Rainbow Electronics MAX5051 User Manual
General Description
The MAX5051 is a clamped, two-switch power-supply
controller IC. This device can be used both in forward or
flyback configurations with input voltage ranges from 11V
to 76V. It provides comprehensive protection mechanisms against possible faults, resulting in very high reliability power supplies. When used in conjunction with secondary-side synchronous rectification, power-supply
efficiencies can easily reach 92% for a +3.3V output
power supply operated from a 48V bus. The integrated
high- and low-side gate drivers provide more than 2A of
peak gate-drive current to two external N-channel
MOSFETs. Low startup current reduces the power loss
across the bootstrap resistor. A feed-forward voltagemode topology provides excellent line rejection while
avoiding the pitfalls of traditional current-mode control.
The MAX5051 power-supply controller is primary as
well as secondary-side parallelable, allowing the
design of scaleable power systems when necessary.
When paralleling the primary side, dedicated pins allow
for simultaneous wakeup or shutdown of all paralleled
units, thus preventing current-hogging during startup or
fault conditions.
The MAX5051 generates a lookahead signal for driving
secondary-side synchronous MOSFETs. Special
primary-side synchronization inputs/outputs allow two
primaries to be operated 180° out of phase for increased
output power and lower input ripple currents.
The MAX5051 is available in a 28-pin TSSOP-EP
package and operates over a wide -40°C to +125°C
temperature range.
Warning: The MAX5051 is designed to work with
high voltages. Exercise caution.
Applications
High-Efficiency, Isolated Telecom/Datacom
Power Supplies
48V and 12V Server Power Supplies
48V Power-Supply Modules
42V Automotive Power Systems
Industrial Power Supplies
Features
♦ Wide Input Voltage Range, 11V to 76V
♦ Voltage Mode with Input Voltage Feed-Forward
♦ Ripple-Phased Parallel Topology for High
Current/Power Output
♦ 2A Integrated High- and Low-Side MOSFET
Drivers
♦ SYNCIN And SYNCOUT Pins Enable 180° Out-Of-
Phase Operation
♦ Programmable Brownout and Bootstrap UVLOs
♦ High-Side Driver Bootstrap Capacitor Precharge
Driver
♦ Low Current-Limit Threshold for High Efficiency
♦ Programmable Switching Frequency
♦ Reference Voltage Soft-Start for Startup Without
Overshoots
♦ Startup Synchronization with Multiple Paralleled
Primaries
♦ Programmable Integrating Current-Limit Fault
Protection
♦ Look-Ahead PWM Signal for Secondary-Side
Synchronous Rectifier Drivers
♦ Look-Ahead Drivers for Either A High-Speed
Optocoupler or Pulse Transformer
♦ Wide -40°C to +125°C Operating Range
♦ Thermally Enhanced 28-Pin TSSOP Package
MAX5051
Parallelable, Clamped Two-Switch
Power-Supply Controller IC
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
19-2964; Rev 0; 8/03
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
*EP = Exposed pad.
Pin Configuration appears at end of data sheet.
PART TEMP RANGE PIN-PACKAGE
MAX5051AUI -40°C to +125°C 28-TSSOP-EP*
MAX5051
Parallelable, Clamped Two-Switch
Power-Supply Controller IC
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(AVIN = 12V, PVIN = 12V, V
UVLO
= V
STT
= 3V, V
CON
= 3V, R
RCOSC
= 24kΩ, C
CSS
= 10nF, C
RCOSC
= 100pF, C
REG9
= 4.7µF,
C
REG5
= 4.7µF, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at TA= +25°C. All driver, voltage-regulator, and refer-
ence outputs unconnected except for bypass capacitors.)
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.
AVIN, PVIN, XFRMRH to GND................................-0.3V to +80V
BST to GND ............................................................-0.3V to +95V
BST, DRVH to XFRMRH..........................................-0.3V to +12V
REG9, DRVDD, DRVL to GND................................-0.3V to +12V
DRVB, LXVDD, LXL, LXH to GND ..........................-0.3V to +12V
UVLO, STT, COMP, CON to GND ..........................-0.3V to +12V
FLTINT, RCFF to GND ............................................-0.3V to +12V
REG5, CS, CSS, FB to GND .....................................-0.3V to +6V
STARTUP, SYNCIN to GND......................................-0.3V to +6V
SYNCOUT, RCOSC to GND .....................................-0.3V to +6V
PGND to GND .......................................................-0.3V to +0.3V
LXL, LXH Current Continuous...........................................±50mA
DRVL, DRVH Current Continuous...................................±100mA
DRVL, DRVH Peak Current (<500ns) ....................................±5A
PVIN, REG9 Continuous Current ....................................+120mA
REG5 Continuous Current ................................................+80mA
DRVB, RCFF, RCOSC, CSS Continuous Current .............±20mA
COMP, SYNCOUT Continuous Current ............................±20mA
REG9, REG5, and COMP Short to GND ....................Continuous
Continuous Power Dissipation (T
A
= +70°C)
28-Pin TSSOP (derate 23.8mW/°C above +70°C) .....1905mW
28-Pin TSSOP (θ
JA
)......................................................42°C/W
Operating Temperature Range .........................-40°C to +125°C
Maximum Junction Temperature (T
J
) ..............................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
SUPPLY CURRENT (AVIN, PVIN)
AVIN Standby Current I
PVIN Standby Current I
AVIN Supply Current I
PVIN Supply Current I
ASTBY
PSTBY
AVIN
PVIN
= V
AVIN
V
STARTUP
V
= V
BST
RCFF floating
V
= V
AVIN
= V
V
BST
STARTUP, RCFF floating
= 11V to 76V;
PVIN
= V
= 0V;
CS
= V
XFRMRH
PVIN
DRVDD
DRVDD
= 11V to 76V; VCS = 0V;
= V
REG9
; V
= V
REG9
XFRMRH
;
= 0V;
300 450 µA
400 650 µA
0.65 1 mA
812mA
V
AVIN Input Voltage Range Inferred from AVIN supply current test 11 76 V
+9V LDO (REG9)
PVIN Input Voltage Range V
REG9 Output-Voltage Set Point V
PVIN
REG9
REG9 Line Regulation V
REG9 Load Regulation I
REG9 Dropout Voltage I
REG9 Undervoltage Lockout
Threshold
REG9 Undervoltage Lockout
Threshold Hysteresis
Inferred from PVIN supply current test 11 76 V
V
= 11V 8.3 9.0 V
PVIN
= 11V to 76V 0.1 mV/V
PVIN
= 0 to 80mA 250 mV
REG9
= 80mA 0.5 V
REG9
V
falling 5.7 6.7 V
REG9
750 mV
+5V LDO (REG5)
REG5 Output-Voltage Set Point V
REG5
REG5 Load Regulation I
REG5 Dropout Voltage
= 0 to 40mA 50 mV
REG5
I
= 40mA, measured with respect
REG5
to V
REG9
4.8 5.1 V
0.5 V
MAX5051
Parallelable, Clamped Two-Switch
Power-Supply Controller IC
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(AVIN = 12V, PVIN = 12V, V
UVLO
= V
STT
= 3V, V
CON
= 3V, R
RCOSC
= 24kΩ, C
CSS
= 10nF, C
RCOSC
= 100pF, C
REG9
= 4.7µF,
C
REG5
= 4.7µF, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at TA= +25°C. All driver, voltage-regulator, and refer-
ence outputs unconnected except for bypass capacitors.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
SOFT-START/REFERENCE (CSS)
Reference Voltage V
Soft-Start Pullup Current I
ERROR AMPLIFIER (CSS, FB, COMP)
FB Input Range V
FB Input Current I
COMP Output Range Inferred from FB offset voltage test 2.1 6.0 V
COMP Output Sink Current VFB = 3V 20 mA
COMP Output Source Current VFB = 0V 30 mA
Open-Loop Gain G
Unity-Gain Bandwidth BW C
FB Offset Voltage V
COMP Output Slew Rate SR C
PVIN UNDERVOLTAGE LOCKOUT (STT)
PVIN Undervoltage Lockout V
STT Threshold V
STT Input Impedance R
INTEGRATING FAULT PROTECTION (FLTINT)
FLTINT Source Current I
FLTINT Shutdown Threshold V
FLTINT Restart Hysteresis V
OSCILLATOR (RCOSC, SYNCIN, SYNCOUT)
PWM Period t
Maximum PWM Duty Cycle D
Maximum RCOSC Frequency f
Maximum SYNCIN Frequency f
SYNCIN High-Level Voltage VH
SYNCIN Low-Level Voltage VL
SYNCIN Pulldown Resistor 100 kΩ
SYNCIN Rising to SYNCOUT
Falling Delay
SYNCIN Falling to SYNCOUT
Rising Delay
CSS
CSS
FB
FB
A
OS
STT
STT
FLTINT
FLTINTSDVFLTINT
FLTINTHY
S
MAX
RCOSCMAX
SYNCIN
SYNCIN
SYNCIN
1.215 1.235 1.255 V
70 µA
Inferred from FB offset voltage test 0 3 V
VFB = V
REF
2.1V < V
COMP
VFB = 0 to 3V; V
I
COMP
COMP
rising 22 23.5 25 V
PVIN
V
rising 1.18 1.24 1.30 V
STT
< 6V 80 dB
COMP
= 50pF, I
= -5mA to +5mA
= ±5mA 3 MHz
COMP
= 2.1V to 6V;
COMP
-3 +3 mV
= 50pF 1 V/µs
±250 nA
100 kΩ
V
= 0V 90 µA
FLTINT
= rising 2.9 V
0.9 V
R
R
RCOSC
RCOSC
= 24kΩ, C
= 24kΩ, C
= 100pF 3.9 µs
RCOSC
= 100pF 48 %
RCOSC
1 MHz
50% duty cycle 500 kHz
Pulse rising 2.1 V
Pulse falling 0.8 V
30 ns
70 ns
MAX5051
Parallelable, Clamped Two-Switch
Power-Supply Controller IC
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(AVIN = 12V, PVIN = 12V, V
UVLO
= V
STT
= 3V, V
CON
= 3V, R
RCOSC
= 24kΩ, C
CSS
= 10nF, C
RCOSC
= 100pF, C
REG9
= 4.7µF,
C
REG5
= 4.7µF, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at TA= +25°C. All driver, voltage-regulator, and refer-
ence outputs unconnected except for bypass capacitors.)
)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
SYNCOUT Voltage High Sourcing 1.2mA 4.5 5.1 V
SYNCOUT Voltage Low Sinking 2.4mA 0.3 V
RCOSC Peak Trip Level V
RCOSC Valley Trip Level 0.2 V
RCOSC Input Bias Current -0.3 µA
RCOSC Discharge MOSFET
R
DS(ON)
RCOSC Discharge Pulse Width 50 ns
UNDERVOLTAGE LOCKOUT (UVLO)
UVLO Threshold V
UVLO Hysteresis V
UVLO Input Bias Current I
PWM COMPARATOR
RCFF Input Voltage Range 0 3 V
Feed-Forward Discharge
MOSFET R
DS(ON)
CON Input Voltage Range 06V
RCFF Level-Shift Voltage V
CON Input Bias Current I
Propagation Delay to Output t
SYNCHRONOUS RECTIFIER PULSE TRANSFORMER DRIVER (LXVDD, LXH, LXL)
High-Side MOSFET R
Low-Side MOSFET R
DS(ON)
DS(ON)
LXH Rising to DRVL Rising Delay 90 ns
CURRENT-LIMIT COMPARATOR (CS)
Current-Limit Threshold Voltage V
Current-Limit Input Bias Current I
Propagation Delay to Output t
LOW-SIDE MOSFET DRIVER (DRVDD, DRVL, PGND)
Peak Source Current
Peak Sink Current
DRVL Resistance Sourcing I
DRVL Resistance Sinking I
TH
2.5 V
Sinking 10mA 50 100 Ω
V
UVLO
HYS
BUVLOVUVLO
R
DS(RCFF
CPWM
CON
dCPWM
R
DSLXH
R
DSLXL
ILIM
BILIM
dILIM
rising 1.18 1.24 1.30 V
UVLO
130 mV
= 2.5V -100 +100 nA
Sinking 10mA 50 100 Ω
2.2 2.4 V
-2 +2 µA
DRVH, DRVL = unconnected, overdrive =
50mV, measured from CON to DRVL
LXH sourcing 10mA, V
LXL sinking 10mA, V
LXVDD
LXVDD
= V
= V
REG5
REG5
3 6.5 12 Ω
2.0 5 10 Ω
90 ns
144 154 164 mV
0 < VCS < 0.3V -2 +2 µA
DRVH, DRVL = unconnected, overdrive =
10mV, measured from CS to DRVL
V
= 0V, pulse width < 100ns;
DRVL
V
= V
DRVDD
V
DRVL
V
DRVDD
DRVL
DRVL
REG9
= V
REG9
= V
REG9
= 50mA, V
= -50mA, V
, pulse width < 100ns;
= V
DRVDD
DRVDD
= V
REG9
REG9
100 ns
2A
5A
1.7 3.5 Ω
0.6 1.4 Ω
MAX5051
Parallelable, Clamped Two-Switch
Power-Supply Controller IC
_______________________________________________________________________________________ 5
ELECTRICAL CHARACTERISTICS (continued)
(AVIN = 12V, PVIN = 12V, V
UVLO
= V
STT
= 3V, V
CON
= 3V, R
RCOSC
= 24kΩ, C
CSS
= 10nF, C
RCOSC
= 100pF, C
REG9
= 4.7µF,
C
REG5
= 4.7µF, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at TA= +25°C. All driver, voltage-regulator, and refer-
ence outputs unconnected except for bypass capacitors.)
HIGH-SIDE MOSFET DRIVER (BST, DRVH, XFRMRH)
Peak Source Current
Peak Sink Current
DRVH Resistance Sourcing
DRVH Resistance Sinking
Skew Between Low-Side and
High-Side Drivers
BOOST CAPACITOR CHARGE MOSFET (DRVB)
DRVB Resistance Sourcing I
DRVB Resistance Sinking I
Delay from Clock Fall 200 ns
One-Shot Pulse Width 300 ns
STARTUP (STARTUP)
Startup Threshold V
Startup Threshold Hysteresis 330 mV
Internal Pullup Current I
S TARTU P P ul l d ow n M OS FE T
R
D S ( ON )
OVERTEMPERATURE SHUTDOWN
Shutdown Junction Temperature Temperature rising 150 °C
Hysteresis 10 °C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
STARTUPVSTARTUP
STARTUP
V
= GN D , p ul se w i d th < 100ns,
D RV H
= V
V
B S T
V
D RV H
= V
V
B S T
I
DRVH
V
XFRMRH
I
DRVH
V
XFRMRH
DRVB
DRVB
Sinking 10mA 50 100 Ω
, V
R E G9
= V
, p ul se w i d th < 100ns,
B S T
, V
R E G9
= 50mA, V
= 0V
= -50mA, V
= 0V
= 50mA 8 35 Ω
= 50mA 5 35 Ω
rising 1.4 2.1 V
X FR M R H
X FR M R H
BST
BST
= 0V
= 0V
= V
REG9
= V
REG9
,
,
2A
5A
1.7 3.5 Ω
0.6 1.4 Ω
0ns
50 µA
MAX5051
Parallelable, Clamped Two-Switch
Power-Supply Controller IC
6 _______________________________________________________________________________________
Typical Operating Characteristics
(V
AVIN
= V
PVIN
= 12V, V
UVLO
= V
STT
= 3V, V
CON
= 3V, R
RCOSC
= 24kΩ, C
CSS
= 10nF, C
RCOSC
= 100pF, C
REG9
= 4.7µF, C
REG5
=
4.7µF, T
A
= +25°C, unless otherwise noted.)
AVIN STANDBY CURRENT
vs. AVIN SUPPLY VOLTAGE
MAX5051 toc01
AVIN SUPPLY VOLTAGE (V)
AVIN STANDBY CURRENT (µA)
706040 503020
210
220
230
240
250
260
270
280
290
300
200
10 80
V
UVLO
= 0V
AVIN STANDBY CURRENT
vs. TEMPERATURE
MAX5051 toc02
TEMPERATURE (°C)
AVIN STANDBY CURRENT (µA)
1007525 500-25
210
220
230
240
250
260
270
280
200
190
180
-50 125
V
UVLO
= 0V
PVIN STANDBY CURRENT
vs. SUPPLY VOLTAGE
MAX5051 toc03
PVIN SUPPLY VOLTAGE (V)
PVIN STANDBY CURRENT (µA)
706050403020
100
200
300
400
500
600
0
10 80
V
UVLO
= 0V
PVIN STANDBY CURRENT
vs. TEMPERATURE
MAX5051 toc04
TEMPERATURE (°C)
PVIN STANDBY CURRENT (µA)
1007550250-25
100
200
300
400
500
600
0
-50 125
V
UVLO
= 0V
PVIN STARTUP VOLTAGE
vs. TEMPERATURE
MAX5051 toc05
TEMPERATURE (°C)
PVIN STARTUP VOLTAGE (V)
1007550250-25
23.1
23.2
23.3
23.4
23.5
23.6
23.0
-50 125
STT = FLOATING
REG9 OUTPUT VOLTAGE
vs. PVIN VOLTAGE
MAX5051 toc06
PVIN VOLTAGE (V)
REG9 OUTPUT VOLTAGE (V)
706050403020
8.793
8.796
8.799
8.802
8.805
8.970
10 80
REG9 OUTPUT VOLTAGE
vs. TEMPERATURE
MAX5051 toc07
TEMPERATURE (°C)
REG9 OUTPUT VOLTAGE (V)
1007525 500-25
8.72
8.74
8.76
8.78
8.80
8.82
8.84
8.86
8.88
8.90
8.70
-50 125
REG9 OUTPUT VOLTAGE
vs. REG9 OUTPUT CURRENT
MAX5051 toc08
REG9 OUTPUT CURRENT (mA)
REG9 OUTPUT VOLTAGE (V)
14012080 10040 6020
8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9
9.0
8.0
0 160
REG5 OUTPUT VOLTAGE
vs. REG5 OUTPUT CURRENT
MAX5051 toc09
REG5 OUTPUT CURRENT (mA)
REG5 OUTPUT VOLTAGE (V)
8070605040302010
4.4
4.8
5.2
5.6
6.0
4.0
090
MAX5051
Parallelable, Clamped Two-Switch
Power-Supply Controller IC
_______________________________________________________________________________________ 7
Typical Operating Characteristics (continued)
(V
AVIN
= V
PVIN
= 12V, V
UVLO
= V
STT
= 3V, V
CON
= 3V, R
RCOSC
= 24kΩ, C
CSS
= 10nF, C
RCOSC
= 100pF, C
REG9
= 4.7µF, C
REG5
=
4.7µF, TA= +25°C, unless otherwise noted.)
REG5 OUTPUT VOLTAGE
vs. TEMPERATURE
5.001
5.000
4.999
4.998
4.997
4.996
4.995
4.994
OUTPUT VOLTAGE (V)
4.993
4.992
4.991
4.990
-50 125
TEMPERATURE (°C)
MAX5051 toc10
1007525 500-25
SOFT-START/REFERENCE VOLTAGE
vs. TEMPERATURE
1.245
1.240
1.235
1.230
1.225
1.220
1.215
1.210
SOFT-START/REFERENCE VOLTAGE (V)
1.205
1.200
-50 125
TEMPERATURE (°C)
MAX5051 toc13
1007525 500-25
700
V
UVLO
600
500
400
300
200
AVIN SUPPLY CURRENT (µA)
100
0
-50 125
90
85
80
75
70
CSS SOFT-START CURRENT (µA)
65
60
-50 125
AVIN SUPPLY CURRENT
vs. TEMPERATURE
= 0V
TEMPERATURE (°C)
CSS SOFT-START CURRENT
vs. TEMPERATURE
TEMPERATURE (°C)
MAX5051 toc11
1007550250-25
MAX5051 toc14
1007550250-25
PVIN SUPPLY CURRENT
vs. TEMPERATURE
7.2
V
= 12V
PVIN
7.1
7.0
6.9
6.8
PVIN SUPPLY CURRENT (mA)
6.7
6.6
-50 125
TEMPERATURE (°C)
UVLO THRESHOLD vs. TEMPERATURE
1.240
1.235
1.230
1.225
1.220
UVLO (V)
1.215
1.210
1.205
1.200
-50 125
TEMPERATURE (°C)
1007550250-25
10075-25 0 25 50
MAX5051 toc12
MAX5051 toc15
STT STARTUP THRESHOLD
vs. TEMPERATURE
1.240
1.235
1.230
1.225
1.220
STT (V)
1.215
1.210
1.205
1.200
-50 125
TEMPERATURE (°C)
RCFF LEVEL-SHIFT VOLTAGE
FLTINT CURRENT vs. TEMPERATURE
95
MAX5051 toc16
10075-25 0 25 50
94
93
92
91
90
89
FLTINT CURRENT (µA)
88
87
86
85
-50 125
TEMPERATURE (°C)
1007525 500-25
2.30
2.29
MAX5051 toc17
2.28
2.27
2.26
2.25
2.24
2.23
RCFF LEVEL-SHIFT VOLTAGE (V)
2.22
2.21
2.20
-50 125
vs. TEMPERATURE
MAX5051 toc18
1007525 500-25
TEMPERATURE (°C)
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