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 tradi-
tional 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 paral-
leling the primary side, dedicated pins allow for simultane-
ous wakeup or shutdown of all paralleled units, thus pre-
venting 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 pack-
age and operates over a wide -40°C to +125°C tempera-
ture range.
Warning: The MAX5051 is designed to work with high
voltages. Exercise caution.
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
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
Applications
MAX5051AUI*
-40°C to +85°C
28-TSSOP-EP**
● High-Efficiency, Isolated Telecom/Datacom
Power Supplies
●
48V and 12V Server Power Supplies
●
48V Power-Supply Modules
●
Industrial Power Supplies
*Contact
factory for availability.
**EP
= Exposed pad.
Pin Configuration appears at end of data sheet.
19-2964; Rev 2; 5/14
MAX5051
Parallelable, Clamped Two-Switch
Power-Supply Controller IC
Absolute Maximum Ratings
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
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
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.
Package Thermal Characteristics
(Note 1)
TSSOP
Junction-to-Ambient Thermal Resistance (θ
JA
)
..........42°C/W
Note 1:
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to
www.maximintegrated.com/thermal-tutorial.
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, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C. All driver, voltage-regulator, and refer-
ence outputs unconnected except for bypass capacitors.)
PARAMETER
SUPPLY CURRENT (AVIN, PVIN)
AVIN Standby Current
PVIN Standby Current
AVIN Supply Current
PVIN Supply Current
AVIN Input Voltage Range
+9V LDO (REG9)
PVIN Input Voltage Range
REG9 Output-Voltage Set Point
REG9 Line Regulation
REG9 Load Regulation
V
PVIN
V
REG9
Inferred from PVIN supply current test
V
PVIN
= 11V
V
PVIN
= 11V to 76V
I
REG9
= 0 to 80mA
11
8.3
0.1
250
76
9.0
V
V
mV/V
mV
I
ASTBY
I
PSTBY
I
AVIN
I
PVIN
V
AVIN
= V
PVIN
= 11V to 76V;
V
STARTUP
= V
CS
= 0V;
V
BST
= V
XFRMRH
= V
DRVDD
= V
REG9
;
RCFF floating
V
AVIN
= V
PVIN
= 11V to 76V;
V
CS
= 0V; V
BST
= V
DRVDD
= V
REG9
;
V
XFRMRH
= 0V; STARTUP,
RCFF floating
Inferred from AVIN supply current test
11
300
400
0.65
8
450
650
1
12
76
µA
µA
mA
mA
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
www.maximintegrated.com
Maxim Integrated
│
2
MAX5051
Parallelable, Clamped Two-Switch
Power-Supply Controller IC
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, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C. All driver, voltage-regulator, and refer-
ence outputs unconnected except for bypass capacitors.)
REG9 Dropout Voltage
PARAMETER
REG9 Undervoltage Lockout
Threshold
REG9 Undervoltage Lockout
Threshold Hysteresis
+5V LDO (REG5)
REG5 Output-Voltage Set Point
REG5 Load Regulation
REG5 Dropout Voltage
SOFT-START/REFERENCE (CSS)
Reference Voltage
Soft-Start Pullup Current
FB Input Range
FB Input Current
COMP Output Range
COMP Output Sink Current
COMP Output Source Current
Open-Loop Gain
Unity-Gain Bandwidth
FB Offset Voltage
COMP Output Slew Rate
PVIN Undervoltage Lockout
STT Threshold
STT Input Impedance
FLTINT Source Current
FLTINT Shutdown Threshold
FLTINT Restart Hysteresis
V
STT
R
STT
I
FLTINT
V
FLTINTSD
V
FLTINTHY
G
A
BW
V
OS
SR
V
CSS
I
CSS
V
FB
I
FB
Inferred from FB offset voltage test
V
FB
= V
REF
Inferred from FB offset voltage test
V
FB
= 3V
V
FB
= 0V
2.1V < V
COMP
<
6V
C
COMP
= 50pF, I
COMP
=
±5mA
V
FB
= 0 to 3V; V
COMP
= 2.1V to 6V;
I
COMP
= -5mA to +5mA
C
COMP
= 50pF
V
PVIN
rising
V
STT
rising
22
1.18
-3
1
23.5
1.24
100
25
1.30
2.1
20
30
80
3
+3
0
1.125
1.235
70
3
±250
6.0
1.255
V
µA
V
nA
V
mA
mA
dB
MHz
mV
v/µs
V
V
kΩ
μA
V
V
V
REG5
I
REG5
= 0 to 40mA
I
REG5
= 40mA, measured with respect
to V
REG9
0.5
4.8
5.1
50
V
mV
V
SYMBOL
I
REG9
= 80mA
CONDITIONS
V
REG9
falling
MIN
5.7
750
0.5
TYP
MAX
6.7
V
UNITS
V
mV
ERROR AMPLIFIER (CSS, FB, COMP)
PVIN UNDERVOLTAGE LOCKOUT (STT)
INTEGRATING FAULT PROTECTION (FLTINT)
www.maximintegrated.com
Maxim Integrated
│
3
MAX5051
Parallelable, Clamped Two-Switch
Power-Supply Controller IC
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, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C. All driver, voltage-regulator, and refer-
ence outputs unconnected except for bypass capacitors.)
PARAMETER
PWM Period
Maximum PWM Duty Cycle
Maximum RCOSC Frequency
Maximum SYNCIN Frequency
SYNCIN High-Level Voltage
SYNCIN Low-Level Voltage
SYNCIN Pulldown Resistor
SYNCIN Rising to SYNCOUT
Falling Delay
SYNCIN Falling to SYNCOUT
Rising Delay
SYNCOUT Voltage High
SYNCOUT Voltage Low
RCOSC Peak Trip Level
RCOSC Valley Trip Level
RCOSC Input Bias Current
RCOSC Discharge MOSFET
R
DS(ON)
RCOSC Discharge Pulse Width
UNDERVOLTAGE LOCKOUT (UVLO)
UVLO Threshold
UVLO Hysteresis
UVLO Input Bias Current
PWM COMPARATOR
RCFF Input Voltage Range
Feed-Forward Discharge
MOSFET R
DS(ON)
CON Input Voltage Range
RCFF Level-Shift Voltage
V
CPWM
R
DS(RCFF)
Sinking 10mA
0
2.2
0
50
3
100
6
2.4
V
Ω
V
V
V
UVLO
V
HYS
I
BUVLO
V
UVLO
= 2.5V
-100
V
UVLO
rising
1.18
1.24
130
+100
1.30
V
mV
nA
Sinking 10mA
V
TH
Sourcing 1.2mA
Sinking 2.4mA
2.5
0.2
-0.3
50
50
100
4.5
SYMBOL
t
S
D
MAX
f
RCOSCMAX
f
SYNCIN
VH
SYNCIN
VL
SYNCIN
50% duty cycle
Pulse rising
Pulse falling
100
30
70
5.1
0.3
2.1
0.8
CONDITIONS
R
RCOSC
= 24kΩ, C
RCOSC
= 100pF
R
RCOSC
= 24kΩ, C
RCOSC
= 100pF
MIN
TYP
3.9
48
1
500
MAX
UNITS
μs
%
MHz
kHz
V
V
kΩ
ns
ns
V
V
V
V
μA
Ω
ns
OSCILLATOR (RCOSC, SYNCIN, SYNCOUT)
www.maximintegrated.com
Maxim Integrated
│
4
MAX5051
Parallelable, Clamped Two-Switch
Power-Supply Controller IC
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, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C. All driver, voltage-regulator, and refer-
ence outputs unconnected except for bypass capacitors.)
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