19-0195; Rev 0; 10/93
Adjustable, Step-Down,
Current-Mode PWM Regulators
_______________General Description
The MAX750A/MAX758A are adjustable-output, CMOS,
step-down, DC-DC switching regulators. The
MAX758A accepts inputs from 4V to 16V and delivers
750mA, while the MAX750A accepts inputs from 4V to
11V and delivers 450mA. Typical efficiencies are 85%
to 90%. Typical quiescent current is 1.7mA, or only
6µA in shutdown mode. The output does not exhibit
any ripple at subharmonics of the switching frequency
over its specified range.
Pulse-width-modulation (PWM) current-mode control
provides precise output regulation and excellent tran-
sient responses. Output voltage accuracy is guaran-
teed to be ±4.5% plus feedback-resistor tolerance over
line, load, and temperature variations. Fixed-frequency
switching and absence of subharmonic ripple allows
easy filtering of output ripple and noise, as well as the
use of small external components. These regulators
require only a single inductor value to work in most
applications, so no inductor design is necessary.
____________________________Features
o
o
o
o
o
o
o
o
o
o
Up to 750mA Load Currents
160kHz High-Frequency, Current-Mode PWM
85% to 96% Efficiencies
33µH or 100µH Pre-Selected Inductor Value,
No Component Design Required
1.7mA Quiescent Supply Current
6µA Shutdown Supply Current
Adjustable Output Voltage
Overcurrent, Soft-Start, and Undervoltage
Lockout Protection
Cycle-by-Cycle Current Limiting
8-Pin DIP/SO Packages (MAX750A)
MAX750A/MAX758A
______________Ordering Information
PART
MAX750ACPA
MAX750ACSA
MAX750AC/D
MAX750AEPA
MAX750AESA
MAX750AMJA
TEMP. RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
PIN-PACKAGE
8 Plastic DIP
8 SO
Dice*
8 Plastic DIP
8 SO
8 CERDIP**
________________________Applications
Cellular Phones & Radios
Portable Communications Equipment
Portable Instruments
Computer Peripherals
Ordering Information continued on last page.
* Contact factory for dice specifications.
**Contact factory for availability and processing to MIL-STD-883.
_________________Pin Configurations
TOP VIEW
SHDN
REF
1
2
8
7
V+
LX
GND
I.C.
__________Typical Operating Circuit
INPUT
4V TO 16V
OUTPUT ADJ.
FROM
VREF TO V+
SS
3
CC
4
MAX750A
MAX758A
V+
LX
33µH
6
5
DIP
ON/OFF
SHDN
REF
1
2
8
7
V+
LX
GND
I.C.
MAX750A
MAX758A
SHDN
CC
SS
3
CC
4
MAX750A
REF
SS
GND
6
5
SO
Pin Configurations continued on last page.
________________________________________________________________
Maxim Integrated Products
1
Call toll free 1-800-998-8800 for free samples or literature.
Adjustable, Step-Down,
Current-Mode PWM Regulators
MAX750A/MAX758A
ABSOLUTE MAXIMUM RATINGS
Pin Voltages
V+ (MAX750A).........................................................+12V, -0.3V
V+ (MAX758A).........................................................+18V, -0.3V
LX (MAX750A) ....................................(V+ - 12V) to (V+ + 0.3V)
LX (MAX758A) ....................................(V+ - 21V) to (V+ + 0.3V)
SS, CC,
SHDN.............................................-0.3V
to (V+ + 0.3V)
Peak Switch Current (I
LX
).........................................................2A
Reference Current (I
REF
) ...................................................2.5mA
Power Dissipation (T
A
= +70°C)
8-Pin Plastic DIP (derate 9.09mW/°C above +70°C) .....727mW
8-Pin SO (derate 5.88mW/°C above +70°C)..................471mW
16-Pin Wide SO (derate 9.52mW/°C above +70°C) ......762mW
8-Pin CERDIP (derate 8.00mW/°C above +70°C)..........640mW
Operating Temperature Ranges:
MAX75_AC_ _ .......................................................0°C to +70°C
MAX75_AE_ _ ....................................................-40°C to +85°C
MAX75_AMJA ..................................................-55°C to +125°C
Junction Temperatures:
MAX75_AC_ _/AE_ _ ......................................................+150°C
MAX75_AMJA ................................................................+175°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+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.
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 3, V+ = 9V for the MAX750A, V+ = 12V for the MAX758A, V
OUT
= 5V, R2 = 40.20kΩ, R3 = 13.0kΩ, I
LOAD
= 0mA,
T
A
= T
MIN
to T
MAX
, unless otherwise noted.)
PARAMETER
CONDITIONS
V+ = 6.0V to 11.0V;
0mA < I
LOAD
< 450mA for MAX750AC,
0mA < I
LOAD
< 450mA for MAX750AE,
0mA < I
LOAD
< 300mA for MAX750AM
Output Voltage
(Note 1)
V+ = 6.0V to 16.0V;
0mA < I
LOAD
< 450mA for MAX758AC/AE,
0mA < I
LOAD
< 350mA for MAX758AM
V+ = 10.2V to 16.0V,
0mA < I
LOAD
< 750mA
Input Voltage Range
Line Regulation
Load Regulation
Efficiency
Supply Current
Shutdown Supply
Current (Note 2)
Shutdown Input
Threshold
Shutdown Input
Leakage Current
Short-Circuit Current
1.5
SHDN
= 0V
V
IH
V
IL
2.0
0.25
1.0
1.5
V+ = 4.0V to 11.0V
V+ = 4.0V to 16.0V
I
LOAD
= 0mA to 450mA
I
LOAD
= 0mA to 750mA
V+ = 9.0V, I
LOAD
= 300mA
V+ = 12V, I
LOAD
= 750mA
1.7
6.0
3.0
100.0
2.0
0.25
1.0
92
0.0005
0.0005
90
87
1.7
6.0
3.0
100.0
4.0
0.15
0.15
11.0
MIN
4.75
MAX750A
TYP
5.00
MAX
5.25
MIN
MAX758A
TYP
MAX
UNITS
4.75
5.00
5.25
V
4.75
4.0
5.00
5.25
16.0
V
%/V
%/mA
%
mA
µA
V
µA
A
2
_______________________________________________________________________________________
Adjustable, Step-Down,
Current-Mode PWM Regulators
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 3, V+ = 9V for the MAX750A, V+ = 12V for the MAX758A, V
OUT
= 5V, R2 = 40.20kΩ, R3 = 13.0kΩ, I
LOAD
= 0mA,
T
A
= T
MIN
to T
MAX
, unless otherwise noted.)
PARAMETER
Undervoltage
Lockout
LX On Resistance
LX Leakage Current
Reference Voltage
Reference Drift
Oscillator Frequency
Compensation Pin
Impedance
130
T
A
= +25°C
1.15
V+ rising
V+ falling
I
LX
= 500mA
CONDITIONS
MIN
MAX750A
TYP
3.75
3.5
0.5
1.0
1.22
50
170
7500
210
130
1.30
1.15
MAX
4.00
MIN
MAX758A
TYP
3.75
3.5
0.5
1.0
1.22
50
160
7500
190
1.30
MAX
4.00
UNITS
V
Ω
µA
V
ppm/°C
kHz
Ω
MAX750A/MAX758A
Note 1:
Output voltage tolerance over temperature is ±4.5% plus the tolerances of R3 and R4 in Figure 3.
Note 2:
The standby current typically settles to 25µA (over temperature) within 2 seconds; however, to decrease test time, the part
is guaranteed at a 100µA maximum value.
__________________________________________Typical Operating Characteristics
(Circuit of Figure 3, V
OUT
= 5V, T
A
= +25°C, unless otherwise noted.)
MAX750A
EFFICIENCY vs. OUTPUT CURRENT
MAX750A/58A-1
MAX758A
EFFICIENCY vs. OUTPUT CURRENT
(NOTES 3, 6)
90
EFFICIENCY (%)
MAX750A/58A-2
100
(NOTES 3, 6)
90
EFFICIENCY (%)
100
80
V+ = 5.5V
V+ = 7V
V+ = 9V
80
V+ = 6V
V+ = 8V
V+ = 12V
V+ = 16V
70
V+ = 11V
70
60
0
200
400
600
800
1000
OUTPUT CURRENT (mA)
60
0
200
400
600
800
1000
OUTPUT CURRENT (mA)
_______________________________________________________________________________________
3
Adjustable, Step-Down,
Current-Mode PWM Regulators
MAX750A/MAX758A
_____________________________Typical Operating Characteristics (continued)
(Circuit of Figure 3, V
OUT
= 5V, T
A
= +25°C, unless otherwise noted.)
MAX758A
PEAK INDUCTOR CURRENT
vs. OUTPUT CURRENT
MAX1750A/58A-4
MAX758A
PEAK INDUCTOR CURRENT
vs. OUTPUT CURRENT
600
500
400
300
200
100
0
V+ = 10.2V
V+ = 8.0V
V+ = 6.6V
V+ = 6.0V
0
50
100
150
200
250
300
L1 = 18µH
C4 = 1000µF
MAX1750A/58A-5
OSCILLATOR FREQUENCY
vs. SUPPLY VOLTAGE
(NOTE 3)
OSCILLATOR FREQUENCY (kHz)
210
200
190
MAX750A
180
170
MAX758A
160
150
4
6
8
10
12
14
16
MAX1750A/58A-6
1000
PEAK INDUCTOR CURRENT (mA)
L1 = 100µH
C4 = 300µF
800
700
PEAK INDUCTOR CURRENT (mA)
220
600
V+ 8.0V TO 16.0V
400
V+ = 6.6V
200
0
0
100 200 300 400 500 600 700 800
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
SUPPLY VOLTAGE (V)
MAX758A
NO-LOAD SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX1750A/58A-7
NO-LOAD SUPPLY CURRENT
vs. TEMPERATURE
MAX750A/58A-8
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
SHUTDOWN SUPPLY CURRENT (µA)
18
16
14
12
10
8
6
4
2
0
-60 -40 -20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
MAX758A ONLY, V+ = 16V
MAX758A ONLY, V+ = 12V
V+ = 9V
V+ = 6V
NO-LOAD SUPPLY CURRENT (mA)
NO-LOAD SUPPLY CURRENT (mA)
(NOTES 3, 5)
2.5
2.0
1.5
1.0
0.5
0
0
2
4
6
8
10
12
14
UNDERVOLTAGE
LOCKOUT V+ RISING
(OPERATION BEGINS)
(NOTES 4, 5)
2.5
2.0
1.5
1.0
0.5
MAX750A, V+ = 9.0V
MAX758A, V+ = 12.0V
(NOTES 4, 5)
UNDERVOLTAGE
LOCKOUT V+ FALLING
(OPERATION ENDS)
16
0
-60 -40 -20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
MAX750A
OSCILLATOR FREQUENCY vs. TEMPERATURE
240
OSCILLATOR FREQUENCY (kHz)
220
200
180
160
140
V+ = 7.0V
V+ = 9.0V
V+ = 11.0V
(NOTE 4)
MAX758A
OSCILLATOR FREQUENCY vs. TEMPERATURE
200
(NOTE 4)
190
180
170
160
150
140
130
V+ = 12.0V
V+ = 9.0V
V+ = 16.0V
V+ = 6.0V
OSCILLATOR FREQUENCY (kHz)
V+ = 5.5V
0
-60 -40 -20
0
20 40 60 80 100 120 140
TEMPERATURE (°C)
120
-60 -40 -20
0
20 40 60 80 100 120 140
TEMPERATURE (°C)
4
_______________________________________________________________________________________
MAX750A/58A-9
3.0
2.0
20
Adjustable, Step-Down,
Current-Mode PWM Regulators
_____________________________Typical Operating Characteristics (continued)
(Circuit of Figure 3, V
OUT
= 5V, T
A
= +25°C, unless otherwise noted.)
MAXIMUM OUTPUT CURRENT
vs. SUPPLY VOLTAGE, R1 OMITTED
MAX750A/58A-10
MAX750A/MAX758A
MAXIMUM OUTPUT CURRENT
vs. SUPPLY VOLTAGE
1400
MAXIMUM OUTPUT CURRENT (mA)
(NOTES 3, 6)
MAXIMUM OUTPUT CURRENT (mA)
(NOTES 3, 6)
1200
MAX758A
1200
MAX758A
1000
800
600
MAX750A
1000
MAX750A
400
200
800
4
6
8
10
12
14
16
SUPPLY VOLTAGE (V)
4
6
8
10
12
14
16
SUPPLY VOLTAGE (V)
MAX758A
SWITCHING WAVEFORMS
CONTINUOUS CONDUCTION
MAX758A
SWITCHING WAVEFORMS
DISCONTINUOUS CONDUCTION
MAX750A/58A-11
1400
12V
A
0V
200mA
0mA
5V
C
2µs/div
A: SWITCH VOLTAGE (LX PIN), 5V/div, 0V TO +12V
B: INDUCTOR CURRENT, 100mA/div
C: OUTPUT VOLTAGE RIPPLE, 50mV/div
COUT = 390µF, V+ = 12V, IOUT = 20mA
B
12V
A
0V
100mA
0mA
5V
B
C
2µs/div
A: SWITCH VOLTAGE (LX PIN), 5V/div, 0V TO +12V
B: INDUCTOR CURRENT, 200mA/div
C: OUTPUT VOLTAGE RIPPLE, 50mV/div
COUT = 390µF, V+ = 12V, IOUT = 150mA
_______________________________________________________________________________________
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