Rainbow Electronics MAX5071 User Manual
General Description
The MAX5070/MAX5071 BiCMOS, high-performance,
current-mode PWM controllers have all the features
required for wide input voltage range isolated/nonisolated
power supplies. These controllers are used for low- and
high-power universal input voltage and telecom power
supplies.
The MAX5070/MAX5071 contain a fast comparator with
only 60ns typical delay from current sense to the output
for overcurrent protection. The MAX5070A/MAX5070B
have an integrated error amplifier with the output at
COMP. Soft-start is achieved by controlling the COMP
voltage rise using external components.
The frequency is adjustable from 20kHz to 1MHz with
an external resistor and capacitor. The timing capacitor
discharge current is trimmed allowing for programmable dead time and maximum duty cycle for a given frequency. The available saw-toothed waveform at RTC
T
can be used for slope compensation when needed.
The MAX5071A/MAX5071B include a bidirectional syn-
chronization circuit allowing for multiple controllers to
run at the same frequency to avoid beat frequencies.
Synchronization is accomplished by simply connecting
the SYNC pins of all devices together. When synchronizing with other devices, the MAX5071A/MAX5071B
with the highest frequency synchronizes the other
devices. Alternatively, the MAX5071A/MAX5071B can
be synchronized to an external clock with an opendrain output stage running at a higher frequency.
The MAX5071C provides a clock output pulse
(ADV_CLK) that leads the driver output (OUT) by
110ns. The advanced clock signal is used to drive the
secondary-side synchronous rectifiers.
The MAX5070/MAX5071 are available in 8-pin µMAX
®
and SO packages and operate over the automotive temperature range of -40°C to +125°C.
Applications
Universal Input AC/DC Power Supplies
Isolated Telecom Power Supplies
Isolated Power-Supply Modules
Networking Systems
Computer Systems/Servers
Industrial Power Conversion
Isolated Keep-Alive Circuits
Features
♦ Pin-for-Pin Replacement for UC2842 (MAX5070A)
and UC2844 (MAX5070B)
♦ 2A Drive Source and 1A Sink Capability
♦ Up to 1MHz Switching Frequency Operation
♦ Bidirectional Synchronization
(MAX5071A/MAX5071B)
♦ Advanced Output Drive for Secondary-Side
Synchronous Rectification (MAX5071C)
♦ Fast 60ns Cycle-by-Cycle Current Limit
♦ Trimmed Oscillator Capacitor Discharge Current
Sets Maximum Duty Cycle Accurately
♦ Accurate 5% Start and Stop Voltage with 6V
Hysteresis
♦ Low 32µA Startup Current
♦ 5V Regulator Output (VREF) with 20mA Capability
♦ Overtemperature Shutdown
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
________________________________________________________________ Maxim Integrated Products 1
OUT
GNDR
T/CT
1
2
87VREF
V
CC
FB
CS
COMP
µMAX/SO
TOP VIEW
3
4
6
5
MAX5070A
MAX5070B
Pin Configurations
Ordering Information
19-3283; Rev 1; 6/04
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.
Ordering Information continued at end of data sheet.
Selector Guide appears at end of data sheet.
PART TEMP RANGE
PIN-PACKAGE
MAX5070AASA
8 SO
MAX5070AAUA
8 µMAX
MAX5070BASA
8 SO
MAX5070BAUA
8 µMAX
Pin Configurations continued at end of data sheet.
µMAX is a registered trademark of Maxim Integrated Products, Inc.
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC= +15V, RT= 10kΩ, CT= 3.3nF, V
VREF
= OPEN, C
VREF
= 0.1µF, COMP = OPEN, VFB= 2V, CS = GND, TA= -40°C to +85°C,
unless otherwise noted.) (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.
VCC(Low-Impedance Source) to GND..................-0.3V to +30V
V
CC(ICC
< 30mA).....................................................Self Limiting
OUT to GND...............................................-0.3V to (V
CC
+ 0.3V)
OUT Current.............................................................±1A for 10µs
FB, SYNC, COMP, CS, R
T/CT
, VREF to GND...........-0.3V to +6V
COMP Sink Current (MAX5070)..........................................10mA
Continuous Power Dissipation (T
A
= +70°C)
8-Pin µMAX (derate 4.5mW/°C above +70°C).............362mW
8-Pin SO (derate 5.9mW/°C above +70°C)...............470.6mW
Operating Temperature Range (Automotive)....-40°C to +125°C
Maximum Junction Temperature .....................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
PARAMETER SYMBOL CONDITIONS
MIN
TYP
MAX
UNITS
REFERENCE
Output Voltage V
VREF
TA = +25°C, I
VREF
= 1mA
V
Line Regulation ∆V
LINE
12V < V
CC
< 25V, I
VREF
= 1mA 0.4 4 mV
Load Regulation ∆V
LOAD
1mA < I
VREF
< 20mA 6 25 mV
Total Output Variation V
REFT
1mA < I
VREF
< 20mA, 12V < V
CC
< 25V 4.9 5.1 V
Reference Output-Noise Voltage
V
NOISE
10Hz < f < 10kHz, TA = +25°C 50 µV
Reference Output Short Circuit I
S_SC
V
VREF =
0V -30
mA
OSCILLATOR
Initial Accuracy TA = +25°C 51 54 57 kHz
Voltage Stability 12V < VCC < 25V 0.2 0.5 %
Temp Stability -40°C < TA < +85°C 0.5 %
RT/CT Voltage Ramp (
P-P
)V
RAMP
1.7 V
RT/CT Voltage Ramp Valley
1.1 V
Discharge Current I
DIS
V
RT/CT
= 2V, TA = +25°C 7.9 8.3 8.7 mA
Frequency Range f
OSC
20
kHz
ERROR AMPLIFIER (MAX5070A/MAX5070B)
FB Input Voltage V
FB
FB shorted to COMP
2.5
V
FB Input Bias Current I
B(FB)
µA
Open-Loop Voltage Gain A
VOL
2V ≤ V
COMP
≤ 4V
dB
Unity-Gain Bandwidth f
GBW
1
MHz
Power-Supply Rejection Ratio PSRR 12V ≤ VCC ≤ 25V (Note 2) 60 80 dB
COMP Sink Current I
SINK
VFB = 2.7V, V
COMP
= 1.1V 2 6 mA
COMP Source Current I
SOURCE
VFB = 2.3V, V
COMP
= 5V
mA
COMP Output High Voltage V
COMPH
VFB = 2.3V, R
COMP
= 15kΩ to GND 5 5.8 V
COMP Output Low Voltage V
COMPL
VFB = 2.7V, R
COMP
= 15kΩ to VREF 0.1 1.1 V
CURRENT-SENSE AMPLIFIER
Gain A
CS
(Notes 3, 4)
3
V/V
MAX5070A/B (Note 3)
1
Maximum Current-Sense Signal V
CS_MAX
V
COMP
= 5V, MAX5071_
V
4.950 5.000 5.050
-100 -180
V
RAMP_VALLEY
2.465
-0.01 -0.1
100
-0.5 -1.2 -1.8
2.85
0.95
0.84 0.935 1.03
1000
2.535
3.26
1.05
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VCC= +15V, RT= 10kΩ, CT= 3.3nF, V
VREF
= OPEN, C
VREF
= 0.1µF, COMP = OPEN, VFB= 2V, CS = GND, TA= -40°C to +85°C,
unless otherwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS
UNITS
Power-Supply Rejection Ratio PSRR 12V ≤ VCC ≤ 25V 70 dB
Input Bias Current I
CS
-1
µA
Delay From CS to OUT
50mV overdrive 60 ns
MOSFET DRIVER
OUT Low-Side On-Resistance
I
SINK
= 200mA 4.5 10 Ω
OUT High-Side On-Resistance
I
SOURCE
= 100mA 3.5 7 Ω
I
SOURCE
(Peak) I
SOURCE
C
OUT
= 10nF 2 A
I
SINK
(Peak) I
SINK
C
OUT
= 10nF 1 A
Rise Time t
r
C
OUT
= 1nF 15 ns
Fall Time t
f
C
OUT
= 1nF 22 ns
UNDERVOLTAGE LOCKOUT/STARTUP
Startup Voltage Threshold
16
V
Minimum Operating Voltage After
Turn-On
V
CC_MIN
9.2 10
V
Undervoltage-Lockout Hysteresis
6V
PWM
MAX5070A/MAX5071A
96
Maximum Duty Cycle D
MAX
MAX5070B/MAX5071B/MAX5071C 48
50
%
Minimum Duty Cycle D
MIN
0%
SUPPLY CURRENT
Startup Supply Current I
START
32 65 µA
Operating Supply Current I
CC
VFB = VCS = 0V 3 5 mA
Zener Bias Voltage at V
CC
V
Z
ICC = 25mA 24
V
THERMAL SHUTDOWN
Thermal Shutdown T
SHDN
°C
Thermal-Shutdown Hysteresis T
HYST
30 °C
SYNCHRONIZATION (MAX5071A/MAX5071B only) (Note 5)
SYNC Frequency Range f
SYNC
20
kHz
SYNC Clock Input High
Threshold
V
SYNCINH
3.5 V
SYNC Clock Input Low Threshold
V
SYNCINL
0.8 V
SYNC Clock Input Minimum
Pulse Width
ns
SYNC Clock Output High Level V
SYNCOH
1mA external pulldown 4.0 4.7 V
SYNC Clock Output Low Level V
SYNCOL
R
SYNC
= 5kΩ 0 0.1 V
SYNC Leakage Current I
SYNC
V
SYNC
= 0V
0.1 µA
MIN TYP MAX
t
CS_DELAY
V
RDS_ONL
V
RDS_ONH
V
CC_START
UVLO
HYST
15.2
94.5
49.8
26.5
+150
t
PW_SYNCIN
200
0.01
-2.5
16.8
10.8
97.5
1000
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(VCC= +15V, RT= 10kΩ, CT= 3.3nF, V
VREF
= OPEN, C
VREF
= 0.1µF, COMP = OPEN, VFB= 2V, CS = GND, TA= -40°C to +85°C,
unless otherwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS
UNITS
ADV_CLK (MAX5071C only)
ADV_CLK High Voltage
I
ADV_CLK
= 10mA source 2.4 3 V
ADV_CLK Low Voltage
I
ADV_CLK
= 10mA sink 0.4 V
ADV_CLK Output Pulse Width t
PULSE
85 ns
ADV_CLK Rising Edge to OUT
Rising Edge
t
ADV_CLK
ns
ADV_CLK Source and Sink
Current
I
ADV_CLK
10 mA
ELECTRICAL CHARACTERISTICS
(VCC= +15V, RT= 10kΩ, CT= 3.3nF, V
VREF
= OPEN, C
VREF
= 0.1µF, COMP = OPEN, VFB= 2V, CS = GND, TA= -40°C to +125°C,
unless otherwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS
MIN
TYP
MAX
UNITS
REFERENCE
Output Voltage V
VREF
TA = +25°C, I
VREF
= 1mA
V
Line Regulation ∆V
LINE
12V < V
CC
< 25V, I
VREF
= 1mA 0.4 4 mV
Load Regulation ∆V
LOAD
1mA < I
VREF
< 20mA 6 25 mV
Total Output Variation V
REFT
1mA < I
VREF
< 20mA, 12V < V
CC
< 25V 4.9 5.1 V
Reference Output Noise Voltage
V
NOISE
10Hz < f < 10kHz, TA = +25°C 50 µV
Reference Output Short Circuit I
S_SC
V
VREF
= 0V -30
mA
OSCILLATOR
Initial Accuracy TA = +25°C 51 54 57 kHz
Voltage Stability 12V < VCC < 25V 0.2 0.5 %
Temp Stability -40°C < TA < +125°C 1 %
RT/CT Voltage Ramp (
P-P
)V
RAMP
1.7 V
RT/CT Voltage Ramp Valley
1.1 V
Discharge Current I
DIS
V
RT/CT
= 2V, TA = +25°C 7.9 8.3 8.7 mA
Frequency Range f
OSC
20
kHz
ERROR AMPLIFIER (MAX5070A/MAX5070B)
FB Input Voltage V
FB
FB shorted to COMP
2.5
V
FB Input Bias Current I
B(FB)
µA
Open-Loop Voltage Gain A
VOL
2V ≤ V
COMP
≤ 4V
dB
Unity-Gain Bandwidth f
GBW
1
MHz
Power-Supply Rejection Ratio PSRR 12V ≤ VCC ≤ 25V (Note 2) 60 80 dB
COMP Sink Current I
SINK
V
FB
= 2.7V, V
COMP
= 1.1V 2 6 mA
COMP Source Current I
SOURCE
V
FB
= 2.3V, V
COMP
= 5V
mA
COMP Output High Voltage V
COMPH
V
FB
= 2.3V, R
COMP
=15kΩ to GND 5 5.8 V
COMP Output Low Voltage V
COMPL
V
FB
= 2.7V, R
COMP
= 15kΩ to VREF 0.1 1.1 V
V
ADV_CLKH
V
ADV_CLKL
MIN TYP MAX
110
4.950 5.000 5.050
-100 -180
V
RAMP_VALLEY
2.465
-0.01 -0.1
100
-0.5 -1.2 -1.8
1000
2.535
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
_______________________________________________________________________________________ 5
ELECTRICAL CHARACTERISTICS (continued)
(VCC= +15V, RT= 10kΩ, CT= 3.3nF, V
VREF
= OPEN, C
VREF
= 0.1µF, COMP = OPEN, VFB= 2V, CS = GND, TA= -40°C to +125°C,
unless otherwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS
UNITS
CURRENT-SENSE AMPLIFIER
Gain A
CS
(Notes 3, 4)
3
V/V
MAX5070A/B (Note 3)
1
Maximum Current-Sense Signal V
CS_MAX
V
COMP
= 5V, MAX5071_
V
Power-Supply Rejection Ratio PSRR 12V ≤ VCC ≤ 25V 70 dB
Input Bias Current I
CS
-1
µA
Delay From CS to OUT
50mV overdrive 60 ns
MOSFET DRIVER
OUT Low-Side On-Resistance
I
SINK
= 200mA 4.5 12 Ω
OUT High-Side On-Resistance
I
SOURCE
= 100mA 3.5 9 Ω
I
SOURCE
(Peak) I
SOURCE
C
OUT
= 10nF 2 A
I
SINK
(Peak) I
SINK
C
OUT
= 10nF 1 A
Rise Time t
r
C
OUT
= 1nF 15 ns
Fall Time t
f
C
OUT
= 1nF 22 ns
UNDERVOLTAGE LOCKOUT/STARTUP
Startup Voltage Threshold
16
V
Minimum Operating Voltage After
Turn-On
V
CC_MIN
9.2 10
V
Undervoltage-Lockout Hysteresis
6V
PWM
MAX5070A/MAX5071A
96
Maximum Duty Cycle D
MAX
MAX5070B/MAX5071B/MAX5071C 48
50
%
Minimum Duty Cycle D
MIN
0%
SUPPLY CURRENT
Startup Supply Current I
START
32 65 µA
Operating Supply Current I
CC
VFB = VCS = 0V 3 5 mA
Zener Bias Voltage at V
CC
V
Z
ICC = 25mA 24
V
THERMAL SHUTDOWN
Thermal Shutdown T
SHDN
°C
Thermal-Shutdown Hysteresis T
HYST
30 °C
SYNCHRONIZATION (MAX5071A/MAX5071B only, Note 5)
SYNC Frequency Range f
SYNC
20
kHz
SYNC Clock Input High
Threshold
3.5 V
SYNC Clock Input Low Threshold
V
SYNCINL
0.8 V
SYNC Clock Input Minimum
Pulse Width
ns
SYNC Clock Output High Level V
SYNCOH
1mA external pulldown 4.0 4.7 V
SYNC Clock Output Low Level V
SYNCOL
R
SYNC
= 5kΩ 0 0.1 V
MIN TYP MAX
2.85
0.95
0.84 0.935 1.03
t
CS_DELAY
V
RDS_ONL
V
RDS_ONH
V
CC_START
UVLO
HYST
15.2
94.5
49.8
26.5
+150
V
SYNCINH
t
PW_SYNCIN
200
3.26
1.05
-2.5
16.8
10.8
97.5
1000
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
6 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(VCC= +15V, RT= 10kΩ, CT= 3.3nF, V
VREF
= OPEN, C
VREF
= 0.1µF, COMP = OPEN, VFB= 2V, CS = GND, TA= -40°C to +125°C,
unless otherwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS
UNITS
SYNC Leakage Current I
SYNC
V
SYNC
= 0V
0.1 µA
ADV_CLK (MAX5071C only)
ADV_CLK High Voltage
I
ADV_CLK
= 10mA source 2.4 3 V
ADV_CLK Low Voltage
I
ADV_CLK
= 10mA sink 0.4 V
ADV_CLK Output Pulse Width t
PULSE
85 ns
ADV_CLK Rising Edge to OUT
Rising Edge
t
ADV_CLK
ns
ADV_CLK Source and Sink
Current
I
ADV_CLK
10 mA
Note 1:All devices are 100% tested at +25°C. All limits over temperature are guaranteed by design, not production tested.
Note 2: Guaranteed by design, not production tested.
Note 3: Parameter measured at trip point of latch with V
FB
= 0V (MAX5070A/MAX5070B only).
Note 4: Gain is defined as A = ∆V
COMP
/∆VCS, 0 ≤ VCS≤ 0.8V.
Note 5: Output Frequency equals oscillator frequency for MAX5070A/MAX5071A. Output frequency is one-half oscillator frequency
for MAX5070B/MAX5071B/MAX5071C.
BOOTSTRAP UVLO vs. TEMPERATURE
MAX5070 toc01
TEMPERATURE (°C)
V
CC
(V)
1109565 80-10 5 20 35 50-25
6
7
8
9
10
11
12
13
14
15
16
17
5
-40 125
HYSTERESIS
VCC FALLING
VCC RISING
STARTUP CURRENT vs. TEMPERATURE
MAX5070 toc02
TEMPERATURE (°C)
STARTUP CURRENT (µA)
1109565 80-10 5 20 35 50-25
29
30
31
32
33
34
35
36
37
38
39
40
28
-40 125
2.0
2.5
5.5
3.5
3.0
4.0
4.5
5.0
6.0
-40 -10 5 20-25 35 50 9580 11065 125
OPERATING SUPPLY CURRENT (ICC)
vs. TEMPERATURE AFTER STARTUP
(f
OSC
= fSW = 250kHz)
MAX5070 toc03
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
CT = 100pF
Typical Operating Characteristics
(VCC= 15V, TA = +25°C, unless otherwise noted.)
V
ADV_CLKH
V
ADV_CLKL
MIN TYP MAX
0.01
110
MAX5070/MAX5071
High-Performance, Single-Ended, Current-Mode
PWM Controllers
_______________________________________________________________________________________ 7
REFERENCE VOLTAGE (VREF)
vs. TEMPERATURE
MAX5070 toc04
TEMPERATURE (°C)
V
VREF
(V)
1109565 80-10 5 20 35 50-25-40 125
4.6
4.7
4.8
4.9
5.0
5.1
5.2
5.3
5.4
5.5
4.5
I
REF
= 20mA
I
REF
= 1mA
REFERENCE VOLTAGE (VREF)
vs. REFERENCE LOAD CURRENT
MAX5070 toc05
I
REF
(mA)
V
VREF
(V)
453015
4.80
4.85
4.90
4.95
5.00
5.05
5.10
5.15
5.20
5.25
4.75
0
REFERENCE VOLTAGE (VREF)
vs. V
CC
VOLTAGE
MAX5070 toc06
VCC (V)
V
VREF
(V)
24222018161412
4.995
5.000
5.005
5.010
4.990
10 26
I
REF
= 1mA
OSCILLATOR FREQUENCY (f
OSC
)
vs. TEMPERATURE
MAX5070 toc07
TEMPERATURE (°C)
OSCILLATOR FREQUENCY (kHz)
1109565 80-10 5 20 35 50-25-40 125
460
470
480
490
500
510
520
530
540
550
450
RT = 3.01kΩ
C
T
= 1nF
OSCILLATOR RT/CT DISCHARGE CURRENT
vs. TEMPERATURE
MAX5070 toc08
TEMPERATURE (°C)
R
T
/C
T
DISCHARGE CURRENT (mA)
1109565 80-10 5 20 35 50-25
8.05
8.10
8.15
8.20
8.25
8.30
8.35
8.40
8.45
8.50
8.55
8.60
8.00
-40 125
V
RT/CT
= 2V
MAXIMUM DUTY CYCLE
vs. TEMPERATURE
MAX5070 toc09
TEMPERATURE (°C)
DUTY CYCLE (%)
1109565 80-10 5 20 35 50-25-40 125
10
20
30
40
50
60
70
80
90
100
0
RT = 3.01kΩ
C
T
= 1nF
MAX5070A/MAX5071A
MAX5070B/MAX5071B/MAX5071C
MAX5070A/MAX5071A
MAXIMUM DUTY CYCLE vs. FREQUENCY
MAX5070 toc10
OSCILLATOR FREQUENCY (kHz)
DUTY CYCLE (%)
1200 1600
30
20
10
40
50
60
70
80
90
100
0
0400 800 2000
CT = 100pF
CT = 1nF
CT = 560pF
CT = 220pF
CURRENT-SENSE (CS) TRIP THRESHOLD
vs. TEMPERATURE
MAX5070 toc11
TEMPERATURE (°C)
CS THRESHOLD (V)
1109565 80-10 5 20 35 50-25-40 125
0.92
0.94
0.96
0.98
1.00
1.02
1.04
1.06
1.08
1.10
0.90
Typical Operating Characteristics (continued)
(VCC= 15V, TA = +25°C, unless otherwise noted.)
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