19-2988; Rev 0; 9/03
1A, 76V, High-Efficiency MAXPower
Step-Down DC-DC Converter
General Description
The MAX5035 easy-to-use, high-efficiency, high-volt-
age, step-down DC-DC converter operates from an
input voltage up to 76V and consumes only 350µA qui-
escent current at no load. This pulse-width modulated
(PWM) converter operates at a fixed 125kHz switching
frequency at heavy loads, and automatically switches
to pulse-skipping mode to provide low quiescent cur-
rent and high efficiency at light loads. The MAX5035
includes internal frequency compensation simplifying
circuit implementation. The device uses an internal low-
on-resistance, high-voltage, DMOS transistor to obtain
high efficiency and reduce overall system cost. This
device includes undervoltage lockout, cycle-by-cycle
current limit, hiccup mode output short-circuit protec-
tion, and thermal shutdown.
The MAX5035 delivers up to 1A output current. External
shutdown is included, featuring 10µA (typ) shutdown
current. The MAX5035A/B/C versions have fixed output
voltages of 3.3V, 5V, and 12V, respectively, while the
MAX5035D features an adjustable output voltage from
1.25V to 13.2V.
The MAX5035 is available in space-saving 8-pin SO
and 8-pin plastic DIP packages and operates over the
industrial (0°C to +85°C) temperature range.
o
Fixed (3.3V, 5V, 12V) and Adjustable
(1.25V to 13.2V) Versions
o
1A Output Current
o
Efficiency Up to 94%
o
Internal 0.4Ω High-Side DMOS FET
o
350µA Quiescent Current at No Load, 10µA
Shutdown Current
o
Internal Frequency Compensation
o
Fixed 125kHz Switching Frequency
o
Thermal Shutdown and Short-Circuit Current
Limit
o
8-Pin SO and PDIP Packages
Features
o
Wide 7.5V to 76V Input Voltage Range
MAX5035
Ordering Information
PART
MAX5035AUSA
TEMP RANGE
0°C to +85°C
0°C to +85°C
0°C to +85°C
0°C to +85°C
0°C to +85°C
0°C to +85°C
0°C to +85°C
0°C to +85°C
PIN-
PACKAGE
8 SO
8 PDIP
8 SO
8 PDIP
8 SO
8 PDIP
8 SO
8 PDIP
OUTPUT
VOLTAGE
(V)
3.3
5.0
12
ADJ
Applications
Consumer Electronics
Industrial
Distributed Power
MAX5035AUPA
MAX5035BUSA
MAX5035BUPA
MAX5035CUSA
MAX5035CUPA
MAX5035DUSA
MAX5035DUPA
Typical Operating Circuit
V
IN
7.5V TO 76V
68µF
V
IN
BST
0.1µF
100µH
LX
ON/OFF
ON
R2
OFF
SGND
GND
FB
VD
0.1µF
D1
50SQ100
Pin Configuration
MAX5035
R1
V
OUT
5V
68µF
TOP VIEW
BST
VD
SGND
FB
1
2
3
4
8
LX
V
IN
GND
ON/OFF
7
6
5
MAX5035
SO/PDIP
________________________________________________________________
Maxim Integrated Products
1
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.
1A, 76V, High-Efficiency MAXPower
Step-Down DC-DC Converter
MAX5035
ABSOLUTE MAXIMUM RATINGS
(Voltages referenced to GND, unless otherwise specified.)
V
IN
.........................................................................-0.3V to +80V
SGND ....................................................................-0.3V to +0.3V
LX.................................................................-0.8V to (V
IN
+ 0.3V)
BST ...............................................................-0.3V to (V
IN
+ 10V)
BST (transient < 100ns) ................................-0.3V to (V
IN
+ 15V)
BST to LX................................................................-0.3V to +10V
BST to LX (transient < 100ns) ................................-0.3V to +15V
ON/OFF........................................................-0.3V to (V
IN
+ 0.3V)
VD...........................................................................-0.3V to +12V
FB
MAX5035A/MAX5035B/MAX5035C ...................-0.3V to +15V
MAX5035D .........................................................-0.3V to +12V
V
OUT
Short-Circuit Duration...........................................Indefinite
VD Short-Circuit Duration ..............................................Indefinite
Continuous Power Dissipation (T
A
= +70°C)
8-Pin PDIP (derate 9.1mW/°C above +70°C)...............727mW
8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW
Operating Temperature Range
MAX5035_U_ _ ...................................................0°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Junction Temperature ......................................................+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.
ELECTRICAL CHARACTERISTICS
(V
IN
= +12V, V
ON/OFF
= +12V, I
OUT
= 0, T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C. See the
Typical Application Circuit.)
PARAMETER
SYMBOL
MAX5035A
Input Voltage Range
V
IN
MAX5035B
MAX5035C
MAX5035D
Undervoltage Lockout
UVLO
MAX5035A
Output Voltage
V
OUT
MAX5035B
MAX5035C
Feedback Voltage
V
FB
V
IN
= 7.5V to 76V,
I
OUT
= 20mA to 1A
V
IN
= 7.5V to 76V,
I
OUT
= 20mA to 1A
V
IN
= 15V to 76V,
I
OUT
= 20mA to 1A
3.185
4.85
11.64
1.192
CONDITIONS
MIN
7.5
7.5
15
7.5
5.2
3.3
5.0
12
1.221
86
90
94
90
350
350
350
350
460
460
460
460
µA
%
3.415
5.15
12.36
1.250
V
V
TYP
MAX
76.0
76.0
76
76.0
V
V
UNITS
V
IN
= 7.5V to 76V, MAX5035D
V
IN
= 12V, I
LOAD
= 0.5A, MAX5035A
V
IN
= 12V, I
LOAD
= 0.5A, MAX5035B
Efficiency
η
V
IN
= 24V, I
LOAD
= 0.5A, MAX5035C
V
IN
= 12V, V
OUT
= 5V, I
LOAD
= 0.5A,
MAX5035D
V
FB
= 3.5V, V
IN
= 7.5V to 76V, MAX5035A
V
FB
= 5.5V, V
IN
= 7.5V to 76V, MAX5035B
V
FB
= 13V, V
IN
= 15V to 76V, MAX5035C
V
FB
= 1.3V, MAX5035D
Quiescent Supply Current
I
Q
2
_______________________________________________________________________________________
1A, 76V, High-Efficiency MAXPower
Step-Down DC-DC Converter
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +12V, V
ON/OFF
= +12V, I
OUT
= 0, T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C. See the
Typical Application Circuit.)
PARAMETER
Shutdown Current
Peak Switch Current Limit
Switch Leakage Current
Switch On-Resistance
PFM Threshold
FB Input Bias Current
ON/OFF CONTROL INPUT
ON/OFF Input-Voltage Threshold
ON/OFF Input-Voltage Hysteresis
ON/OFF Input Current
OSCILLATOR
Oscillator Frequency
Maximum Duty Cycle
VOLTAGE REGULATOR
Regulator Output Voltage
Dropout Voltage
Load Regulation
Thermal Resistance
(Junction to Ambient)
THERMAL SHUTDOWN
Thermal-Shutdown Junction
Temperature
Thermal-Shutdown Hysteresis
T
SH
T
HYST
+160
20
°C
°C
∆VD/∆I
VD
PACKAGE THERMAL CHARACTERISTICS
θ
JA
SO package (JEDEC 51)
DIP package (JEDEC 51)
170
110
°C/W
VD
V
IN
= 8.5V to 76V, I
L
= 0mA
7.5V
≤
V
IN
≤
8.5V, I
L
= 1mA
0 to 5mA
6.9
7.8
2.0
150
8.8
V
V
mV/mA
f
OSC
D
MAX
MAX5035D
109
125
95
135
kHz
%
V
ON/OFF
V
HYST
I
ON/OFF
V
ON/OFF
= 0V to V
IN
Rising trip point
1.53
1.69
100
10
150
1.85
V
mV
nA
SYMBOL
I
SHDN
I
LIM
I
OL
R
DS(ON)
I
PFM
I
B
(Note 1)
V
IN
= 76V, V
ON/OFF
= 0V, V
LX
= 0V
I
SWITCH
= 1A
Minimum switch current in any cycle
MAX5035D
55
-12
CONDITIONS
V
ON/OFF
= 0V, V
IN
= 7.5V to 76V
MIN
TYP
10
1.80
1
0.40
85
+0.01
0.80
110
+12
MAX
45
2.40
UNITS
µA
A
µA
Ω
mA
nA
MAX5035
Note 1:
Switch current at which current limit is activated.
_______________________________________________________________________________________
3
1A, 76V, High-Efficiency MAXPower
Step-Down DC-DC Converter
MAX5035
Typical Operating Characteristics
(V
IN
= 12V, V
ON/OFF
= 12V, T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C. See the
Typical Application
Circuit,
if applicable.)
OUTPUT VOLTAGE vs. TEMPERATURE
(MAX5035AUSA, V
OUT
= 3.3V)
MAX5035 toc01
OUTPUT VOLTAGE vs. TEMPERATURE
(MAX5035DUSA, V
OUT
= 5V)
MAX5035 toc02
LINE REGULATION
(MAX5035AUSA, V
OUT
= 3.3V)
I
OUT
= 0.1A
3.36
OUTPUT VOLTAGE (V)
I
OUT
= 1A
3.32
MAX5035 toc03
3.40
I
OUT
= 0.1A
3.36
I
OUT
= 1A
V
OUT
(V)
5.20
5.15
5.10
V
OUT
(V)
5.05
5.00
4.95
4.90
4.85
I
OUT
= 1A
I
OUT
= 0.1A
3.40
3.32
3.28
3.28
3.24
3.24
3.20
0
25
50
TEMPERATURE (°C)
75
100
4.80
0
25
50
TEMPERATURE (°C)
75
100
3.20
5
20
35
50
65
80
INPUT VOLTAGE (V)
LINE REGULATION
(MAX5035DUSA, V
OUT
= 5V)
MAX5035 toc04
LOAD REGULATION
(MAX5035AUSA, V
OUT
= 3.3V)
MAX5035 toc05
LOAD REGULATION
(MAX5035DUSA, V
OUT
= 5V)
MAX5035 toc06
5.20
5.15
OUTPUT VOLTAGE (V)
5.10
3.40
V
IN
= 76V
3.36
V
IN
= 7.5V, 24V
V
OUT
(V)
5.10
5.05
V
IN
= 24V
V
OUT
(V)
V
IN
= 7.5V
5.00
V
IN
= 76V
5.05
5.00
4.95
4.90
4.85
4.80
5
I
OUT
= 0.1A
3.32
I
OUT
= 1A
3.28
4.95
3.24
3.20
20
35
50
65
80
0
200
400
600
800
1000
INPUT VOLTAGE (V)
I
LOAD
(mA)
4.90
0
200
400
600
800
1000
I
LOAD
(mA)
4
_______________________________________________________________________________________
1A, 76V, High-Efficiency MAXPower
Step-Down DC-DC Converter
Typical Operating Characteristics (continued)
(V
IN
= 12V, V
ON/OFF
= 12V, T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C. See the
Typical Application
Circuit,
if applicable.)
EFFICIENCY vs. LOAD CURRENT
(MAX5035AUSA, V
OUT
= 3.3V)
MAX5035 toc07
MAX5035
EFFICIENCY vs. LOAD CURRENT
(MAX5035DUSA, V
OUT
= 5V)
MAX5035 toc08
EFFICIENCY vs. LOAD CURRENT
(MAX5035DUSA, V
OUT
= 12V)
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
V
IN
= 76V
V
IN
= 15V
V
IN
= 24V
V
IN
= 48V
MAX5035 toc09
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0
200
400
600
800
V
IN
= 7.5V
V
IN
= 12V
V
IN
= 24V
V
IN
= 48V
V
IN
= 76V
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
V
IN
= 7.5V
V
IN
= 12V
V
IN
= 24V
V
IN
= 48V
V
IN
= 76V
100
1000
0
200
400
600
800
1000
0
200
400
600
800
1000
LOAD CURRENT (mA)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
OUTPUT CURRENT LIMIT
vs. TEMPERATURE
MAX5035 toc10
OUTPUT CURRENT LIMIT
vs. INPUT VOLTAGE
MAX5035 toc11
QUIESCENT SUPPLY CURRENT
vs. TEMPERATURE
MAX5035 toc12
2.0
2.0
350
QUIESCENT SUPPLY CURRENT (µA)
OUTPUT CURRENT LIMIT (A)
1.5
OUTPUT CURRENT LIMIT (A)
1.7
320
1.4
290
1.0
1.1
260
0.5
MAX5035DUSA
V
OUT
= 5V
5% DROP IN V
OUT
0
25
50
TEMPERATURE (°C)
75
100
0.8
0
0.5
5
20
35
MAX5035DUSA
V
OUT
= 5V
5% DROP IN VOUT
50
65
80
230
200
0
25
50
TEMPERATURE (°C)
75
100
INPUT VOLTAGE (V)
QUIESCENT SUPPLY CURRENT
vs. INPUT VOLTAGE
MAX5035 toc13
SHUTDOWN CURRENT
vs. TEMPERATURE
MAX5035 toc14
SHUTDOWN CURRENT vs. INPUT VOLTAGE
MAX5035 toc15
350
QUIESCENT SUPPLY CURRENT (µA)
20
20
SHUTDOWN CURRENT (µA)
290
12
SHUTDOWN CURRENT (µA)
0
25
50
TEMPERATURE (°C)
75
100
320
16
16
12
260
8
8
230
4
4
200
6
16
26
36
46
56
66
76
INPUT VOLTAGE (V)
0
0
6
16
26
36
46
56
66
76
INPUT VOLTAGE (V)
_______________________________________________________________________________________
5
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