.
SMBus is a trademark of Intel Corp.
PCI Express is a trademark of PCI-SIG Corp.
MAX5946
Dual PCI Express, Hot-Plug
Controller
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
(All voltages referenced to GND, unless otherwise noted.)
12VIN......................................................................-0.3V to +14V
12GA, 12GB ..............................................-0.3V to (V
12VIN
+ 6V)
12SA+, 12SA-, 12SB+, 12SB-,
3.3GA, 3.3GB .....................................-0.3V to (V
12VIN
+ 0.3V)
3.3VAUXIN, ONA, ONB,
FAULTA, FAULTB ............-0.3V to +6V
PWRGDA, PWRGDB ................................................-0.3V to +6V
PGND ....................................................................-0.3V to +0.3V
All Other Pins to GND......................-0.3V to (V
3.3VAUXIN
+ 0.3V)
Continuous Power Dissipation (T
A
= +70°C)
36-Pin Thin QFN (derate 26.3mW/°C above +70°C).....2.105W
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
ELECTRICAL CHARACTERISTICS
(V
12VIN
= V
12S_-
= V
12S_+
= 12V, V
3.3S_+
= V
3.3S_-
= V
3.3VAUXIN
= V
ON_
= V
AUXON_
= V
FON__
= 3.3V, PWRGD_ = FAULT_ = PORADJ
= TIM = OUTPUT_ = 12G_ = 3.3G_ = OPEN, INPUT_ = PRES_DET_ = PGND = GND, T
A
= -40°C to +85°C, unless otherwise noted.
Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
CONDITIONS
UNITS
12V SUPPLY
12V Supply Voltage Range V
12VIN
V
V
12UVLO
Hysteresis
V
12VIN Supply Current I
12VIN
V
12VIN
= 13.2V
1mA
12VIN CONTROL
12VIN Current-Limit
Threshold (V
12S_+
- V
12S_-
)
V
12ILIM
mV
12G_ Gate Charge Current
V
12G_
= GND 4 5 6 µA
Normal turn-off, ON_ = GND, V
12G
_ = 2V
µA
I
12G_DIS
O utp ut shor t- ci r cui t cond i ti on, str ong g ate p ul l d ow n
to r eg ul ati on, V
1 2V IN
- V
1 2S _
≥ 1V , V
1 2G_
= 5V
mA
12G_ Gate High Voltage
(V
12G_
- V
12VIN
)
V
12G_H
I
12G_
= 1µA
V
12G_ Threshold Voltage For
PWRGD_ Assertion (Note 2)
V
PGTH12
Referred to V
12VIN
, I
12G_
= 1µA
-4
V
12S_- Input Bias Current 1µA
12S_+ Input Bias Current
µA
3.3V SUPPLY
3.3V Supply Voltage Range
V
3.3SA+
,
V
3.3SB+
V
3.3SA+ rising
V
Undervoltage Lockout
(Note 3)
Hysteresis
mV
12VIN Undervoltage Lockout
SYMBOL
V
12VIN
rising
MIN TYP MAX
10.8 12 13.2
9.5 10 10.5
0.1
0.5
49 54 59
I
12G_CHG
12G_ Gate Discharge Current
50 150 250
50 120 180
4.8 5.3 5.8
-3.0
-4.8
2.52 2.65 2.78
20 60
3.0 3.3 3.6
30
MAX5946
Dual PCI Express, Hot-Plug
Controller
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
12VIN
= V
12S_-
= V
12S_+
= 12V, V
3.3S_+
= V
3.3S_-
= V
3.3VAUXIN
= V
ON_
= V
AUXON_
= V
FON__
= 3.3V, PWRGD_ = FAULT_ = PORADJ
= TIM = OUTPUT_ = 12G_ = 3.3G_ = OPEN, INPUT_ = PRES_DET_ = PGND = GND, T
A
= -40°C to +85°C, unless otherwise noted.
Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
3.3V CONTROL
3.3V Current-Limit Threshold
(V
3.3S_+
- V
3.3S_-
)
V
3.3ILIM
mV
3.3G_ Gate Charge Current
V
3.3G_
= GND 4 5 6 µA
ON_ = GND, V
3.3G_
= 2V
µA
3.3G_ Gate Discharge
Current
I
3.3G_DIS
O utp ut shor t- ci r cui t cond i ti on, str ong g ate p ul l d ow n
to r eg ul ati on, V
3 .3 S _ +
- V
3 .3 S _
≥ 1V , V
3 .3 G_
= 5V
mA
3.3G_ Gate High Voltage
(V
3.3G_
- V
3.3S_+
)
V
3.3G_H
Sourcing 1µA
V
3.3G_ Threshold Voltage For
PWRGD_ Assertion (Note 2)
V
PGTH3.3
Referred to V
3.3VAUXIN
, I
3.3G_
= 1µA
-4
V
3.3S_- Input Bias Current 1µA
3.3S_+ Input Bias Current
µA
3.3V AUXILIARY SUPPLY
3.3VAUXIN Supply Voltage
Range
V
3.3VAUXIN rising
V
3.3VAUXIN Undervoltage
Lockout
Hysteresis
mV
3.3VAUXIN Supply Current V
3.3VAUXIN
= 3.6V
3mA
3.3VAUXIN to 3.3VAUXO_
Maximum Dropout
I
3.3VAUXO_
= 375mA
mV
3.3VAUXO_ Current-Limit
Threshold
3.3VAUXO_ shorted to GND
mA
3.3VAUXO_ Threshold For
PWRGD_ Assertion
(V
3.3VAUXIN
- V
3.3VAUXO_
)
(Note 3)
mV
LOGIC SIGNALS
Rising edge
V
Input-Logic Threshold
(ON_, FON_, AUXON_,
PRES-DET_, INPUT_)
Hysteresis
mV
Input Bias Current
(ON_, AUXON_, INPUT_)
1µA
FON_, PRES-DET_ Internal
Pullup
kΩ
ON_, AUXON_ High-to-Low
Deglitch Time
4µs
I
3.3G_CHG
V
3.3VAUXIN
V
3 .3 V A U X U V L O
V
PGTH3.3AUX
17 20 23
50 150 250
100 150 220
4.5 5.5 6.8
-3.0
20 60
3.0 3.3 3.6
30
1.5
2.52 2.65 2.78
376 470 564
1.0 2.0
25
-4.5
225
400
25 50 75
MAX5946
Dual PCI Express, Hot-Plug
Controller
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V
12VIN
= V
12S_-
= V
12S_+
= 12V, V
3.3S_+
= V
3.3S_-
= V
3.3VAUXIN
= V
ON_
= V
AUXON_
= V
FON__
= 3.3V, PWRGD_ = FAULT_ = PORADJ
= TIM = OUTPUT_ = 12G_ = 3.3G_ = OPEN, INPUT_ = PRES_DET_ = PGND = GND, T
A
= -40°C to +85°C, unless otherwise noted.
Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
CONDITIONS
UNITS
PRES-DET_ High-to-Low
Deglitch Time
t
DEG
357ms
PORADJ = open
R
PORADJ
= 20kΩ
R
PORADJ
= 100kΩ
PWRGD_ Power-On Reset
Time (Note 2)
t
POR_HL
R
PORADJ
= 200kΩ
ms
PWRGD_ Low-to-High
Deglitch Time
t
POR_LH
4µs
Sinking 2mA
PWRGD_, FAULT_ Output
Low Voltage
Sinking 30mA
V
PWRGD_, FAULT_ OutputHigh Leakage Current
V
PWRGD_
= V
FAULT_
= 5.5V 1 µA
TIM = open
R
TIM
= 15kΩ
R
TIM
= 120kΩ
FAULT_ Timeout t
FAULT
R
TIM
= 300kΩ
ms
FAULT_ Timeout During
Startup
t
SU
2 x t
FAULT
ms
Autorestart Delay Time t
RESTART
ms
Fault Reset Minimum Pulse
Width (Note 4)
t
RESET
µs
T
SD
TJ rising
°C
Thermal-Shutdown Threshold
Hysteresis
°C
OUTPUT_ Debounce Time t
DBC
ms
OUTPUT_ High Voltage Sourcing 2mA
V
3.3VAUXIN
- 0.3
V
OUTPUT_ Low Voltage Sinking 2mA
V
Note 1: 100% production tested at TA= +25°C. Parameters over temperature are guaranteed by design.
Note 2: PWRGD_ asserts a time t
POR_HL
after V
PGTH12
, V
PGTH3.3
, and V
PGTH3.3AUX
conditions are met.
Note 3: The UVLO for the 3.3V supply is sensed at 3.3SA+.
Note 4: This is the time that ON_ or AUXON_ must stay low when resetting a fault condition.
SYMBOL
Thermal-Shutdown Threshold
MIN TYP MAX
90 160 250
35 55 75
145 265 380
570
0.1
0.7
5.5 11 17.0
1.4 2.6 3.8
12 22 32
59
64 x t
FAULT
100
+150
20
2.6 4.4 6.2
V
3.3 V AU X IN
0.4
MAX5946
Dual PCI Express, Hot-Plug
Controller
_______________________________________________________________________________________ 5
12VIN INPUT SUPPLY CURRENT
vs. TEMPERATURE
MAX5946 toc01
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
603510-15
0.491
0.492
0.493
0.494
0.495
0.496
0.497
0.498
0.499
0.500
0.501
0.502
0.503
0.504
0.505
0.490
-40 85
3.3VAUXIN SUPPLY CURRENT
vs. TEMPERATURE
MAX5946 toc02
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
603510-15
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0
-40 85
ON AND AUXON LOW-TO-HIGH THRESHOLD
VOLTAGE vs. TEMPERATURE
MAX5946 toc03
TEMPERATURE (°C)
THRESHOLD VOLTAGE (V)
603510-15
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.0
1.0
-40 85
ON_ OR AUXON_
3.3VAUXO_ OUTPUT VOLTAGE vs. CURRENT
MAX5946 toc04
OUTPUT CURRENT (A)
OUTPUT VOLTAGE (V)
0.50.40.30.20.1
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0
00.6
12G_ AND 3.3G_ GATE CHARGE
CURRENT vs. TEMPERATURE
MAX5946 toc05
TEMPERATURE (°C)
GATE CHARGE CURRENT (µA)
603510-15
4.90
4.95
5.00
5.05
5.10
5.15
5.20
5.25
5.30
5.35
4.85
-40 85
12G_
3.3G_
12G_ AND 3.3G_ GATE DISCHARGE
CURRENT vs. TEMPERATURE
MAX5946 toc06
TEMPERATURE (°C)
GATE DISCHARGE CURRENT (µA)
603510-15
150
155
160
165
170
145
-40 85
3.3G_
12G_
3.3VAUX INTERNAL SWITCH
MAXIMUM DROPOUT vs. TEMPERATURE
MAX5946 toc07
TEMPERATURE (°C)
DROPOUT VOLTAGE (V)
603510-15
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
0
-40 85
AUXILIARY OUTPUT CURRENT = 375mA
12V AND 3.3V CURRENT-LIMIT THRESHOLD
VOLTAGE vs. TEMPERATURE
MAX5946 toc08
TEMPERATURE (°C)
CURRENT-LIMIT THRESHOLD VOLTAGE (mV)
603510-15
10
20
30
40
50
60
0
-40 85
12V CURRENT-SENSE
THRESHOLD
3.3V CURRENT-SENSE
THRESHOLD
AUXILIARY CURRENT LIMIT
vs. TEMPERATURE
MAX5946 toc09
TEMPERATURE (°C)
AUXILIARY CURRENT LIMIT (A)
603510-15
0.455
0.460
0.465
0.470
0.475
0.480
0.485
0.490
0.495
0.500
0.450
-40 85
Typical Operating Characteristics
(V
12VIN
= V
12SA+
= 12V, V
3.3VAUXIN
= V
3.3S_+
= V
ON_
= V
AUXON_
= V
INPUT_
= 3.3V, PRES-DET_ = GND, FON_ = PORADJ = TIM =
float, FAULT_ = 10kΩ to 3.3VAUXIN, PWRGDA = 10kΩ to 3.3VAUXO_, T
A
= +25°C, unless otherwise noted, see the Typical
Application Circuit.)
MAX5946
Dual PCI Express, Hot-Plug
Controller
6 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(V
12VIN
= V
12SA+
= 12V, V
3.3VAUXIN
= V
3.3S_+
= V
ON_
= V
AUXON_
= V
INPUT_
= 3.3V, PRES-DET_ = GND, FON_ = PORADJ = TIM =
float, FAULT_ = 10kΩ to 3.3VAUXIN, PWRGDA = 10kΩ to 3.3VAUXO_, T
A
= +25°C, unless otherwise noted, see the Typical
Application Circuit.)
12VIN UNDERVOLTAGE LOCKOUT
THRESHOLD vs. TEMPERATURE
MAX5946 toc10
TEMPERATURE (°C)
UVLO THRESHOLD (V)
6035-15 10
9.85
9.90
9.95
10.00
10.05
10.10
10.15
10.20
9.80
-40 85
3.3VAUXIN UNDERVOLTAGE LOCKOUT
THRESHOLD vs. TEMPERATURE
MAX5946 toc11
TEMPERATURE (°C)
UVLO THRESHOLD (V)
603510-15
2.62
2.64
2.66
2.68
2.70
2.60
-40 85
12V TURN-ON/OFF TIME
MAX5946 toc12
12G_
20V/div
PWRGD_
5V/div
ON_
5V/div
12V OUTPUT
10V/div
40ms/div
3.3V TURN-ON/OFF TIME
MAX5946 toc13
3.3G_
10V/div
PWRGD_
5V/div
ON_
5V/div
3.3V OUTPUT
5V/div
40ms/div
3.3V AUXILIARY TURN-ON/OFF TIME
MAX5946 toc14
40ms/div
3.3AUXO_
OUTPUT VOLTAGE
2V/div
AUXON_
2V/div
PWRGD
2V/div
12V POWER-UP
MAX5946 toc15
12V OUTPUT
10V/div
PWRGD_
5V/div
12VIN, 12V INPUT
10V/div
12G_
20V/div
40ms/div
MAX5946
Dual PCI Express, Hot-Plug
Controller
_______________________________________________________________________________________ 7
Typical Operating Characteristics (continued)
(V
12VIN
= V
12SA+
= 12V, V
3.3VAUXIN
= V
3.3S_+
= V
ON_
= V
AUXON_
= V
INPUT_
= 3.3V, PRES-DET_ = GND, FON_ = PORADJ = TIM =
float, FAULT_ = 10kΩ to 3.3VAUXIN, PWRGDA = 10kΩ to 3.3VAUXO_, T
A
= +25°C, unless otherwise noted, see the Typical
Application Circuit.)
3.3V INPUT/3.3V AUXILIARY INPUT
POWER-UP
MAX5946 toc16
3.3V OUTPUT
5V/div
PWRGD_
5V/div
3.3VAUXO_
5V/div
3.3G_
10V/div
100ms/div
3.3S_+
5V/div
TURN-ON DELAY 3.3V OUTPUT AND
3.3V AUXILIARY OUTPUT
MAX5946 toc17
4ms/div
5V/div
5V/div
5V/div
5V/div
10V/div
3.3VAUXO_
OUTPUT VOLTAGE
3.3 OUTPUT VOLTAGE
3.3 INPUT,
3.3VAUXIN
3.3G_
PWRGD
FAULT CONDITION ON 12V OUTPUT
(AUTORESTART OPTION MAX5946A)
MAX5946 toc18
12G_
20V/div
FAULT_
5V/div
12V OUTPUT CURRENT
5A/div
100ms/div
12V OUTPUT VOLTAGE
10V/div
t
RESTART
R
LOAD
STEP TO 1.5Ω
FAULT CONDITION ON 3.3V OUTPUT
(AUTORESTART OPTION MAX5946A)
MAX5946 toc19
3.3G_
10V/div
FAULT_
5V/div
3.3V MAIN OUTPUT CURRENT
2A/div
100ms/div
3.3V OUTPUT VOLTAGE
5V/div
t
RESTART
R
LOAD
STEP TO 0.5Ω
FAULT CONDITION ON AUXILIARY OUTPUT
(AUTORESTART OPTION MAX5946A)
MAX5946 toc20
FAULT_
2V/div
3.3VAUXO_ OUTPUT CURRENT
500mA/div
100ms/div
3.3VAUXO_ OUTPUT VOLTAGE
2V/div
t
RESTART
R
LOAD
STEP TO 4Ω
FAULT CONDITION ON 12V OUTPUT
(LATCH OPTION MAX5946L)
MAX5946 toc21
12G_
20V/div
FAULT_
5V/div
12V OUTPUT CURRENT
5A/div
100ms/div
12V OUTPUT VOLTAGE
10V/div
R
LOAD
STEP TO 1.5Ω
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