General Description
The MAX5946 dual hot-plug controller is designed for
PCI ExpressTM applications. The device provides hot-
plug control for 12V, 3.3V, and 3.3V auxiliary supplies of
two PCI express slots. The MAX5946's logic inputs/out-
puts allow interfacing directly with the system hot-plug
management controller or through an SMBusTM with an
external I/O expander. An integrated debounced atten-
tion 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 aux-
iliary outputs are controlled through internal 0.3
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 respec-
tive 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 +150C. After an
overcurrent or overtemperature fault condition, the
MAX5946L latches off while the MAX5946A 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 -40C to +85C 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
-40C to +85C
36 Thin QFN
MAX5946LETX
-40C to +85C
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
= +70C)
36-Pin Thin QFN (derate 26.3mW/C above +70C).....2.105W
Operating Temperature Range ...........................-40C to +85C
Junction Temperature ......................................................+150C
Storage Temperature Range .............................-65C to +150C
Lead Temperature (soldering, 10s) .................................+300C
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
= -40C to +85C, unless otherwise noted.
Typical values are at T
A
= +25C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
12V SUPPLY
12V Supply Voltage Range
V
12VIN
10.8
12
13.2
V
V
12VIN
rising
9.5
10
10.5
12VIN Undervoltage Lockout
V
12UVLO
Hysteresis
0.1
V
12VIN Supply Current
I
12VIN
V
12VIN
= 13.2V
0.5
1
mA
12VIN CONTROL
12VIN Current-Limit
Threshold (V
12S_+
- V
12S_-
)
V
12ILIM
49
54
59
mV
12G_ Gate Charge Current
I
12G_CHG
V
12G_
= GND
4
5
6
A
Normal turn-off, ON_ = GND, V
12G
_ = 2V
50
150
250
A
12G_ Gate Discharge Current
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
50
120
180
mA
12G_ Gate High Voltage
(V
12G_
- V
12VIN
)
V
12G_H
I
12G_
= 1A
4.8
5.3
5.8
V
12G_ Threshold Voltage For
PWRGD_ Assertion (Note 2)
V
PGTH12
Referred to V
12VIN
, I
12G_
= 1A
-3.0
-4
-4.8
V
12S_- Input Bias Current
1
A
12S_+ Input Bias Current
20
60
A
3.3V SUPPLY
3.3V Supply Voltage Range
V
3.3SA+
,
V
3.3SB+
3.0
3.3
3.6
V
3.3SA+ rising
2.52
2.65
2.78
V
Undervoltage Lockout
(Note 3)
Hysteresis
30
mV
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
= -40C to +85C, unless otherwise noted.
Typical values are at T
A
= +25C.) (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
17
20
23
mV
3.3G_ Gate Charge Current
I
3.3G_CHG
V
3.3G_
= GND
4
5
6
A
ON_ = GND, V
3.3G_
= 2V
50
150
250
A
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
100
150
220
mA
3.3G_ Gate High Voltage
(V
3.3G_
- V
3.3S_+
)
V
3.3G_H
Sourcing 1A
4.5
5.5
6.8
V
3.3G_ Threshold Voltage For
PWRGD_ Assertion (Note 2)
V
PGTH3.3
Referred to V
3.3VAUXIN
, I
3.3G_
= 1A
-3.0
-4
-4.5
V
3.3S_- Input Bias Current
1
A
3.3S_+ Input Bias Current
20
60
A
3.3V AUXILIARY SUPPLY
3.3VAUXIN Supply Voltage
Range
V
3.3VAUXIN
3.0
3.3
3.6
V
3.3VAUXIN rising
2.52
2.65
2.78
V
3.3VAUXIN Undervoltage
Lockout
V
3 .3 V A U X U V L O
Hysteresis
30
mV
3.3VAUXIN Supply Current
V
3.3VAUXIN
= 3.6V
1.5
3
mA
3.3VAUXIN to 3.3VAUXO_
Maximum Dropout
I
3.3VAUXO_
= 375mA
225
mV
3.3VAUXO_ Current-Limit
Threshold
3.3VAUXO_ shorted to GND
376
470
564
mA
3.3VAUXO_ Threshold For
PWRGD_ Assertion
(V
3.3VAUXIN
- V
3.3VAUXO_
)
(Note 3)
V
PGTH3.3AUX
400
mV
LOGIC SIGNALS
Rising edge
1.0
2.0
V
Input-Logic Threshold
(ON_, FON_, AUXON_,
PRES-DET_, INPUT_)
Hysteresis
25
mV
Input Bias Current
(ON_, AUXON_, INPUT_)
1
A
FON_, PRES-DET_ Internal
Pullup
25
50
75
k
ON_, AUXON_ High-to-Low
Deglitch Time
4
s
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
= -40C to +85C, unless otherwise noted.
Typical values are at T
A
= +25C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
PRES-DET_ High-to-Low
Deglitch Time
t
DEG
3
5
7
ms
PORADJ = open
90
160
250
R
PORADJ
= 20k
35
55
75
R
PORADJ
= 100k
145
265
380
PWRGD_ Power-On Reset
Time (Note 2)
t
POR_HL
R
PORADJ
= 200k
570
ms
PWRGD_ Low-to-High
Deglitch Time
t
POR_LH
4
s
Sinking 2mA
0.1
PWRGD_, FAULT_ Output
Low Voltage
Sinking 30mA
0.7
V
PWRGD_, FAULT_ Output-
High Leakage Current
V
PWRGD_
= V
FAULT_
= 5.5V
1
A
TIM = open
5.5
11
17.0
R
TIM
= 15k
1.4
2.6
3.8
R
TIM
= 120k
12
22
32
FAULT_ Timeout
t
FAULT
R
TIM
= 300k
59
ms
FAULT_ Timeout During
Startup
t
SU
2 x t
FAULT
ms
Autorestart Delay Time
t
RESTART
64 x t
FAULT
ms
Fault Reset Minimum Pulse
Width (Note 4)
t
RESET
100
s
Thermal-Shutdown Threshold
T
SD
T
J
rising
+150
C
Thermal-Shutdown Threshold
Hysteresis
20
C
OUTPUT_ Debounce Time
t
DBC
2.6
4.4
6.2
ms
OUTPUT_ High Voltage
Sourcing 2mA
V
3.3VAUXIN
- 0.3
V
3.3 V AU X IN
V
OUTPUT_ Low Voltage
Sinking 2mA
0.4
V
Note 1: 100% production tested at T
A
= +25C. 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.
MAX5946
Dual PCI Express, Hot-Plug
Controller
_______________________________________________________________________________________
5
12VIN INPUT SUPPLY CURRENT
vs. TEMPERATURE
MAX5946 toc01
TEMPERATURE (C)
SUPPLY CURRENT (mA)
60
35
10
-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)
60
35
10
-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)
60
35
10
-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)
0.5
0.4
0.3
0.2
0.1
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0
0
0.6
12G_ AND 3.3G_ GATE CHARGE
CURRENT vs. TEMPERATURE
MAX5946 toc05
TEMPERATURE (C)
GATE CHARGE CURRENT (
A)
60
35
10
-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 (
A)
60
35
10
-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)
60
35
10
-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)
60
35
10
-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)
60
35
10
-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_ = 10k to 3.3VAUXIN, PWRGDA = 10k to 3.3VAUXO_, T
A
= +25C, unless otherwise noted, see the Typical
Application Circuit.)
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