19-3483; Rev 0; 11/04
KIT
ATION
EVALU
BLE
AVAILA
Dual PCI Express, Hot-Plug
Controller
General Description
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
Applications
Servers
Desktop Mobile Server Platforms
Workstations
Embedded Devices
PRES-DETA
FONA
ONA
AUXONA
12SA+
12SA-
12GA
3.3SA+
3.3SA-
1
2
3
4
5
6
7
8
9
36 35 34 33 32 31 30 29 28
PGND
GND
TOP VIEW
12VIN
INPUT1
OUTPUT1
OUTPUT2
INPUT2
TIM
PORADJ
The MAX5946 dual 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
two PCI express slots. The MAX5946’s logic inputs/out-
puts allow interfacing directly with the system hot-plug
management controller or through an SMBus™ 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 0.3Ω
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 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 +150°C. 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 -40°C to +85°C temperature range.
Ordering Information
PART
MAX5946AETX
MAX5946LETX
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
36 Thin QFN
36 Thin QFN
Pin Configuration
27
26
25
24
PRES-DETB
FONB
ONB
AUXONB
12SB+
12SB-
12GB
3.3SB+
3.3SB-
MAX5946
23
22
21
20
19
10 11 12 13 14 15 16 17 18
FAULTA
PWRGDA
3.3VAUXOA
3.3VAUXIN
3.3VAUXOB
PWRGDB
FAULTB
3.3GA
SMBus is a trademark of Intel Corp.
PCI Express is a trademark of PCI-SIG Corp.
THIN QFN
________________________________________________________________
Maxim Integrated Products
3.3GB
Typical Application Circuit appears at end of data sheet.
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.
Dual PCI Express, Hot-Plug
Controller
MAX5946
ABSOLUTE MAXIMUM RATINGS
(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
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.
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
12V SUPPLY
12V Supply Voltage Range
12VIN Undervoltage Lockout
12VIN Supply Current
12VIN CONTROL
12VIN Current-Limit
Threshold (V
12S_+
- V
12S_-
)
12G_ Gate Charge Current
12G_ Gate Discharge Current
12G_ Gate High Voltage
(V
12G_
- V
12VIN
)
12G_ Threshold Voltage For
PWRGD_
Assertion (Note 2)
12S_- Input Bias Current
12S_+ Input Bias Current
3.3V SUPPLY
3.3V Supply Voltage Range
Undervoltage Lockout
(Note 3)
V
3.3SA+
,
V
3.3SB+
3.3SA+ rising
Hysteresis
3.0
2.52
3.3
2.65
30
3.6
2.78
V
V
mV
20
V
12ILIM
I
12G_CHG
I
12G_DIS
V
12G_
= GND
Normal turn-off, ON_ = GND, V
12G
_ = 2V
Output short-circuit condition, strong gate pulldown
to regulation, V
12VIN
- V
12S_
≥
1V, V
12G_
= 5V
I
12G_
= 1µA
Referred to V
12VIN
, I
12G_
= 1µA
49
4
50
50
4.8
-3.0
54
5
150
120
5.3
-4
59
6
250
180
5.8
-4.8
1
60
mV
µA
µA
mA
V
V
µA
µA
V
12VIN
V
12UVLO
I
12VIN
10.8
12
10
0.1
0.5
1
13.2
10.5
V
V
mA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
12VIN
rising
Hysteresis
V
12VIN
= 13.2V
9.5
V
12G_H
V
PGTH12
2
_______________________________________________________________________________________
Dual PCI Express, Hot-Plug
Controller
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
3.3V CONTROL
3.3V Current-Limit Threshold
(V
3.3S_+
- V
3.3S_-
)
3.3G_ Gate Charge Current
3.3G_ Gate Discharge
Current
3.3G_ Gate High Voltage
(V
3.3G_
- V
3.3S_+
)
3.3G_ Threshold Voltage For
PWRGD_
Assertion (Note 2)
3.3S_- Input Bias Current
3.3S_+ Input Bias Current
3.3V AUXILIARY SUPPLY
3.3VAUXIN Supply Voltage
Range
3.3VAUXIN Undervoltage
Lockout
3.3VAUXIN Supply Current
3.3VAUXIN to 3.3VAUXO_
Maximum Dropout
3.3VAUXO_ Current-Limit
Threshold
3.3VAUXO_ Threshold For
PWRGD_
Assertion
(V
3.3VAUXIN
- V
3.3VAUXO_
)
(Note 3)
LOGIC SIGNALS
Input-Logic Threshold
(ON_,
FON_,
AUXON_,
PRES-DET_,
INPUT_)
Input Bias Current
(ON_, AUXON_, INPUT_)
FON_, PRES-DET_
Internal
Pullup
ON_, AUXON_ High-to-Low
Deglitch Time
25
50
4
Rising edge
Hysteresis
1.0
25
1
75
2.0
V
mV
µA
kΩ
µs
V
3.3VAUXIN
V
3.3VAUXUVLO
3.3VAUXIN rising
Hysteresis
V
3.3VAUXIN
= 3.6V
I
3.3VAUXO_
= 375mA
3.3VAUXO_ shorted to GND
376
470
3.0
2.52
3.3
2.65
30
1.5
3
225
564
3.6
2.78
V
V
mV
mA
mV
mA
20
V
3.3ILIM
I
3.3G_CHG
I
3.3G_DIS
V
3.3G_
= GND
ON_ = GND, V
3.3G_
= 2V
Output short-circuit condition, strong gate pulldown
to regulation, V
3.3S_+
- V
3.3S_
≥
1V, V
3.3G_
= 5V
Sourcing 1µA
Referred to V
3.3VAUXIN
, I
3.3G_
= 1µA
17
4
50
100
4.5
-3.0
20
5
150
150
5.5
-4
23
6
250
220
6.8
-4.5
1
60
mV
µA
µA
mA
V
V
µA
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX5946
V
3.3G_H
V
PGTH3.3
V
PGTH3.3AUX
400
mV
_______________________________________________________________________________________
3
Dual PCI Express, Hot-Plug
Controller
MAX5946
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
PRES-DET_
High-to-Low
Deglitch Time
PWRGD_
Power-On Reset
Time (Note 2)
PWRGD_
Low-to-High
Deglitch Time
PWRGD_, FAULT_
Output
Low Voltage
PWRGD_, FAULT_
Output-
High Leakage Current
SYMBOL
t
DEG
PORADJ = open
t
POR_HL
R
PORADJ
= 20kΩ
R
PORADJ
= 100kΩ
R
PORADJ
= 200kΩ
t
POR_LH
Sinking 2mA
Sinking 30mA
V
PWRGD_
= V
FAULT_
= 5.5V
TIM = open
FAULT_
Timeout
t
FAULT
R
TIM
= 15kΩ
R
TIM
= 120kΩ
R
TIM
= 300kΩ
FAULT_
Timeout During
Startup
Autorestart Delay Time
Fault Reset Minimum Pulse
Width (Note 4)
Thermal-Shutdown Threshold
Thermal-Shutdown Threshold
Hysteresis
OUTPUT_ Debounce Time
OUTPUT_ High Voltage
OUTPUT_ Low Voltage
t
DBC
Sourcing 2mA
Sinking 2mA
2.6
t
SU
t
RESTART
t
RESET
T
SD
T
J
rising
5.5
1.4
12
11
2.6
22
59
2 x t
FAULT
64 x t
FAULT
100
+150
20
4.4
6.2
ms
ms
µs
°C
°C
ms
V
V
CONDITIONS
MIN
3
90
35
145
TYP
5
160
55
265
570
4
0.1
0.7
1
17.0
3.8
32
ms
µs
V
µA
MAX
7
250
75
380
ms
UNITS
ms
V
3.3VAUXIN
V
3.3VAUXIN
- 0.3
0.4
Note 1:
Note 2:
Note 3:
Note 4:
100% production tested at T
A
= +25°C. Parameters over temperature are guaranteed by design.
PWRGD_
asserts a time t
POR_HL
after V
PGTH12
, V
PGTH3.3
, and V
PGTH3.3AUX
conditions are met.
The UVLO for the 3.3V supply is sensed at 3.3SA+.
This is the time that ON_ or AUXON_ must stay low when resetting a fault condition.
4
_______________________________________________________________________________________
Dual PCI Express, Hot-Plug
Controller
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.)
12VIN INPUT SUPPLY CURRENT
vs. TEMPERATURE
0.505
0.504
0.503
0.502
0.501
0.500
0.499
0.498
0.497
0.496
0.495
0.494
0.493
0.492
0.491
0.490
-40
-15
10
35
60
TEMPERATURE (°C)
MAX5946 toc01
MAX5946
3.3VAUXIN SUPPLY CURRENT
vs. TEMPERATURE
MAX5946 toc02
ON AND AUXON LOW-TO-HIGH THRESHOLD
VOLTAGE vs. TEMPERATURE
1.9
THRESHOLD VOLTAGE (V)
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
ON_ OR AUXON_
MAX5946 toc03
2.0
1.8
1.6
SUPPLY CURRENT (mA)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
2.0
SUPPLY CURRENT (mA)
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
3.3VAUXO_ OUTPUT VOLTAGE vs. CURRENT
MAX5946 toc04
12G_ AND 3.3G_ GATE CHARGE
CURRENT vs. TEMPERATURE
MAX5946 toc05
12G_ AND 3.3G_ GATE DISCHARGE
CURRENT vs. TEMPERATURE
MAX5946 toc06
3.5
3.0
OUTPUT VOLTAGE (V)
2.5
2.0
1.5
1.0
0.5
0
0
0.1
0.2
0.3
0.4
0.5
5.35
5.30
GATE CHARGE CURRENT (µA)
5.25
5.20
5.15
5.10
5.05
5.00
4.95
4.90
4.85
3.3G_
12G_
170
GATE DISCHARGE CURRENT (µA)
165
3.3G_
160
155
12G_
150
145
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
0.6
OUTPUT CURRENT (A)
3.3VAUX INTERNAL SWITCH
MAXIMUM DROPOUT vs. TEMPERATURE
MAX5946 toc07
12V AND 3.3V CURRENT-LIMIT THRESHOLD
VOLTAGE vs. TEMPERATURE
MAX5946 toc08
AUXILIARY CURRENT LIMIT
vs. TEMPERATURE
0.495
AUXILIARY CURRENT LIMIT (A)
0.490
0.485
0.480
0.475
0.470
0.465
0.460
0.455
MAX5946 toc09
0.18
0.16
DROPOUT VOLTAGE (V)
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0
-40
AUXILIARY OUTPUT CURRENT = 375mA
CURRENT-LIMIT THRESHOLD VOLTAGE (mV)
0.20
60
50
40
30
20
10
0
12V CURRENT-SENSE
THRESHOLD
0.500
3.3V CURRENT-SENSE
THRESHOLD
0.450
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
-15
10
35
60
85
TEMPERATURE (°C)
_______________________________________________________________________________________
5
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