MAX5954LETX+T [MAXIM]
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| 型号： | MAX5954LETX+T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 暂无描述 控制器 PC |
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19-3914; Rev 1; 1/06
Single PCI Express, Hot-Plug
Controller
General Description
Features
♦ PCI Express Compliant
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.
♦ 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
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.
♦ 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
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.
♦ Forced-On Input Facilitates Testing
♦ Thermal Shutdown
♦ Allows Control through SMBus with an I/O
Expander
Ordering Information
PIN-
PACKAGE
PKG
CODE
PART
TEMP RANGE
36 Thin QFN
36 Thin QFN
MAX5954AETX+ -40°C to +85°C
MAX5954LETX+ -40°C to +85°C
+Denotes lead free package.
T3666-3
T3666-3
Pin Configuration
TOP VIEW
21 20 19
27 26 25 24 23 22
Applications
28
29
30
31
32
18
17
16
15
14
TIM
N.C.
N.C.
Servers
N.C.
N.C.
N.C.
Desktop Mobile Server Platforms
Workstations
OUTPUT
INPUT
N.C.
3.3VAUXIN
MAX5954
12VIN 33
13 3.3VAUXO
Embedded Devices
34
35
36
12
11
10
GND
PGND
PWRGD
FAULT
3.3G
PORADJ
+
4
5
6
7
8
9
1
2
3
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.
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.
Single PCI Express, Hot-Plug
Controller
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND, unless otherwise noted.)
Continuous Power Dissipation (T = +70°C)
A
12VIN......................................................................-0.3V to +14V
36-Pin Thin QFN (derate 26.3mW/°C above +70°C).....2.105W
12G............................................................-0.3V to (V
+ 6V)
+ 0.3V)
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
12VIN
12S, 12S-, 3.3G ......................................-0.3V to (V
12VIN
3.3VAUXIN, ON, FAULT ..........................................-0.3V to +6V
PWRGD ....................................................................-0.3V to +6V
PGND ....................................................................-0.3V to +0.3V
All Other Pins to GND......................-0.3V to (V
+ 0.3V)
3.3VAUXIN
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
= V
= V
= 12V, V
= V
= V
= V
= V
= V
= 3.3V, PWRGD = FAULT = PORADJ = TIM =
12VIN
12S-
12S+
3.3S+
3.3S-
3.3VAUXIN
ON
AUXON
FON
OUTPUT = 12G = 3.3G = OPEN, INPUT = PRES-DET = PGND = GND, T = -40°C to +85°C, unless otherwise noted. Typical values
A
are at T = +25°C.) (Note 1)
A
PARAMETER
12V SUPPLY
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
12V Supply Voltage Range
V
10.8
9.5
12
10
13.2
10.5
V
V
12VIN
V12VIN rising
Hysteresis
12VIN Undervoltage Lockout
V
12UVLO
0.1
0.5
12VIN Supply Current
I
V
= 13.2V
12VIN
1
mA
12VIN
12VIN CONTROL
12VIN Current-Limit
V
49
54
59
mV
12ILIM
Threshold (V
- V
)
12S+
12S-
12G Gate Charge Current
I
V
= GND
12G
4
5
6
µA
µA
12G_CHG
Normal turn-off, ON = GND, V
= 2V
50
150
250
12G
12G Gate Discharge Current
I
12G_DIS
Output short-circuit condition, strong gate pulldown
to regulation, V - V ≥ 1V, V = 5V
50
4.8
3.0
120
5.3
4
180
5.8
4.8
mA
V
12VIN
12S_
12G_
12G Gate High Voltage
V
I
= 1µA
12GH
12G
(V
12G
- V
)
12VIN
12G Threshold Voltage For
PWRGD Assertion
V
Referred to V
, I = 1µA (Note 2)
12VIN 12G_
V
PGTH12
12S- Input Bias Current
12S+ Input Bias Current
3.3V SUPPLY
1
µA
µA
20
60
3.3V Supply Voltage Range
V
3.0
3.3
2.65
30
3.6
V
V
3.3S+
3.3S+ rising
Hysteresis
2.52
2.78
Undervoltage Lockout
(Note 3)
mV
2
_______________________________________________________________________________________
Single PCI Express, Hot-Plug
Controller
ELECTRICAL CHARACTERISTICS (continued)
(V
= V
= V
= 12V, V
= V
= V
= V
= V
= V
= 3.3V, PWRGD = FAULT = PORADJ = TIM =
12VIN
12S-
12S+
3.3S+
3.3S-
3.3VAUXIN
ON
AUXON
FON
OUTPUT = 12G = 3.3G = OPEN, INPUT = PRES-DET = PGND = GND, T = -40°C to +85°C, unless otherwise noted. Typical values
A
are at T = +25°C.) (Note 1)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
3.3V CONTROL
3.3V Current-Limit Threshold
V
17
20
23
mV
3.3ILIM
(V
3.3S+
- V
)
3.3S-
3.3G Gate Charge Current
I
V
= GND
3.3G
4
5
6
µA
µA
3.3G CHG
ON = GND, V
= 2V
50
150
250
3.3G
3.3G Gate Discharge Current
I
3.3G_DIS
Output short-circuit condition, strong gate pulldown
100
4.5
150
5.5
+4
220
6.8
mA
V
to regulation, V
- V
3.3S
≥ 1V, V
= 5V
3.3G
3.3S+
3.3G Gate High Voltage
V
Sourcing 1µA
3.3G_H
(V
3.3G
- V
)
3.3S+
3.3G Threshold Voltage For
PWRGD Assertion
V
Referred to V
, I = 1µA (Note 2)
3.3VAUXIN 3.3G
-3.0
+4.5
V
PGTH3.3
3.3S- Input Bias Current
3.3S+ Input Bias Current
3.3V AUXILIARY SUPPLY
1
µA
µA
20
60
3.3VAUXIN Supply Voltage
Range
V
3.0
3.3
3.6
V
3.3VAUXIN
3.3VAUXIN rising
Hysteresis
2.52
2.65
30
2.78
V
3.3VAUXIN Undervoltage
Lockout
V
3.3VAUXUVLO
mV
mA
3.3VAUXIN Supply Current
V
= 3.6V
1.5
3
3.3VAUXIN
3.3VAUXIN to 3.3VAUXO
Maximum Dropout
I
= 375mA
225
mV
mA
3.3VAUXO
3.3VAUXO Current-Limit
Threshold
3.3VAUXO shorted to GND
(Note 3)
376
470
564
400
3.3VAUXO Threshold For
PWRGD Assertion
V
mV
PGTH3.3AUX
(V
- V
)
3.3VAUXO
3.3VAUXIN
LOGIC SIGNALS
Input-Logic Threshold
(ON, FON, AUXON,
PRES-DET, INPUT)
Rising edge
Hysteresis
1.0
25
2.0
V
25
mV
Input Bias Current
(ON, AUXON, INPUT)
1
µA
kΩ
µs
FON, PRES-DET Internal
Pullup
50
4
75
ON, AUXON High-to-Low
Deglitch Time
_______________________________________________________________________________________
3
Single PCI Express, Hot-Plug
Controller
ELECTRICAL CHARACTERISTICS (continued)
(V
= V
= V
= 12V, V
= V
= V
= V
= V
= V
= 3.3V, PWRGD = FAULT = PORADJ = TIM =
12VIN
12S-
12S+
3.3S+
3.3S-
3.3VAUXIN
ON
AUXON
FON
OUTPUT = 12G = 3.3G = OPEN, INPUT = PRES-DET = PGND = GND, T = -40°C to +85°C, unless otherwise noted. Typical values
A
are at T = +25°C.) (Note 1)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
PRES-DET High-to-Low
Deglitch Time
t
3
5
7
ms
DEG
PORADJ = open
90
35
160
55
250
75
R
R
R
= 20kΩ
PWRGD Power-On Reset
Time (Note 2)
PORADJ
PORADJ
PORADJ
t
t
ms
POR_HL
POR_LH
= 100kΩ
= 200kΩ
145
265
570
380
PWRGD Low-to-High Deglitch
Time
4
µs
V
Sinking 2mA
Sinking 30mA
0.1
0.7
PWRGD, FAULT Output Low
Voltage
PWRGD, FAULT Output-High
Leakage Current
V
= V
= 5.5V
FAULT
1
µA
PWRGD
TIM = open
5.5
1.4
12
11
2.6
22
59
17.0
3.8
32
R
TIM
R
TIM
R
TIM
= 15kΩ
FAULT Timeout
t
ms
FAULT
= 120kΩ
= 300kΩ
FAULT Timeout During
Startup
t
2 x t
ms
ms
µs
°C
°C
ms
V
SU
FAULT
Autorestart Delay Time
t
64 x t
FAULT
RESTART
Fault Reset Minimum Pulse
Width
t
(Note 4)
100
RESET
Thermal-Shutdown Threshold
T
T rising
J
+150
20
SD
Thermal-Shutdown Threshold
Hysteresis
OUTPUT Debounce Time
OUTPUT High Voltage
OUTPUT Low Voltage
t
2.6
4.4
6.2
DBC
V
3.3VAUXIN
- 0.3
Sourcing 2mA
Sinking 2mA
V
3.3VAUXIN
0.4
V
Note 1: 100% production tested at T = +25°C. Parameters over temperature are guaranteed by design.
A
Note 2: PWRGD asserts a time t
after V
, V
, and V
conditions are met.
POR_HL
PGTH12 PGTH3.3
PGTH3.3AUX
Note 3: The UVLO for the 3.3V supply is sensed at 3.3S+.
Note 4: This is the time that ON or AUXON must stay low when resetting a fault condition.
4
_______________________________________________________________________________________
Single PCI Express, Hot-Plug
Controller
Typical Operating Characteristics
(V
= V
= 12V, V
= V
= V
= V
= V
= 3.3V, PRES-DET = GND, FON = PORADJ = TIM = float,
INPUT
12VIN
12S+
3.3VAUXIN
3.3S+
ON
AUXON
FAULT = 10kΩ to 3.3VAUXIN, PWRGD = 10kΩ to 3.3VAUXO, T = +25°C, unless otherwise noted, see the Typical Application
A
Circuit.)
3.3VAUXIN SUPPLY CURRENT
vs. TEMPERATURE
ON AND AUXON LOW-TO-HIGH THRESHOLD
VOLTAGE vs. TEMPERATURE
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
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
2.0
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
-40
-15
10
35
60
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
12G AND 3.3G GATE CHARGE
CURRENT vs. TEMPERATURE
12G AND 3.3G GATE DISCHARGE
CURRENT vs. TEMPERATURE
3.3VAUXO OUTPUT VOLTAGE vs. CURRENT
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
5.35
5.30
5.25
5.20
5.15
5.10
5.05
5.00
4.95
4.90
4.85
170
165
160
155
150
145
12G
3.3G
12G
3.3G
0
0.1
0.2
0.3
0.4
0.5
0.6
-40
-15
10
35
60
85
-40
-15
10
35
60
85
OUTPUT CURRENT (A)
TEMPERATURE (°C)
TEMPERATURE (°C)
3.3VAUX INTERNAL SWITCH
MAXIMUM DROPOUT vs. TEMPERATURE
12V AND 3.3V CURRENT-LIMIT THRESHOLD
VOLTAGE vs. TEMPERATURE
AUXILIARY CURRENT LIMIT
vs. TEMPERATURE
0.20
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0
60
0.500
0.495
0.490
0.485
0.480
0.475
0.470
0.465
0.460
0.455
0.450
AUXILIARY OUTPUT CURRENT = 375mA
50
40
30
20
10
0
12V CURRENT-SENSE
THRESHOLD
3.3V CURRENT-SENSE
THRESHOLD
-40
-15
10
35
60
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
_______________________________________________________________________________________
5
Single PCI Express, Hot-Plug
Controller
Typical Operating Characteristics (continued)
(V
= V
= 12V, V
= V
= V
= V
= V
= 3.3V, PRES-DET = GND, FON = PORADJ = TIM = float,
INPUT
12VIN
12S+
3.3VAUXIN
3.3S+
ON
AUXON
FAULT = 10kΩ to 3.3VAUXIN, PWRGD = 10kΩ to 3.3VAUXO, T = +25°C, unless otherwise noted, see the Typical Application
A
Circuit.)
3.3VAUXIN UNDERVOLTAGE-LOCKOUT
THRESHOLD vs. TEMPERATURE
12VIN UNDERVOLTAGE-LOCKOUT
THRESHOLD vs. TEMPERATURE
10.20
10.15
10.10
10.05
10.00
9.95
2.70
2.68
2.66
2.64
2.62
2.60
9.90
9.85
9.80
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
12V TURN-ON/OFF TIME
3.3V TURN-ON/OFF TIME
MAX5954 toc13
MAX5954 toc12
3.3V OUTPUT
5V/div
12V OUTPUT
10V/div
3.3G
10V/div
12G
20V/div
ON
ON
5V/div
5V/div
PWRGD
5V/div
PWRGD
5V/div
40ms/div
40ms/div
3.3V AUXILIARY TURN-ON/OFF TIME
12V POWER-UP
MAX5954 toc15
MAX5954 toc14
3.3AUXO
OUTPUT VOLTAGE
2V/div
12G
20V/div
12V OUTPUT
10V/div
PWRGD
2V/div
12VIN, 12V INPUT
10V/div
AUXON
2V/div
PWRGD
5V/div
40ms/div
40ms/div
6
_______________________________________________________________________________________
Single PCI Express, Hot-Plug
Controller
Typical Operating Characteristics (continued)
(V
= V
= 12V, V
= V
= V
= V
= V
= 3.3V, PRES-DET = GND, FON = PORADJ = TIM = float,
INPUT
12VIN
12S+
3.3VAUXIN
3.3S+
ON
AUXON
FAULT = 10kΩ to 3.3VAUXIN, PWRGD = 10kΩ to 3.3VAUXO, T = +25°C, unless otherwise noted, see the Typical Application
A
Circuit.)
TURN-ON DELAY 3.3V OUTPUT AND
3.3V INPUT/3.3V AUXILIARY INPUT
3.3V AUXILIARY OUTPUT
POWER-UP
MAX5954 toc16
MAX5954 toc17
3.3G
10V/div
3.3VAUXO
OUTPUT VOLTAGE
5V/div
3.3V OUTPUT
5V/div
3.3 INPUT,
3.3VAUXIN
5V/div
5V/div
3.3S+
5V/div
3.3 VOLTAGE
PWRGD
3.3G
3.3VAUXO
5V/div
5V/div
10V/div
PWRGD
5V/div
4ms/div
100ms/div
FAULT CONDITION ON 12V OUTPUT
FAULT CONDITION ON 3.3V OUTPUT
(AUTORESTART OPTION MAX5954A)
(AUTORESTART OPTION MAX5954A)
MAX5954 toc18
MAX5954 toc19
R
STEP TO 1.5Ω
R
STEP TO 0.5Ω
LOAD
LOAD
12V OUTPUT CURRENT
5A/div
3.3V MAIN OUTPUT CURRENT
2A/div
12G
20V/div
3.3G
10V/div
12V OUTPUT VOLTAGE
10V/div
3.3V OUTPUT VOLTAGE
5V/div
t
t
RESTART
FAULT
5V/div
RESTART
FAULT
5V/div
100ms/div
100ms/div
FAULT CONDITION ON 12V OUTPUT
(LATCH OPTION MAX5954L)
FAULT CONDITION ON AUXILIARY OUTPUT
(AUTORESTART OPTION MAX5954A)
MAX5954 toc21
MAX5954 toc20
R
STEP TO 1.5Ω
R
STEP TO 4Ω
LOAD
LOAD
12V OUTPUT CURRENT
5A/div
3.3VAUXO OUTPUT CURRENT
500mA/div
12G
20V/div
12V OUTPUT VOLTAGE
10V/div
3.3VAUXO OUTPUT VOLTAGE
2V/div
t
RESTART
FAULT
5V/div
FAULT
2V/div
100ms/div
100ms/div
_______________________________________________________________________________________
7
Single PCI Express, Hot-Plug
Controller
Typical Operating Characteristics (continued)
(V
= V
= 12V, V
= V
= V
= V
= V
= 3.3V, PRES-DET = GND, FON = PORADJ = TIM = float,
INPUT
12VIN
12S+
3.3VAUXIN
3.3S+
ON
AUXON
FAULT = 10kΩ to 3.3VAUXIN, PWRGD = 10kΩ to 3.3VAUXO, T = +25°C, unless otherwise noted, see the Typical Application
A
Circuit.)
FAULT CONDITION ON 3.3V OUTPUT
FAULT CONDITION ON 12V OUTPUT
(LATCH OPTION MAX5954)
MAX5954 toc22
MAX5954 toc23
R
LOAD
R
STEP TO 0.5Ω
LOAD
STEP TO 1.5Ω
12V OUTPUT CURRENT
5A/div
3.3V OUTPUT CURRENT
2A/div
t
FAULT
12G
20V/div
3.3G
10V/div
12V OUTPUT VOLTAGE
10V/div
3.3V OUTPUT VOLTAGE
5V/div
FAULT
5V/div
FAULT
5V/div
4ms/div
100ms/div
FAULT CONDITION ON AUXILIARY OUTPUT
FAULT CONDITION ON 3.3V MAIN OUTPUT
(LATCH OPTION MAX5954)
MAX5954 toc24
MAX5954 toc25
R
STEP TO 4Ω
LOAD
3.3V OUTPUT CURRENT
2A/div
3.3VAUXO OUTPUT CURRENT
500mA/div
R
LOAD
STEP TO 0.5Ω
t
FAULT
3.3G
10V/div
3.3VAUXO OUTPUT VOLTAGE
2V/div
3.3V OUTPUT VOLTAGE
5V/div
FAULT
2V/div
FAULT
5V/div
4ms/div
100ms/div
SHORT CIRCUIT ON 12V OUTPUT
FAULT CONDITION ON AUXILIARY OUTPUT
MAX5954 toc27
MAX5954 toc26
R
LOAD
STEP TO 4Ω
12V OUTPUT CURRENT
5A/div
3.3VAUXO OUTPUT CURRENT
500mA/div
t
FAULT
12G
20V/div
3.3VAUXO OUTPUT VOLTAGE
2V/div
12V OUTPUT VOLTAGE
10V/div
FAULT
2V/div
FAULT
5V/div
2ms/div
4ms/div
8
_______________________________________________________________________________________
Single PCI Express, Hot-Plug
Controller
Typical Operating Characteristics (continued)
(V
= V
= 12V, V
= V
= V
= V
= V
= 3.3V, PRES-DET = GND, FON = PORADJ = TIM = float,
INPUT
12VIN
12S+
3.3VAUXIN
3.3S+
ON
AUXON
FAULT = 10kΩ to 3.3VAUXIN, PWRGDA = 10kΩ to 3.3VAUXO, T = +25°C, unless otherwise noted, see the Typical Application
A
Circuit.)
SHORT CIRCUIT ON 12V OUTPUT
SHORT CIRCUIT ON 3.3V OUTPUT
MAX5954 toc28
MAX5954 toc29
3.3V OUTPUT CURRENT
2A/div
12V OUTPUT CURRENT
25A/div
12G
20V/div
0V
3.3G
5V/div
12V OUTPUT VOLTAGE
10V/div
0V
3.3V OUTPUT VOLTAGE
5V/div
FAULT
5V/div
0V
FAULT
5V/div
4µs/div
2ms/div
SHORT CIRCUIT ON 3.3AUXO_
SHORT CIRCUIT ON 3.3V OUTPUT
MAX5954 toc31
MAX5954 toc30
3.3VAUXO OUTPUT CURRENT
500mA/div
3.3V OUTPUT CURRENT
10A/div
3.3VAUXO OUTPUT VOLTAGE
2V/div
3.3G
5V/div
3.3V OUTPUT VOLTAGE
5V/div
FAULT
5V/div
FAULT
5V/div
0V
2ms/div
2µs/div
POWER-UP INTO FAULT
(AUXILIARY SUPPLY)
SHORT CIRCUIT ON 3.3VAUXO_
MAX5954 toc32
MAX5954 toc33
R
= 4Ω
LOAD
3.3VAUXO OUTPUT CURRENT
5A/div
3.3VAUXO OUTPUT CURRENT
500mA/div
t
SU
3.3VAUXO OUTPUT VOLTAGE
2V/div
3.3VAUXO OUTPUT VOLTAGE
2V/div
AUXON
5V/div
FAULT
5V/div
FAULT
5V/div
2µs/div
4ms/div
_______________________________________________________________________________________
9
Single PCI Express, Hot-Plug
Controller
Typical Operating Characteristics (continued)
(V
= V
= 12V, V
= V
= V
= V
= V
= 3.3V, PRES-DET = GND, FON = PORADJ = TIM = float,
INPUT
12VIN
12S+
3.3VAUXIN
3.3S+
ON
AUXON
FAULT = 10kΩ to 3.3VAUXIN, PWRGDA = 10kΩ to 3.3VAUXO, T = +25°C, unless otherwise noted, see the Typical Application
A
Circuit.)
POWER-UP INTO FAULT
(3.3V MAIN)
POWER-UP INTO FAULT
(12V OUTPUT)
MAX5954 toc34
MAX5954 toc35
R
= 0.5Ω
LOAD
3.3V OUTPUT CURRENT
4A/div
12V OUTPUT CURRENT
5A/div
t
t
SU
SU
3.3G
5V/div
12G
10V/div
3.3V OUTPUT VOLTAGE
2V/div
12V OUTPUT VOLTAGE
10V/div
ON, AUXON
5V/div
ON, AUXON
5V/div
FAULT
5V/div
FAULT
5V/div
4ms/div
4ms/div
PRESENT-DETECT (ON/OFF) OPERATION
PRESENT-DETECT (ON/OFF) OPERATION
MAX5954 toc37
MAX5954 toc36
12V OUTPUT VOLTAGE
10V/div
12V OUTPUT VOLTAGE
10V/div
3.3VAUXO
OUTPUT VOLTAGE
3.3VAUXO
OUTPUT VOLTAGE
5V/div
5V/div
5V/div
5V/div
PWRGD
PWRGD
PRES-DET
PRES-DET
5V/div
5V/div
4ms/div
40ms/div
FORCED-ON (ON/OFF) OPERATION
FORCED-ON (ON/OFF) OPERATION
MAX5954 toc38
MAX5954 toc39
12V OUTPUT VOLTAGE
12V OUTPUT VOLTAGE
10V/div
10V/div
3.3VAUXO
OUTPUT VOLTAGE
3.3VAUXO
OUTPUT VOLTAGE
5V/div
5V/div
5V/div
5V/div
PWRGD
FON
PWRGD
FON
5V/div
5V/div
40ms/div
4ms/div
10 ______________________________________________________________________________________
Single PCI Express, Hot-Plug
Controller
Typical Operating Characteristics (continued)
(V
= V
= 12V, V
= V
= V
= V
= V
= 3.3V, PRES-DET = GND, FON = PORADJ = TIM = float,
INPUT
12VIN
12S+
3.3VAUXIN
3.3S+
ON
AUXON
FAULT = 10kΩ to 3.3VAUXIN, PWRGDA = 10kΩ to 3.3VAUXO, T = +25°C, unless otherwise noted, see the Typical Application
A
Circuit.)
POWER-ON RESET TIME
vs. PORADJ RESISTOR
DEBOUNCED ON/OFF OPERATION
MAX5954 toc40
1600
1400
1200
1000
800
600
400
200
0
INPUT
2V/div
OUTPUT
2V/div
0
50 100 150 200 250 300 350 400 450 500
10ms/div
R
(KΩ)
PORADJ
t
TIME DELAY
FAULT
vs. TIM RESISTOR
120
100
80
60
40
20
0
0
50 100 150 200 250 300 350 400 450 500
(kΩ)
R
TIM
______________________________________________________________________________________ 11
Single PCI Express, Hot-Plug
Controller
Pin Description
PIN
NAME
FUNCTION
Present-Detect Input. PRES-DET accepts inputs from the PRSNT#2 pin on a PCI-E connector. PRES-DET
has an internal pullup to 3.3VAUXIN. When PRES-DET is low, the outputs follow the command from ON
and AUXON after a 4ms debounced time. When PRES-DET goes from low to high, all outputs of the
respective slot shut down with no delay (see Table 2).
1
PRES-DET
Forced-On Input. FON has a 50kΩ internal pullup to 3.3VAUXIN. A logic-low on FON turns on all PCI-E
outputs as long as the power inputs are within their operating range, regardless of the status of the other
input signals. Leave FON open for normal operation (see Table 2).
2
FON
3
4
ON
12V and 3.3V Outputs Enable. A logic-high at ON turns on the 12V and 3.3V outputs (see Table 2).
3.3V Auxiliary Output Enable. A logic-high at AUXON turns on the auxiliary output (3.3VAUXO) (see Table 2).
AUXON
12V Positive Current-Sense Input. Connect the positive terminal of the current-sense resistor to 12S+
using the Kelvin-sensing technique to assure accurate current sensing.
5
6
7
12S+
12S-
12G
12V Negative Current-Sense Input. Connect 12S- to the negative side of the current-sense resistor using
the Kelvin-sensing technique to assure accurate current sensing.
12V Gate-Drive Output. Connect 12G to the gate of the 12V MOSFET. At power-up, V
is raised to the internal charge-pump voltage level by a constant current.
12G
3.3V Positive Current-Sense Input. Connect the positive side of the current-sense resistor to 3.3S+ using
the Kelvin-sensing technique to assure accurate current sensing. This input is also used for the 3.3V
supply’s UVLO function.
8
3.3S+
3.3V Negative Current-Sense Input. Connect to the negative side of the sense resistor using the Kelvin-
sensing technique to assure accurate current sensing.
9
3.3S-
3.3G
3.3V Gate-Drive Output. Connect 3.3G to the gate of the 3.3V MOSFET. At power-up, V
3.3G
10
is charged to 5.5V above the 3.3V supply by a constant current derived from V
.
12VIN
Open-Drain Fault Output Signal. FAULT latches active low whenever the outputs are shut down
due to a fault. A fault is either of:
• An overcurrent condition lasting longer than the overcurrent timeout.
• A device over temperature condition.
11
FAULT
If the fault is detected in the main outputs, FAULT must be reset by toggling the ON input. If the fault is in
the auxiliary output, FAULT must be reset by toggling both ON and AUXON. For the auto-restart version,
FAULT is reset when the part initiates the next power-on cycle.
Open-Drain Power-Good Output. PWRGD goes low t
the power MOSFETs are fully enhanced.
after all outputs reach their final value and
POR_HL
12
13
PWRGD
3.3VAUXO 3.3V Auxiliary Power-Supply Output
3.3V Auxiliary Supply Input. 3.3VAUXIN is the input to a charge pump that drives the internal MOSFET
14
3.3VAUXIN connecting 3.3VAUXIN to 3.3VAUXO. V
analog references of the MAX5954.
is also used to power the internal control logic and
3.3VAUXIN
15–23,
26, 27,
29, 30
N.C.
T1
No Connection. Not internally connected.
Test Input. Connect T1 to GND.
24
12 ______________________________________________________________________________________
Single PCI Express, Hot-Plug
Controller
Pin Description (continued)
PIN
NAME
FUNCTION
25
T2
Test Input. Connect T2 to GND.
Overcurrent Timeout Programming Input. Connect a resistor between 500Ω and 500kΩ from TIM to GND
to program t . Leave TIM floating for a default timeout of 11ms.
28
TIM
FAULT
31
32
OUTPUT
INPUT
Digital Output. 4ms debounced digital output of INPUT.
Digital Logic Gate Input
12V Supply Input. V
charge pump that drives the gate of the MOSFET connected to 12G.
drives the gate of the MOSFET connected to 3.3G. 12VIN powers an internal
12VIN
33
12VIN
34
35
GND
Ground
PGND
Power Ground. Connect externally to GND.
Power-On-Reset Programming Input. Connect a resistor between 500Ω and 500kΩ from PORADJ to GND
to program the POR timing. Leave floating for a default value of 160ms.
36
PORADJ
off while the MAX5954A automatically restarts after a
restart time delay.
Detailed 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
single PCI Express 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. An integrated
debounced attention switch and present-detect signals
are included to simplify system design.
The power requirement for PCI Express connectors is
defined by the PCI Express card specification and
summarized in Table 1.
Startup
The main supply outputs can become active only after
all the following events have occurred:
•
•
V
is above its UVLO threshold
3.3VAUXIN
V
and V
are both above their UVLO
12VIN
3.3S+
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 pumps pro-
vides a gate drive for the 12V output while the gate
drive of the 3.3V output is driven by the 12V input sup-
ply. The 3.3V auxiliary output is completely indepen-
dent from the main outputs with its own charge pump.
threshold
•
•
ON is driven high
PRES-DET is low for more than 5ms
The auxiliary supply output is made available only after
the following events have occurred:
•
•
•
V
is above its UVLO threshold
3.3VAUXIN
At power-up, the MAX5954 keeps all of the external
MOSFETs off until all supplies rise above their respec-
tive UVLO thresholds. The device keeps the internal
MOSFET off only until the 3.3VAUXIN supply rises
above its UVLO threshold. Upon a turn-on command,
the MAX5954 enhances the external 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 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 MAX5954L latches
AUXON is driven high
PRES-DET is low for more than 5ms
The FON input overrides all other control signals and
turns on the PCI Express slot when driven low, as long
as the UVLO thresholds have been reached. Table 2
summarizes the logic conditions required for startup.
The auxiliary supply input powers the internal control
logic and analog references of the MAX5954, so the
main supplies cannot be enabled if V
present.
is not
3.3VAUXIN
When an output is enabled, a programmable startup
timer (t ) begins to count the startup time duration.
SU
The value of t
is set to 2x the fault timeout period
SU
______________________________________________________________________________________ 13
Single PCI Express, Hot-Plug
Controller
R
TIM
R
PORADJ
IN
OUT
12VIN
PWRGD
FAULT
PORADJ
TIM
12S+
+
-
+
-
54mV
R
SENSE12
108mV
12S-
12G
CHARGE
PUMP
5µA
10µA
t
FAULT
DEBOUNCE
OSCILLATOR
t
0
100mA
POR
FAST
OSCILLATOR
OSCILLATOR
150µA
40mV
3.3S+
+
-
+
R
20mV
SENSE3.3
-
3.3S-
3.3G
5µA
10µA
BIAS, REFERENCES
AND UVLO
CONTROL LOGIC
MAIN-CHANNEL
0
150mA
150µA
3.3V
AUXIN
VREF
MAX5954
+
-
CHARGE
PUMP
CONTROL LOGIC
AUX-CHANNEL
UVLO
3.3AUXO
INPUT COMPARATORS AND CHIP CONTROL LOGIC
ON
AUXON
FON
PRES-DET
PGND
GND
Figure 1. Functional Diagram
14 ______________________________________________________________________________________
Single PCI Express, Hot-Plug
Controller
Table 1. Power Requirements for PCI Express Connectors
POWER RAIL
X1 CONNECTOR
X4/8 CONNECTOR
X16 CONNECTOR
3.3V
Voltage Tolerance
Supply Current
9% (max)
3.0A (max)
9% (max)
3.0A (max)
9% (max)
3.0A (max)
Capacitive Load
1000µF (max)
1000µF (max)
1000µF (max)
12V
Voltage Tolerance
Supply Current
8% (max)
0.5A (max)
300µF (max)
8% (max)
2.1A (max)
8% (max)
5.5A (max)
Capacitive Load
1000µF (max)
2000µF (max)
3.3V AUXILIARY
Voltage Tolerance
Supply Current, Wake Enabled
Supply Current, Non-Wake Enabled
9% (max)
375mA (max)
20mA (max)
150µF (max)
9% (max)
375mA (max)
20mA (max)
150µF (max)
9% (max)
375mA (max)
20mA (max)
150µF (max)
Capacitive Load
Table 2. Control Logic Truth Table
3.3VAUXO
AUXILIARY
OUTPUT
12V AND 3.3V
OUTPUTS
ON
AUXON
FON
PRES-DET
X
X
Low
High
High
High
High
High
X
On
Off
Off
On
Off
On
On
Off
Off
Off
On
On
X
X
High
Low*
Low*
Low*
Low*
Low
High
Low
High
Low
Low
High
High
*PRES-DET high-to-low transition has a 5ms delay (t
).
DEG
(t
). R
externally connected from TIM to GND
TIM
output current exceeds the overcurrent threshold
for longer than t . A fault on an auxiliary channel
FAULT
sets the duration of t
.
FAULT
FAULT
causes all supplies to be disabled after a programmable
time period t (see the Fault Management section).
12V and 3.3V Outputs Normal Operation
The MAX5954 monitors and actively limits the current of
the 12V and 3.3V outputs after the startup period. Each
output has its own overcurrent threshold. If any of the
monitored output currents rise above the overcurrent
FAULT
PWRGD
Power-Good (
Power-good (PWRGD) is an open-drain output that
pulls low a time (t ) after all of the outputs are
)
POR_HL
threshold for a period t
, FAULT asserts and the
fully on. All outputs are considered fully on when 3.3G
has risen to V , 12G has risen to V , and
FAULT
controller disengages both the 12V and 3.3V outputs
(see the Fault Management section).
PGTH3.3
is less than V
PGTH12
V
. t
is
3.3AUXO
PGTH3.3AUX POR_HL
adjustable from 2.5ms to 1.5s by connecting a resistor
3.3V Auxiliary Output Normal Operation
The auxiliary output current is internally monitored and
actively limited to the maximum current-limit value. An
overcurrent fault condition occurs when the
from PORADJ to GND. See the Setting the Power-On-
Reset Timeout Period (t
) section.
POR
______________________________________________________________________________________ 15
Single PCI Express, Hot-Plug
Controller
ON
ON, AUXON
V
V
PGTH12
PGTH3.3
V
V
ON_,TH
ON_,TH
12G, 3.3G
12G
V
12ILIM,TH
12VO, 3.3VO
3.3VAUXO
R
SENSE
12V OUTPUT
CURRENT
3.3VAUXO
PWRGD
V
PGTH3.3AUX
t
POR_HL
PWRGD
FAULT
2 x t
FAULT
3.3VAUXIN
RISING
EDGE
3.3AUXIN
RISING
EDGE
FAULT
PWRGD IS PULLED UP TO 3.3VAUXO.
FAULT IS PULLED UP TO 3.3VAUXIN.
A FAULT ON THE 3.3V OUTPUT OR 3.3VAUXO OUTPUT PRODUCES SIMILAR RESULTS.
PWRGD IS PULLED UP TO 3.3.
FAULT IS PULLED UP TO 3.3AUXIN.
Figure 2. Power-Up Timing, No Fault
Figure 3. 12V Power-Up Timing (Turn-On into Output
Overcurrent/Short Circuit)
Fault Management
A fault occurs when an overcurrent lasts longer then
t
or when the device experiences an overtemper-
FAULT
ature condition.
•
•
A fault on a main output (12V or 3.3V) shuts down
both main outputs. The 3.3V auxiliary is not affected.
12G
V
12ILIM,TH
R
SENSE
A fault on the 3.3V auxiliary output shuts down all
three outputs.
12V OUTPUT
CURRENT
PWRGD
The MAX5954A automatically restarts from a fault shut-
down after the t period, while the MAX5954L
RESTART
latches off. If an overcurrent fault occurred on a main
output, bring ON low for at least t (100µs) and
RESET
t
high again to reset the fault and restart the outputs. If
the overcurrent fault occurred on an auxiliary output or
an overtemperature fault occurred, bring both ON and
FAULT
FAULT
AUXON low for a minimum of t
to reset the fault.
PWRGD IS PULLED UP TO 3.3VAUXO.
FAULT IS PULLED UP TO 3.3VAUXIN.
A FAULT ON THE 3.3V OUTPUT OR 3.3VAUXO OUTPUT PRODUCES SIMILAR RESULTS.
RESET
Bring ON and/or AUXON high again to restart the
respective outputs. As an extra protection, the
MAX5954L waits a minimum of t
be restarted.
before it can
RESTART
Figure 4. 12V Output Overcurrent/Short Circuit During Normal
Operation
Debounced Logic Gate
(Input and Output)
Thermal Shutdown
INPUT accepts an input from a mechanical switch. The
corresponding output (OUTPUT) is debounced for
4.4ms. When INPUT goes from high to low, OUTPUT
goes low right away and stays low for at least 4.4ms.
After the debounce time OUTPUT follows INPUT. If INPUT
goes from low to high, OUTPUT goes high right away and
When the die temperature goes above +150°C (T ), an
SD
overtemperature fault occurs and the MAX5954 shuts
down all outputs. The device waits for the junction temper-
ature to decrease below T - Hysteresis before entering
SD
fault management (see the Fault Management section).
16 ______________________________________________________________________________________
Single PCI Express, Hot-Plug
Controller
stays high for at least 4ms. After the debounce time,
OUTPUT follows INPUT. Figure 5 shows the timing dia-
gram describing the INPUT/OUTPUT debounced feature.
Undervoltage-Lockout Threshold
The UVLO thresholds prevent the internal auxiliary
MOSFET and the external main channel MOSFETs (Q1
and Q2 in the Typical Application Circuit) from turning
Present-Detect and Forced-On Inputs
on if V
, V
, and V
are not present.
3.3VAUXIN
12VIN 3.3VIN
PRES-DET, FON
(
)
Internal comparators monitor the main supplies and the
auxiliary supply and keep the gate-drive outputs (12G
and 3.3G) low until the supplies rise above their UVLO
threshold. The 12V main supply is monitored at 12VIN
and has a UVLO threshold of 10V. The 3.3V main sup-
ply is monitored at 3.3S+ and has a UVLO threshold of
2.65V. The auxiliary supply is monitored at 3.3VAUXIN
and has a 2.65V UVLO threshold. For the main outputs to
PRES-DET input detects the PRSNT#2 pin on a PCI
Express connector. When the card is plugged in,
PRES-DET goes low and allows the turn-on of the out-
put after a 4ms debounced time. When the card is
removed, an internal 50kΩ pullup forces PRES-DET
high and the PCI Express slot is shut down with no
delay. PRES-DET works in conjunction with ON and
AUXON and only enables the device when ON and
AUXON are high.
operate, V
must be above its UVLO threshold.
3.3VAUXIN
External MOSFET Gate Driver
(12G and 3.3G)
A logic-low on FON forces the PCI Express slot (main
supplies and auxiliary) to turn on regardless of the sta-
tus of the other logic inputs provided the UVLO thresh-
olds are exceeded on all of the inputs.
The gate drive for the external MOSFETs is provided at
12G and 3.3G. 12G is the gate drive for the 12V main
supply and is boosted to 5.3V above V
by an
12VIN
Active Current Limits
Active current limits are provided for all three outputs.
Connect a current-sense resistor between 12S+ and
12S- to set the current limit for the 12V output. The cur-
internal charge pump. During turn-on, 12G sources
5µA into the external gate capacitance to control the
turn-on time of the external MOSFET. During turn-off,
12G sinks 150µA from the external gate capacitance to
quickly turn off the external MOSFET. During short-cir-
cuit events, an internal 120mA current activates to
rapidly bring the load current into the regulation limits.
rent limit is set to 54mV/R
. Connect a
SENSE12
current-sense resistor between 3.3S+ and 3.3S- to
set the current limit for the 3.3V main output to
20mV/R
For the auxiliary output (3.3V
)
SENSE3.3.
the current limit is fixed at 470mA.
AUXO
3.3G is the gate drive for the 3.3V main supply’s
MOSFET and is driven to 5.5V above the 3.3V main sup-
ply. The power for 3.3G is supplied from 12VIN and has
no internal charge pump. During turn-on, 3.3G sources
5µA into the external gate capacitance to control the
turn-on time of the external MOSFET. During turn-off,
3.3G sinks 150µA to quickly turn off the external
MOSFET. During short-circuit events, an internal 150mA
current activates to rapidly turn off the external
MOSFET.
When the voltage across R
or R
SENSE12
SENSE3.3
reaches the current-limit threshold voltage, the
MAX5954 regulates the gate voltage to maintain the
current-limit threshold voltage across the sense resis-
tor. If the current limit lasts for t
, then an overcur-
FAULT
rent fault occurs. The MAX5954 shuts down both the
12V and 3.3V outputs and asserts the FAULT output.
When the auxiliary output reaches the current limit
(470mA) for longer than t
, a fault occurs and the
FAULT
Auxiliary Supply (3.3VAUXIN)
3.3VAUXIN provides power to the auxiliary output as
well as the internal logic and references. The drain of the
internal auxiliary MOSFET connects to 3.3VAUXIN
through internal sense resistor and the source connects
to the auxiliary output 3.3VAUXO. The MOSFET’s typical
on-resistance is 0.3Ω. An internal charge pump boosts
the gate-drive voltage to fully turn on the internal n-chan-
nel MOSFET. The auxiliary supply has an internal current
limit set to 470mA.
device shuts down all outputs and asserts FAULT.
INPUT
t
t
t
DBC
DBC
DBC
DEBOUNCED
OUTPUT
Figure 5. INPUT and OUTPUT Debounced Feature
______________________________________________________________________________________ 17
Single PCI Express, Hot-Plug
Controller
SHUT DOWN
12V AND 3.3V OUTPUTS.
ASSERT FAULT
WAS CURRENT
LIMIT DETECTED ON ANY
12V OR
Y
12V AND 3.3V
OUTPUTS
ARE ENABLED
Y
HAS t
ELAPSED?
FAULT
START COUNTING
t
FAULT
STAY WAITING FOR
3.3V OUTPUT?
t
RESTART
N
N
IS FAULT STILL
PRESENT?
Y
N
RESET t
FAULT
COUNTER
Y
N
LATCH-OFF
OPTION?
RESET FAULT
AND
RESTART 12V, 3.3V
SUPPLIES
STAY WAITING FOR
ON_ TRANSITION
HIGH->LOW->HIGH
N
POWER-ON MAIN
SUPPLIES FAULT
AND PWRGD ARE
HIGH IMPEDANCE
ENABLE CHARGE ON
12G AND 3.3G
PINS. START
Y
3.3AUXIN IS ON
AND ABOVE UVLO
HAS t
ELAPSED?
SU
COUNTING t
SU
RESET
PWRGD
POR_LH
ARE PWRGD
THRESHOLDS
REACHED?
N
AFTER t
DELAY
Y
STAY WAITING FOR BOTH
ON AND AUXON
TRANSITION
HIGH->LOW->HIGH
RESET FAULT
AND
RESTART ALL SUPPLIES
ASSERT
PWRGD
AFTER t
DELAY
POR_HL
N
Y
POWER-ON AUXILIARY
ENABLE CHARGE ON
Y
SUPPLIES FAULT
AND PWRGD ARE
HIGH IMPEDANCE
INTERNAL AUXILIARY
MOSFET, BEGIN
HAS t ELAPSED?
SU
N
COUNTING t
LATCH-OFF
OPTION?
SU
SHUT DOWN
ALL OUTPUTS,
ASSERT FAULT,
STAY WAITING FOR
Y
Y
WAS CURRENT LIMIT
DETECTED ON AUXILIARY
OUTPUT?
IS t
ELAPSED?
START COUNTING
FAULT
AUX SUPPLY OUTPUT
IS ENABLED
t
FAULT
t
ELAPSED.
RESTART
N
N
Y
IS FAULT STILL
PRESENT?
N
RESET t
FAULT
COUNTER
Figure 6. Fault Management Flow Chart
18 ______________________________________________________________________________________
Single PCI Express, Hot-Plug
Controller
Maximum and minimum values for R
are 500kΩ
PORADJ
Applications Information
and 500Ω, respectively. Leave PORADJ floating for a
Setting the Fault Timeout Period (t
)
default t of 160ms.
FAULT
POR
t
is the time an overcurrent or overtemperature
FAULT
Component Selection
fault must remain for the MAX5954 to disable the main
or auxiliary outputs. Program the fault timeout period
Select the external n-channel MOSFET according to the
applications current requirement. Limit the switch
power dissipation by choosing a MOSFET with an
(t
) by connecting a resistor (R ) from TIM to GND.
TIM
can be calculated by the following equation:
FAULT
t
FAULT
R
low enough to have a minimum voltage drop at
DS_ON
full load. High R
t
= 166ns / Ω x R
causes larger output ripple if
DS_ON
FAULT
TIM
there are pulsed loads. High R
can also trigger an
DS_ON
The t
programmed time duration must be chosen
FAULT
external undervoltage fault at full load. Determine the
MOSFET’s power rating requirement to accommodate a
short-circuit condition on the board during startup. Table
3 lists MOSFETs and sense-resistor manufacturers.
according to the total capacitance load connected to
12G and 3.3G. To properly power-up the main supply
outputs, the following constraints need to be taken:
V
× C
LOAD
GATE
Additional External Gate Capacitance
External capacitance can be added from the gate of
the external MOSFETs to GND to slow down the dV/dt
of the 12V and 3.3V outputs.
t
≥
SU
I
CHG
where t = 2 x t
and where:
SU
FAULT
1) I
= 5µA.
CHG
Maximum Load Capacitance
Large capacitive loads at the 12V output, the 3.3V out-
put, and the 3.3V auxiliary output can cause a problem
when inserting discharged PCI cards into live back-
planes. A fault occurs if the time needed to charge the
capacitance of the board is greater than the typical
2) V
3) C
= 18.4V for 12G and V
= 9.4V for 3.3G.
GATE
LOAD
GATE
is the total capacitance load at the gate.
are 500kΩ and
Maximum and minimum values for R
TIM
500Ω, respectively. Leave TIM floating for a default
t
of 11ms.
FAULT
startup time (2 x t
). The MAX5954 can withstand
FAULT
Setting the Power-On-Reset
Timeout Period (t
large capacitive loads due to their adjustable startup
times and adjustable current-limit thresholds. Calculate
the maximum load capacitance as follows:
)
POR_HL
t
is the time from when the gate voltages of all
POR_HL
outputs reach their power-good threshold to when
t
× I
SU LIM
V
PWRGD pulls low. Program the power-on-reset timeout
C
<
LOAD
period (t
PORADJ to GND. t
lowing equation:
) by connecting a resistor (R
) from
PORADJ
can be calculated by the fol-
OUT
POR
POR_HL
V
is either the 3.3V output, the 12V output, or the
OUT
3.3V auxiliary output.
t
= 2.5µs / Ω x R
PORADJ
POR_HL
Table 3. Component Manufacturers
COMPONENT
MANUFACTURER
PHONE
402-564-3131
704-264-8861
888-522-5372
310-322-3331
602-244-3576
—
WEBSITE
www.vishay.com
Vishay-Dale
IRC
Sense Resistor
www.irctt.com
Fairchild
www.fairchildsemi.com
www.irf.com
International Rectifier
Motorola
MOSFETs
www.mot-sps.com/ppd/
www.vishay.com
Vishay-Siliconix
______________________________________________________________________________________ 19
Single PCI Express, Hot-Plug
Controller
Input Transients
Chip Information
The 12V input (12VIN), the 3.3V input (3.3S+), and the
PROCESS: BiCMOS
3.3V auxiliary (3.3VAUXIN) must be above their UVLO
thresholds before startup can occur. Input transients
can cause the input voltage to sag below the UVLO
threshold. The MAX5454 rejects transients on the input
supplies that are shorter than 4µs (typ).
20 ______________________________________________________________________________________
Single PCI Express, Hot-Plug
Controller
Typical Application Circuit
V
12VIN
ADD-IN
CARD
PCI EXPRESS
SLOT
1µF
Q1
IN5819
V
PRSNT1#
3.3AUXIN
R1
8mΩ
SI7448DP-T1
+12V
GND
0.1µF
PWRGD
PWRGD#
3.3VAUX
R
TIM = OPEN
10kΩ
TIM
MAX5954
3.3VAUX0
R
PORADJ = OPEN
PGND
GND
PORADJ
R2
5mΩ
Q2
SI7448DP-T1
V
+3.3V
3.3VIN
0.1µF
V
3.3AUXIN
10kΩ
PRSNT2#
MRL
MAX7311
16-BIT I/O EXPANDER
LEDs
2
2
3
SMBUS
AO-2
INT
______________________________________________________________________________________ 21
Single PCI Express, Hot-Plug
Controller
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
(NE-1) X
e
E
E/2
k
D/2
C
(ND-1) X
e
D
D2
L
D2/2
e
b
E2/2
L
C
L
k
E2
e
L
C
C
L
L
L1
L
L
e
e
A
A1
A2
PACKAGE OUTLINE
36, 40, 48L THIN QFN, 6x6x0.8mm
1
F
21-0141
2
NOTES:
1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994.
2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES.
3. N IS THE TOTAL NUMBER OF TERMINALS.
4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1
SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE
ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE.
5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.25 mm AND 0.30 mm
FROM TERMINAL TIP.
6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY.
7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION.
8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS.
9. DRAWING CONFORMS TO JEDEC MO220, EXCEPT FOR 0.4mm LEAD PITCH PACKAGE T4866-1.
10. WARPAGE SHALL NOT EXCEED 0.10 mm.
11. MARKING IS FOR PACKAGE ORIENTATION REFERENCE ONLY.
12. NUMBER OF LEADS SHOWN FOR REFERENCE ONLY.
PACKAGE OUTLINE
36, 40, 48L THIN QFN, 6x6x0.8mm
2
F
21-0141
2
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
22 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2006 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products, Inc.
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