General Description
The MAX5934/MAX5934A are fully integrated hot-swap
controllers for +9V to +80V (MAX5934A) positive supply
rails. The MAX5934 is optimized for +33V to +80V
power-supply rails. These devices allow for the safe
insertion and removal of circuit cards into a live back-
plane without causing glitches on the backplane
power-supply rail. The MAX5934/MAX5934A feature a
programmable analog foldback current limit, program-
mable undervoltage lockout, and programmable out-
put-voltage slew rate through an external n-channel
MOSFET. In addition, if these devices remain in current
limit for more than a programmable time, the external
n-channel MOSFET latches off.
The MAX5934/MAX5934A feature pin-selectable
PWRGD_ assertion polarity (active low or active high)
and pin-selectable fault management (latched or
autoretry). Other features include automatic restart after
a circuit-breaker fault, selectable duty-cycle (DC)
options, and thermal-shutdown mode for overtempera-
ture protection.
The MAX5934/MAX5934A operate in the extended
(-40°C to +85°C) temperature range and are available
in a 16-pin QSOP package.
Applications
Hot Board Insertion
Electronic Circuit Breakers
Industrial High-Side Switch/Circuit Breakers
Network Routers and Switches
24V/48V Industrial/Alarm Systems
Features
♦Provides Safe Hot Swap for +9V to +80V Power
Supplies (MAX5934A)
♦Safe Board Insertion and Removal from a Live
Backplane
♦Pin-Selectable Active-Low or Active-High Power-
Good Output
♦Pin-Selectable Latched or Autoretry Fault
Management
♦Programmable Foldback Current Limiting
♦High-Side Drive for an External N-Channel MOSFET
♦Built-In Thermal Shutdown
♦Undervoltage Lockout (UVLO)
♦Pin-Selectable Duty-Cycle Options (0.94%, 1.88%,
3.75%)
MAX5934/MAX5934A
Positive High-Voltage, Hot-Swap Controllers with
Selectable Fault Management and Status Polarity
________________________________________________________________ Maxim Integrated Products 1
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
LATCH/RETRY VCC
DC
SENSE
N.C.
FB2
GATE
TIMER
OUT
TOP VIEW
MAX5934
MAX5934A
QSOP
ON
POL_SEL
PWRGD1
FB1
PWRGD2
PWRGD3
GND
Pin Configuration
Ordering Information
PART DEFAULT UVLO
(V)
SUPPLY VOLTAGE
RANGE (V)
LATCHED/
AUTORETRY FAULT
PROTECTION
DUTY CYCLE PWRGD_
OUTPUT LOGIC
MAX5934 31 +33 to +80 Pin-selectable Pin-selectable Pin-selectable
MAX5934A 8.3 +9 to +80 Pin-selectable Pin-selectable Pin-selectable
Selector Guide
19-3282; Rev 1; 7/04
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.
Typical Application Circuit appears at end of data sheet.
PART TEMP RANGE PIN-PACKAGE
MAX5934EEE -40°C to +85°C 16 QSOP
MAX5934AEEE -40°C to +85°C 16 QSOP
MAX5934/MAX5934A
Positive High-Voltage, Hot-Swap Controllers with
Selectable Fault Management and Status Polarity
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC = +24V (MAX5934A), VCC = +48V (MAX5934), GND = 0V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at
TA= +25°C.) (Note 1)
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.
(Voltages referenced to GND.)
VCC .........................................................................-0.3V to +85V
SENSE, FB_, ON.........................................-0.3V to (VCC + 0.3V)
TIMER, PWRGD_, DC, LATCH/RETRY, POL_SEL ....-0.3V to +85V
GATE ......................................................................-0.3V to +95V
OUT ................................................(VGATE - 14V) to the lower of
(VGATE + 0.3V) and (VCC + 0.3V)
Maximum GATE Current ....................................-50mA, +150mA
Maximum Current into Any Other Pin................................±50mA
Continuous Power Dissipation (TA= +70°C)
16-Pin QSOP (derate 8.3mW/°C above +70°C)...........667mW
Operating Temperature Range ...........................-40°C to +85°C
Maximum Junction Temperature .....................................+150°C
Storage Temperature Range .............................-60°C to +150°C
ESD Rating (Human Body Model)......................................2000V
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX5934A 9 80
Supply Voltage Range VCC MAX5934 33 80 V
Supply Current ICC VON = 3V, VCC = 80V 1.4 3.5 mA
MAX5934A 7.5 8.3 8.8
VCC Undervoltage Lockout VLKO VCC low-to-high
transition MAX5934 29.5 31 32.5 V
MAX5934A 0.4
VCC Undervoltage-Lockout
Hysteresis VLKOHYST MAX5934 2 V
FB1 High-Voltage Threshold VFB1H FB1 low-to-high transition 1.280 1.313 1.345 V
FB2 High-Voltage Threshold VFB2H FB2 low-to-high transition 1.280 1.313 1.345 V
FB1 Low-Voltage Threshold VFB1L FB1 high-to-low transition 1.221 1.233 1.245 V
FB2 Low-Voltage Threshold VFB2L FB2 high-to-low transition 1.202 1.264 V
FB_ Hysteresis VFBHYST 80 mV
FB_ Input Bias Current IINFB VFB_ = 0V -1 +1 µA
FB1 Threshold Line Regulation ∆VFB1 VCC(MIN) ≤ VCC ≤ 80V, MAX5934A,
ON = 0V 0.05 mV/V
FB2 Threshold Line Regulation ∆VFB2 VCC(MIN) ≤ VCC ≤ 80V, MAX5934A,
ON = 0V 0.05 mV/V
VFB_ = 0V, TA = 0°C to +70°C 8 12 17
SENSE Trip Voltage
(VCC - VSENSE)VSENSETRIP VFB_ = 1V, TA = 0°C to +70°C394755
mV
GATE Pullup Current IGATEUP Charge pump on, VGATE = 7V -5 -10 -20 µA
GATE Pulldown Current IGATEDN Any fault condition, VGATE = 2V 35 70 100 mA
(VGATE - VCC) at PWRGD3
Assertion ∆V
GAT E P WRGD 3VGATE - VCC, low-to-high transition 3.8 4.3 5 V
VGATE - VCC, MAX5934 10 13.6 18
VCC = 10.8V to 20V 4.5 13.6 18.0External N-Channel Gate Drive ∆VGATE VGATE - VCC,
MAX5934A VCC = 20V to 80V 10 13.6 18
V
TIMER Pullup Current ITIMERUP VTIMER = 0V -24 -75 -120 µA
MAX5934/MAX5934A
Positive High-Voltage, Hot-Swap Controllers with
Selectable Fault Management and Status Polarity
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +24V (MAX5934A), VCC = +48V (MAX5934), GND = 0V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at
TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
DC = 3.75%, DC = floating 1.5 3 4.5
DC = 1.88%, DC = high 0.75 1.5 2.25
TIMER Pulldown Current ITIMERON VTIMER = 1V
DC = 0.94%, DC = low 0.37 0.75 1.12
µA
ON High Threshold VONH ON low-to-high transition 1.280 1.313 1.355 V
ON Low Threshold VONL ON high-to-low transition 1.221 1.233 1.245 V
ON Hysteresis VONHYST 80 mV
ON Input Bias Current IINON VON = 0V -1 +1 µA
LATCH/RETRY and POL_SEL
Low-Voltage Threshold
VLRIL,
VPOS_SEL_IL 0.4 V
LATCH/RETRY and POL_SEL
High-Voltage Threshold
VLRIH,
VPOS_SEL_IH 3.2 V
VPOL_SEL = 80V 4.5
LATCH/RETRY and POL_SEL
Input Current
ILR_IN,
IPOS_SEL_IN VPOL_SEL = 0V -37 µA
Source GATE Clamp Voltage VSGZ VGATE - VOUT 15 16.4 19 V
IO = 2mA 0.4
PWRGD_ Output Low Voltage VOL IO = 4mA 2.5 V
PWRGD_ Leakage Current IOH VPWRGD_ = 80V 10 µA
Thermal Shutdown Temperature rising +150 °C
Thermal-Shutdown Hysteresis 20 °C
SENSE Input Bias Current ISENSE VSENSE = 0 to VCC -1 +3 µA
DC High-Voltage Threshold 1 VDCHTH Ri si ng ed g e, D C tr ansi ti on fr om 3.75% to
1.88% 2.150 2.600 2.850 V
DC High-Voltage Threshold 2 VDCLTH Ri si ng ed g e, D C tr ansi ti on fr om 0.94% to
3.75% 1.075 1.250 1.425 V
DC High-Voltage Threshold 1
Hysteresis VDCLHYS 45 mV
DC High-Voltage Threshold 2
Hysteresis VDCLHYS 45 mV
DC Input Open-Circuit Voltage VDCOC 1.9 V
DC Input Impedance RDC_IN 57 kΩ
V_DC = 80V 50
DC Input Current IDC_IN V_DC = 0V -34 µA
ON Low-to-GATE Low
Propagation Delay tPHLON CGATE = 0, Figures 1 and 2 6 µs
ON High-to-GATE High
Propagation Delay tPLHON CGATE = 0, Figures 1 and 2 1.7 µs
MAX5934/MAX5934A
Positive High-Voltage, Hot-Swap Controllers with
Selectable Fault Management and Status Polarity
4 _______________________________________________________________________________________
Test Circuit and Timing Diagrams
MAX5934
MAX5934A
ON
LATCH/
RETRY
VCC
OUT
DC
SENSE
FB2
GATE
TIMER
POL_SEL
FB1
PWRGD2
PWRGD1
PWRGD3
GND N.C.
5kΩ5V
5kΩ5V
5kΩ5V
Figure 1. Test Circuit
ON
GATE
1.313V 1.233V
5V 1V
tPHLON
tPLHON
Figure 2. ON-to-GATE Timing
FB
PWRGD
1.313V
1V
1.233V
1V
tPLHFB tPHLFB
Figure 3. FB_-to-PWRGD_ Timing
VCC - SENSE
GATE
47mV
VCC
tPHLSENSE
Figure 4. SENSE-to-GATE Timing
Note 1: All currents into the device are positive and all currents out of the device are negative. All voltages are referenced to
ground, unless noted otherwise.
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +24V (MAX5934A), VCC = +48V (MAX5934), GND = 0V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at
TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
FB_ Low-to-PWRGD_ Low
Propagation Delay tPHLFB_ Figures 1, 3 3.2 µs
FB_ High-to-PWRGD_ High
Propagation Delay tPLHFB_ Figures 1, 3 1.5 µs
(VCC - VSENSE) High-to-GATE
Low Propagation Delay tPHLSENSE TA = +25°C, CGATE = 0, Figures 1 and 4 0.5 1.8 2.5 µs
MAX5934/MAX5934A
Positive High-Voltage, Hot-Swap Controllers with
Selectable Fault Management and Status Polarity
_______________________________________________________________________________________ 5
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5934 toc01
VCC (V)
ICC (mA)
7256 644840
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2.7
0
33 80
TA = +85°CTA = +25°C
TA = -40°C
SUPPLY CURRENT vs. TEMPERATURE
MAX5934 toc02
TEMPERATURE (°C)
ICC (mA)
603510-15
0.5
1.0
1.5
2.0
2.5
3.0
0
-40 85
VCC = 48V
VCC = 33V
FB_ LOW-VOLTAGE THRESHOLD
vs. TEMPERATURE
MAX5934 toc03
TEMPERATURE (°C)
FB_ LOW-VOLTAGE THRESHOLD (V)
603510-15
1.205
1.215
1.225
1.235
1.245
1.210
1.220
1.230
1.240
1.250
1.200
-40 85
FB_ HIGH-VOLTAGE THRESHOLD
vs. TEMPERATURE
MAX5934 toc04
TEMPERATURE (°C)
FB_ HIGH-VOLTAGE THRESHOLD (V)
603510-15
1.285
1.295
1.305
1.320
1.330
1.290
1.300
1.315
1.310
1.325
1.335
1.280
-40 85
FB_ HYSTERESIS vs. TEMPERATURE
MAX5934 toc05
TEMPERATURE (°C)
FB_ HYSTERESIS (V)
603510-15
0.05
0.06
0.07
0.08
0.09
0.10
0.11
0.04
-40 85
IGATE PULLUP CURRENT
vs. TEMPERATURE
MAX5934 toc06
TEMPERATURE (°C)
IGATE PULLUP CURRENT (µA)
603510-15
-10
-11
-12
-9
-8
-7
-6
-5
-13
-40 85
GATE DRIVE vs. SUPPLY VOLTAGE
MAX5934 toc08
VCC (V)
GATE DRIVE (VGATE - VCC) (V)
7264564840
11
12
13
14
15
16
17
10
32 80
GATE DRIVE
vs. TEMPERATURE
MAX5934 toc07
TEMPERATURE (°C)
GATE DRIVE (VGATE - VCC) (V)
603510-15
10
9
8
11
12
14
16
13
15
17
7
-40 85
VCC = +48V
VCC = +33V
Typical Operating Characteristics
(VCC = +48V, TA= +25°C, unless otherwise noted.)
MAX5934/MAX5934A
Positive High-Voltage, Hot-Swap Controllers with
Selectable Fault Management and Status Polarity
6 _______________________________________________________________________________________
TIMER PULLUP CURRENT
vs. TEMPERATURE
MAX5934 toc09
TEMPERATURE (°C)
TIMER PULLUP CURRENT (µA)
603510-15
-85
-80
-75
-70
-65
-60
-90
-40 85
TIMER PULLUP CURRENT
vs. SUPPLY VOLTAGE
MAX5934 toc10
VCC (V)
TIMER PULLUP CURRENT (µA)
7264564840
-78
-77
-76
-75
-74
-73
-79
33 80
TA = +85°C
TA = +25°C
TA = -40°C
ON HIGH-VOLTAGE THRESHOLD
vs. TEMPERATURE
MAX5934 toc11
TEMPERATURE (°C)
ON HIGH-VOLTAGE THRESHOLD (V)
603510-15
1.293
1.303
1.313
1.323
1.333
1.343
1.283
-40 85
ON LOW-VOLTAGE THRESHOLD
vs. TEMPERATURE
MAX5934 toc12
TEMPERATURE (°C)
ON LOW-VOLTAGE THRESHOLD (V)
603510-15
1.215
1.225
1.235
1.245
1.255
1.265
1.205
-40 85
ON HYSTERESIS
vs. TEMPERATURE
MAX5934 toc13
TEMPERATURE (°C)
ON HYSTERESIS (V)
603510-15
0.072
0.074
0.076
0.078
0.080
0.070
-40 85
VCC = +48V
PWRGD_ OUTPUT VOLTAGE LOW
vs. LOAD CURRENT
MAX5934 toc14
ILOAD (mA)
PWRGD_ VOUT LOW (V)
705030
2
4
6
8
10
12
14
16
18
20
0
10 90
TA = +85°CTA = +25°CTA = -40°C
Typical Operating Characteristics (continued)
(VCC = +48V, TA= +25°C, unless otherwise noted.)
SENSE REGULATION VOLTAGE
vs. FB_ VOLTAGE
MAX5934 toc15
VFB (V)
SENSE REGULATION VOLTAGE (mV)
0.80.60.2 0.4
5
10
15
20
25
30
35
40
45
50
0
01.0
MAX5934/MAX5934A
Positive High-Voltage, Hot-Swap Controllers with
Selectable Fault Management and Status Polarity
_______________________________________________________________________________________ 7
Pin Description
PIN NAME FUNCTION
1LATCH/
RETRY
Circuit-Breaker Fault-Management Select Input. Connect LATCH/RETRY to GND to latch off after a circuit-
breaker fault. Leave LATCH/RETRY open or drive to logic-high voltage for automatic restart after a circuit-
breaker fault.
2ON
On/Off Control Input. ON implements the undervoltage-lockout threshold and resets the part after a fault
latch (see the Fault Management (
LATCH
/RETRY) section).
3 POL_SEL PWRGD_ Polarity Select Input. Leave POL_SEL open or drive to logic-high voltage for PWRGD_ asserted
high. Connect POL_SEL to GND for PWRGD_ asserted low.
4 FB1
Power-Good Comparator Input. Connect a resistive divider between output, FB1, and GND to monitor the
output voltage (see the Power-Good (PWRGD_ ) Detection section). FB1 is also used as feedback for the
current-limit foldback function.
5 PWRGD2
Open-Drain Power-Good Output. POL_SEL determines the output polarity of PWRGD2. PWRGD2 is
asserted when FB2 is higher than VFB2H. PWRGD2 deasserts when FB2 is lower than VFB2L (see the
Power-Good (PWRGD_) Detection section).
6 PWRGD1
Open-Drain Power-Good Output. POL_SEL determines the output polarity of PWRGD1. PWRGD1 is
asserted when FB1 is higher than VFB1H. PWRGD1 deasserts when FB1 is lower than VFB1L (see the
Power-Good (PWRGD_) Detection section).
7 PWRGD3
Open-Drain Power-Good Output. POL_SEL determines the output polarity of PWRGD3. PWRGD3 asserts
when GATE is at maximum voltage. PWRGD3 deasserts after the timeout following an overcurrent event
(see the Power-Good (PWRGD_) Detection section).
8 GND Ground
9 OUT Output Voltage. OUT is used as the return path for the internal GATE protection clamping circuitry.
10 TIMER Timing Input. Connect a capacitor from TIMER to GND to program the maximum time the part is allowed to
remain in current limit (see the TIMER section).
11 GATE Gate-Drive Output. The high-side gate drive for the external n-channel MOSFET (see the GATE section).
12 FB2 Noninverting Comparator Input. FB2 is used to monitor any other voltage in the system. When FB2 rises
higher than VFB2H, PWRGD2 asserts. When FB2 drops below VFB2L, PWRGD2 deasserts.
13 N.C. No Connection. Not internally connected.
14 SENSE Current-Sense Input. Connect a sense resistor from VCC to SENSE and the drain of the external n-channel
MOSFET.
15 DC Duty-Cycle Select. When DC is floating, the default duty cycle is 3.75%. Connect DC to VCC to set the duty
cycle to 1.88%. Connect DC to GND to set the duty cycle to 0.94%.
16 VCC Power-Supply Input. Bypass VCC to GND with a 0.1µF capacitor. The input voltage range is from +9V to
+80V for the MAX5934A and +33V to +80V for the MAX5934.
MAX5934/MAX5934A
Positive High-Voltage, Hot-Swap Controllers with
Selectable Fault Management and Status Polarity
8 _______________________________________________________________________________________
Functional Diagram
MAX5934
MAX5934A
VP GEN
VP OPEN
DRAIN
OPEN
DRAIN
OPEN
DRAIN
1.233V
1.233V
4.3V
SENSE
VCC
FB1
PWRGD3
GATE
OUT
FB2
PWRGD1
ON
PWRGD2
POL_SEL
LATCH/RETRY
DC
TIMER
GATE
CHARGE
PUMP
AND
GATE
DRIVER
REF
GEN
VCC
VUVLO
0.5V
VP
75µA
ITIMERON
GND
LOGIC
PWRGD_
POLARITY
SELECT
CIRCUIT-
BREAKER FAULT-
MANAGEMENT
SELECT
DUTY
CYCLE
MAX5934/MAX5934A
Positive High-Voltage, Hot-Swap Controllers with
Selectable Fault Management and Status Polarity
_______________________________________________________________________________________ 9
Detailed Description
The MAX5934/MAX5934A are fully integrated hot-swap
controllers for positive supply rails. These devices allow
for the safe insertion and removal of circuit cards into
live backplanes without causing glitches on the back-
plane power-supply rail. During startup, the MAX5934/
MAX5934A act as current regulators using an external
sense resistor and MOSFET to limit the amount of cur-
rent drawn by the load.
The MAX5934A operates from a +9V to +80V supply
voltage range and has a default UVLO set to +8.3V.
The MAX5934 operates from a +33V to +80V supply
voltage range and has a default UVLO set to +31V. The
UVLO threshold is adjustable using a resistive divider
connected from VCC to ON to GND (see R2 and R3 in
Figure 5).
The MAX5934/MAX5934A monitor input voltage, output
voltage, output current, and die temperature. These
devices feature three power-good outputs (PWRGD_)
to indicate status by monitoring the voltage at FB1,
FB2, and GATE (see the Power-Good (PWRGD_)
Detection section). PWRGD1 indicates an output-volt-
age status, PWRGD2 can be used to indicate an over-
voltage condition on the main power-supply rail, and
PWRGD3 asserts when GATE voltage has charged to
4.3V above the supply rail. PWRGD3 deasserts when
the TIMER voltage exceeds a 1.233V threshold in
response to an extended fault condition.
The MAX5934/MAX5934A control gate voltage on the
external MOSFET to limit load current at startup and at
overload to a value determined as:
MAX5934
MAX5934A
ON
CL
OUT
GATESENSE
VCC
16 14 11
9
4
6
5
7
12
8
M1
R1
1kΩ, 5%
RSENSE
0.025Ω
C1
10nF
RG
10Ω
5%
R4
59kΩ
1%
R6
24kΩ
5%
R7
24kΩ
5%
R10
1kΩ
1%
R9
90kΩ
1%
R2
49.9kΩ
1%
VIN
R3
3.4kΩ
1%
CTIMER
0.68µF
RL
R5
3.57kΩ
1%
FB1
2
10
1
3
15
PWRGD1
PWRGD2
TIMER
LATCH/RETRY
VCC
FB2
PWRGD3
VMONITOR
PWRGD1
PWRGD2
PWRGD3
DC
GND
VCC
POL_SEL
VCC
IRF530
Figure 5. Application Circuit
MAX5934/MAX5934A
Positive High-Voltage, Hot-Swap Controllers with
Selectable Fault Management and Status Polarity
10 ______________________________________________________________________________________
where:
VSENSETRIP = VIN - VSENSE
VSENSETRIP varies from a low of 12mV when the voltage
at FB1 = 0V and increases to 47mV as the voltage at
FB1 increases to 0.5V and beyond (see Figure 6).
Thus, the current limit is low at a low output voltage,
and increases as the output voltage reaches its final
value. This gradually increases the limiting load current
at startup and creates a foldback current limit under
overload or short-circuit conditions. See Figure 5 for
FB1 and RSENSE connections.
Power-Up Mode
During power-up, the MAX5934/MAX5934A gradually
turn on the external n-channel MOSFETs. The
MAX5934/MAX5934A monitor and provide current-limit
protection to the load at all times. The current limit is
programmable using an external current-sense resistor
connected from VCC to SENSE. The MAX5934/
MAX5934A feature current-limit foldback and duty-cycle
limit to ensure robust operation during load-fault and
short-circuit conditions (see the Detailed Description
and Overcurrent Protection sections).
TIMER
Connect an external capacitor from TIMER to ground to
set the maximum overcurrent timeout limit. When the volt-
age at TIMER reaches 1.233V, GATE goes low and the
75µA pullup current turns off (see the Functional
Diagram). As a result, a preset pulldown current
(ITIMERON) discharges the capacitor. To reset the internal
fault latch, these two conditions must be met:
1) TIMER’s voltage goes below 0.5V
2) ON goes low
When the current limit is not active, TIMER goes low by
the ITIMERON current source. After the current limit
becomes active, the ITIMEROFF pullup current source is
connected to TIMER and the voltage rises with a slope
of 75µA/CTIMER as long as the current limit remains
active. A capacitor from TIMER to GND (CTIMER) sets
the desired current-limit timeout:
TLIMIT = (CTIMER / 75µA) x 1.233V
GATE
GATE provides a high-side gate drive for the external
n-channel MOSFET. An internal charge-pump circuit
guarantees at least 10V of gate drive for supply voltages
higher than 20V (MAX5934A) and a 4.5V gate drive for
supply voltages between 10.8V and 20V (MAX5934A)
(for the MAX5934, see the Electrical Characteristics
table). Connect an external capacitor from GATE to
ground to set the rising slope of the voltage at GATE.
The voltage at GATE is adjusted to maintain a constant
voltage across RSENSE when the current limit is reached
while the TIMER capacitor starts to charge. When the
voltage at TIMER exceeds 1.233V, the voltage at GATE
goes low.
The MAX5934/MAX5934A monitor voltages at ON, VCC,
and TIMER. GATE is pulled to GND whenever ON goes
low, or the VCC supply voltage decreases below the
UVLO threshold, or TIMER increases above the 1.233V
threshold.
Gate Voltage
The Gate Drive vs. Supply Voltage graph in the Typical
Operating Characteristics illustrates that GATE clamps
to a maximum of 18V above the input voltage. The
MAX5934 minimum gate-drive voltage is 10V at a mini-
mum input-supply voltage of 33V. The MAX5934A mini-
mum gate-drive voltage is 4.5V at a minimum supply of
10.8V. Therefore, a logic-level MOSFET must be used if
the input supply is below 20V.
Fault Management (
LATCH
/RETRY)
The MAX5934/MAX5934A feature either latched-off or
autoretry fault management configurable by the
LATCH/RETRY input. To select automatic restart after a
circuit-breaker fault, drive LATCH/RETRY high (above
VLRIH) or leave it floating (see Figure 5).
IV
R
LOAD SENSETRIP
SENSE
=
0.5V0V
12mV
47mV
VCC - VSENSE
VFB
Figure 6. Current-Limit Sense Voltage vs. Feedback Voltage
MAX5934/MAX5934A
Positive High-Voltage, Hot-Swap Controllers with
Selectable Fault Management and Status Polarity
______________________________________________________________________________________ 11
In latch mode, the MAX5934/MAX5934A turn the
MOSFET off and keep it off after an overcurrent fault.
After the fault condition goes away and TIMER falls
below 0.5V, recycle the power supplies or toggle ON
low and high again to unlatch the device.
In autoretry mode, the MAX5934/MAX5934A turn the
MOSFET off after an overcurrent fault occurs. After the
fault condition is removed, the device waits for TIMER to
fall below 0.5V and then automatically restarts. If the fault
is due to an overtemperature condition, the MAX5934/
MAX5934A wait for the die temperature to cool down
below the +130°C threshold before restarting.
Power-Good (PWRGD_ ) Detection
The MAX5934/MAX5934A feature three power-good
outputs (PWRGD_) to indicate the status of three sepa-
rate voltages. PWRGD_ asserts if the device detects an
error condition.
PWRGD_ is true when FB_ voltages exceed the low-to-
high threshold voltage (VFB_H). PWRGD_ is false when
FB_ voltages go lower than the high-to-low threshold
voltage (VFB_L).
Connect external pullup resistors between PWRGD_
and OUT to pull up the PWRGD_ voltages to VOUT.
PWRGD2 can be used to indicate an overvoltage con-
dition on the main power-supply rail.
PWRGD3 asserts when GATE voltage has charged to
4.3V above the supply rail. PWRGD3 deasserts when
the TIMER voltage exceeds 1.233V threshold in response
to an extended fault condition.
The output polarity of PWRGD_ is determined by
POL_SEL. Drive POL_SEL high or leave it floating to
select PWRGD_ active high. Connect POL_SEL to GND
for PWRGD_ active low.
Undervoltage Lockout (UVLO)
The MAX5934A operates from a +9V to +80V supply
voltage range and has a default UVLO set at +8.3V.
The MAX5934 operates from a +33V to +80V supply
voltage range and has a default UVLO set at +31V. The
UVLO thresholds are adjustable using a resistive
divider connected to VCC (see R2 and R3 in Figure 5).
When the input voltage (or VCC) is below the UVLO
threshold, the MOSFET is held off. When the input volt-
age (or VCC) is above the UVLO threshold, the
MAX5934/MAX5934A go into normal operation (or
begin to turn on the external MOSFET).
To adjust the UVLO threshold, connect an external
resistive divider from VIN (or VCC) to ON and then from
ON to GND. The following equation is used to calculate
the new UVLO threshold:
VUVLO_TH = VREF (1 + (R2 / R3))
where VREF is typically 1.233V.
Applications Information
Hot-Circuit Insertion
The supply bypass capacitors on a circuit board can
draw high peak currents from the backplane power bus
as they charge when the circuit boards are inserted
into a live backplane. This can cause permanent dam-
age to the connector pins and glitch the system supply
causing other boards in the system to reset.
The MAX5934/MAX5934A are capable of controlling a
board’s power-supply voltage allowing for the safe
insertion or removal of a board from a live backplane.
These devices provide undervoltage and overcurrent
protection and power-good output signals (PWRGD_).
Overcurrent Protection
The MAX5934/MAX5934A provide sophisticated overcur-
rent protection to ensure robust operation under output-
current-transient and overcurrent fault conditions. The
current-protection circuit employs a foldback current limit
and a short-circuit or excessive output-current protection.
The MAX5934/MAX5934A offer a current foldback fea-
ture where the current folds back as a function of the
output voltage that is sensed at FB1. As Figure 6 illus-
trates, the voltage across RSENSE decreases linearly
when FB1 drops below 0.5V and stops at 12mV when
VFB1 = 0V. The maximum current-limit equation is:
ILIMIT = 47mV / RSENSE
For RSENSE = 0.025Ω, the current limit is set to 1.88A
and goes down to 480mA at short circuit (output short-
ed to GND).
In addition, the MAX5934/MAX5934A feature an
adjustable overcurrent response time. The required
time to regulate the MOSFET current depends on the
input capacitance of the MOSFET, GATE capacitor
(C1), compensation resistor (R1), and the internal delay
from SENSE to GATE. Figure 7 shows the propagation
delay from a voltage step at SENSE until GATE starts to
fall, as a function of overdrive.
MAX5934/MAX5934A
Positive High-Voltage, Hot-Swap Controllers with
Selectable Fault Management and Status Polarity
12 ______________________________________________________________________________________
Undervoltage and Overvoltage Detection
An undervoltage fault is detected when VON goes
below the trip point (VONL = 1.233V). When this occurs,
GATE pulls low and stays low until VON rises above
(VONH = 1.313V).
An example of overvoltage protection is shown in
Figure 8. Zener diode D1 turns on when VIN exceeds
the diode’s breakdown voltage and begins to pull
TIMER high. When VTIMER goes higher than 1.233V, a
fault is detected and GATE pulls low. As a result, Q1
turns off. Figure 9 shows overvoltage waveforms for VIN
(see the Fault Management (
LATCH
/RETRY) section for
restart conditions).
Supply Transient Protection
The MAX5934/MAX5934A are guaranteed to be safe
from damage with supply voltages of up to 85V. Spikes
at voltages above 85V may damage the part.
Instantaneous short-circuit conditions, can cause large
RESPONSE TIME TO OVERCURRENT
VCC - VSENSE (mV)
PROPAGATION DELAY (µs)
200100
2
4
6
8
10
12
14
0
0 300
50 150 250
Figure 7. Response Time to Overcurrent
MAX5934
MAX5934A
ON
CL
OUT
GATESENSE
VCC
16 14 11
9
4
6
5
7
12
8
M1
R1
1kΩ
5%
RSENSE
0.025Ω
C1
10nF
R4
59kΩ
1%
R6
24kΩ
5%
R7
24kΩ
5%
R8
24kΩ
5%
R10
1kΩ
1%
R9
90kΩ
1%
VIN
RG
10Ω
5%
CTIMER
0.68µF
R5
3.57kΩ
1%
FB1
2
10
1
3
15
PWRGD1
PWRGD2
TIMER
LATCH/RETRY
VCC
FB2
PWRGD3
VMONITOR
PWRGD
DC
GND
VCC
POL_SEL
VCC
IRF530
D1
30V
1N5256B
R2
49.9kΩ
1%
R3
3.4kΩ
1%
Figure 8. Overvoltage Detection
MAX5934/MAX5934A
Positive High-Voltage, Hot-Swap Controllers with
Selectable Fault Management and Status Polarity
______________________________________________________________________________________ 13
changes in currents flowing through the power-supply
traces. This can cause inductive voltage spikes that
could exceed 85V. Use wider traces or heavier trace
plating and connect a 0.1µF capacitor between VCC and
GND to minimize these inductive spikes. Use a transient
voltage suppressor (TVS) at the input to prevent damage
from voltage surges. An SMBJ54A is recommended.
Power-Up Sequence
At power-up, transistor Q1 (see the Typical Application
Circuit) is off until these three conditions are met:
•V
ON exceeds the turn-on threshold voltage
•V
CC exceeds the UVLO threshold
•V
TIMER stays below 1.233V
The voltage at GATE increases with a slope of 10µA/C1
(where C1 is shown in the Typical Application Circuit)
and IINRUSH = CLx 10µA / C1. When the voltage across
RSENSE goes too high, the inrush current is limited by
the internal current-limit circuitry that adjusts the GATE
voltage to keep a constant voltage across RSENSE.
Thermal Shutdown
If the MAX5934/MAX5934A die temperature reaches
+150°C, an overtemperature fault is generated. As a
result, GATE goes low and turns the external MOSFET
off. The MAX5934/MAX5934A die temperature must
cool down below +120°C before the overtemperature
fault condition is removed.
Board Layout and Bypassing
Kelvin connections are recommended for accurate cur-
rent sensing. Make sure the minimum trace width for
2oz copper is 1.5mm per amp. A width of 4mm per amp
is recommended.
Connect a resistive divider from VCC to ON as close as
possible to ON and have short traces from VCC and
GND. To decrease induced noise connect a 0.1µF
capacitor between ON and GND (see Figure 10).
The external MOSFET must be thermally coupled to the
MAX5934/MAX5934A to ensure proper thermal shut-
down operation.
OVERVOLTAGE WAVEFORMS
ISENSE
5A/div
TIMER
10V/div
IN
50V/div
GATE
50V/div
10µs/div
OUTPUT
50V/div
Figure 9. Overvoltage Waveforms
IRF530
Figure 10. Recommended Layout for R2, R3, and RSENSE
MAX5934/MAX5934A
Positive High-Voltage, Hot-Swap Controllers with
Selectable Fault Management and Status Polarity
14 ______________________________________________________________________________________
Chip Information
TRANSISTOR COUNT: 1573
PROCESS: BiCMOS
Typical Application Circuit
MAX5934
MAX5934A
ON
CL
OUT
GATESENSE
VCC
16 14 11
9
4
6
5
7
12
8
M1
R1
1kΩ
5%
RSENSE
0.025Ω
C1
10nF
R4
59kΩ
1%
R6
24kΩ
5%
R7
24kΩ
5%
R10
1kΩ
1%
R9
90kΩ
1%
SMBJ54A
VIN
GND
CTIMER
0.68µF
R8
24kΩ
5%
R5
3.57kΩ
1%
FB1
2
10
1
3
15
PWRGD1
PWRGD2
TIMER
LATCH/RETRY
VCC
FB2
PWRGD3
VMONITOR
DC
GND
VCC
POL_SEL
VCC
IRF530
PWRGD
R2
49.9kΩ
1%
R3
3.4kΩ
1%
RG
10Ω
5%
MAX5934/MAX5934A
Positive High-Voltage, Hot-Swap Controllers with
Selectable Fault Management and Status Polarity
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15
© 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
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.)
QSOP.EPS
E
1
1
21-0055
PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH
