EVALUATION KIT AVAILABLE
MAX5033
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
General Description
The MAX5033 easy-to-use, high-efficiency, high-voltage,
step-down DC-DC converter operates from an input voltage up to 76V and consumes only 270μA quiescent current at no load. This pulse-width modulated (PWM) converter operates at a fixed 125kHz switching frequency at
heavy loads, and automatically switches to pulseskipping
mode to provide low quiescent current and high efficiency
at light loads. The MAX5033 includes internal frequency
compensation simplifying circuit implementation. The
device uses an internal low-onresistance, 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 protection, and thermal shutdown.
The MAX5033 delivers up to 500mA output current. The
output current may be limited by the maximum power
dissipation capability of the package. External shutdown
is included, featuring 10μA (typ) shutdown current. The
MAX5033A/B/C versions have fixed output voltages of
3.3V, 5V, and 12V, respectively, while the MAX5033D features an adjustable output voltage, from 1.25V to 13.2V.
Features
●● Wide 7.5V to 76V Input Voltage Range
●● Fixed (3.3V, 5V, 12V) and Adjustable (1.25V to
13.2V) Voltage Versions
●● 500mA Output Current
●● Efficiency Up to 94%
●● Internal 0.4Ω High-Side DMOS FET
●● 270μA Quiescent Current at No Load, 10μA
Shutdown Current
●● Internal Frequency Compensation
●● Fixed 125kHz Switching Frequency
●● Thermal Shutdown and Short-Circuit Current Limit
●● 8-Pin SO and PDIP Packages
Ordering Information
PINPACKAGE
PART
TEMP RANGE
MAX5033AUSA
0°C to +85°C
8 SO
The MAX5033 is available in space-saving 8-pin SO and
8-pin plastic DIP packages and operates over the automotive (-40°C to +125°C) temperature range.
MAX5033AUPA
0°C to +85°C
8 PDIP
MAX5033BUSA
0°C to +85°C
8 SO
Applications
MAX5033BUPA
0°C to +85°C
8 PDIP
MAX5033AASA
MAX5033BASA
●● Consumer Electronics
●● Industrial
●● Distributed Power
0°C to +85°C
8 SO
MAX5033CUPA
0°C to +85°C
8 PDIP
MAX5033DASA
VIN
47µF
BST
0.1µF
MAX5033
220µH
LX
R1
ON/OFF
ON
OFF
R2
D1
50SQ100
GND
0°C to +85°C
8 SO
0°C to +85°C
8 PDIP
VD
0.1µF
This product is available in both leaded(Pb) and lead(Pb)-free
packages. To order the lead(Pb)-free package, add a + after
the part number.
Pin Configuration
BST
1
8
LX
VD
2
7
VIN
SGND
3
6
GND
FB
4
5
ON/OFF
MAX5033
SO/PDIP
19-2979; Rev 5; 4/14
ADJ
-40°C to +125°C 8 SO
33µF
FB
SGND
VOUT
5V, 0.5A
12
-40°C to +125°C 8 SO
MAX5033DUPA
VIN
7.5V TO 76V
5.0
-40°C to +125°C 8 SO
MAX5033DUSA
Typical Application Circuit
3.3
-40°C to +125°C 8 SO
MAX5033CUSA
MAX5033CASA
OUTPUT
VOLTAGE (V)
MAX5033
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
Absolute Maximum Ratings
(Voltages referenced to GND, unless otherwise specified.)
VIN .........................................................................-0.3V to +80V
SGND ....................................................................-0.3V to +0.3V
LX.................................................................-0.8V to (VIN + 0.3V)
BST...............................................................-0.3V to (VIN + 10V)
BST (transient < 100ns)................................-0.3V to (VIN + 15V)
BST to LX................................................................-0.3V to +10V
BST to LX (transient < 100ns) ................................-0.3V to +15V
ON/OFF ..................................................................-0.3V to +80V
VD...........................................................................-0.3V to +12V
FB
MAX5033A/MAX5033B/MAX5033C...................-0.3V to +15V
MAX5033D.........................................................-0.3V to +12V
VOUT Short-Circuit Duration (VIN ≤ 40V).....................Indefinite
VD Short-Circuit Duration..............................................Indefinite
Continuous Power Dissipation (TA = +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
MAX5033_U_ _...................................................0°C to +85°C
MAX5033_A_ _..............................................-40°C to +125°C
Storage Temperature Range.............................-65°C to +150°C
Junction Temperature.......................................................+150°C
Lead Temperature (soldering, 10s)...................................+300°C
Soldering Temperature (reflow)
SO, PDIP Lead(Pb)-free...............................................+260°C
SO, PDIP Containing lead (Pb)....................................+240°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 (MAX5033_U_ _)
(VIN = +12V, VON/OFF = +12V, IOUT = 0, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C. See the
Typical Operating Circuit.)
PARAMETER
Input Voltage Range
Undervoltage Lockout
Output Voltage
Feedback Voltage
Efficiency
Quiescent Supply Current
Shutdown Current
SYMBOL
VIN
CONDITIONS
VFB
η
IQ
ISHDN
MAX
76.0
MAX5033B
7.5
76.0
MAX5033C
15
76
MAX5033D
7.5
76.0
UVLO
VOUT
TYP
7.5
5.2
3.185
3.3
3.415
MAX5033B, VIN = 7.5V to 76V,
IOUT = 20mA to 500mA
4.85
5.0
5.15
MAX5033C, VIN = 15V to 76V,
IOUT = 20mA to 500mA
11.64
12
12.36
VIN = 7.5V to 76V, MAX5033D
1.192
1.221
1.250
VIN = 12V, ILOAD = 500mA, MAX5033A
86
VIN = 12V, ILOAD = 500mA, MAX5033B
90
VIN = 24V, ILOAD = 500mA, MAX5033C
94
VIN = 12V, VOUT = 5V, ILOAD = 500mA,
MAX5033D
90
VFB = 3.5V, VIN = 7.5V to 76V, MAX5033A
270
440
VFB = 5.5V, VIN = 7.5V to 76V, MAX5033B
270
440
VFB = 13V, VIN = 15V to 76V, MAX5033C
270
440
VFB = 1.3V, MAX5033D
270
440
VON/OFF = 0V, VIN = 7.5V to 76V
10
45
1.5
2.1
ILIM
(Note 1)
Switch Leakage Current
IOL
VIN = 76V, VON/OFF = 0V, VLX = 0V
0.95
1
UNITS
V
V
MAX5033A, VIN = 7.5V to 76V,
IOUT = 20mA to 500mA
Peak Switch Current Limit
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MIN
MAX5033A
V
V
%
µA
µA
A
µA
Maxim Integrated │ 2
MAX5033
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
Electrical Characteristics (MAX5033_U_ _) (continued)
(VIN = +12V, VON/OFF = +12V, IOUT = 0, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C. See the
Typical Operating Circuit.)
PARAMETER
Switch On-Resistance
PFM Threshold
FB Input Bias Current
SYMBOL
RDS(ON)
IPFM
IB
CONDITIONS
MIN
ISWITCH = 500mA
Minimum switch current in any cycle
TYP
MAX
UNITS
0.4
0.80
Ω
35
65
95
mA
MAX5033D
-150
+0.01
+150
nA
Rising trip point
1.53
1.69
1.85
ON/OFF CONTROL INPUT
ON/OFF Input-Voltage Threshold
VON/OFF
ON/OFF Input-Voltage Hysteresis
VHYST
ON/OFF Input Current
ON/OFF Operating Voltage Range
ION/OFF
100
10
VON/OFF = 0V to VIN
VON/OFF
V
mV
150
nA
76
V
135
kHz
OSCILLATOR
Oscillator Frequency
fOSC
Maximum Duty Cycle
DMAX
109
MAX5033D
125
95
%
VOLTAGE REGULATOR
Regulator Output Voltage
VD
Dropout Voltage
Load Regulation
VIN = 8.5V to 76V, IL = 0mA
6.9
7.5V ≤ VIN ≤ 8.5V, IL = 1mA
ΔVD/ΔIVD 0 to 5mA
7.8
8.8
V
2.0
V
150
Ω
PACKAGE THERMAL CHARACTERISTICS
Thermal Resistance
(Junction to Ambient)
θJA
SO package (JEDEC 51)
170
DIP package (JEDEC 51)
110
°C/W
THERMAL SHUTDOWN
Thermal-Shutdown Junction
Temperature
Thermal-Shutdown Hysteresis
TSH
+160
°C
THYST
20
°C
Electrical Characteristics (MAX5033_A_ _)
(VIN = +12V, VON/OFF = +12V, IOUT = 0, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. See the
Typical Operating Circuit.) (Note 2)
PARAMETER
Input Voltage Range
Undervoltage Lockout
Output Voltage
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SYMBOL
VIN
CONDITIONS
MIN
MAX
7.5
76.0
MAX5033B
7.5
76.0
MAX5033C
15
76
MAX5033D
7.5
76.0
UVLO
VOUT
TYP
MAX5033A
5.2
UNITS
V
V
MAX5033A, VIN = 7.5V to 76V,
IOUT = 20mA to 500mA
3.185
3.3
3.415
MAX5033B, VIN = 7.5V to 76V,
IOUT = 20mA to 500mA
4.825
5.0
5.175
MAX5033C, VIN = 15V to 76V,
IOUT = 20mA to 500mA
11.58
12
12.42
V
Maxim Integrated │ 3
MAX5033
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
Electrical Characteristics (MAX5033_A_ _) (continued)
(VIN = +12V, VON/OFF = +12V, IOUT = 0, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. See the
Typical Operating Circuit.) (Note 2)
PARAMETER
Feedback Voltage
Efficiency
Quiescent Supply Current
Shutdown Current
Peak Switch Current Limit
Switch Leakage Current
Switch On-Resistance
PFM Threshold
FB Input Bias Current
SYMBOL
VFB
η
IQ
ISHDN
CONDITIONS
VIN = 7.5V to 76V, MAX5033D
UNITS
V
86
90
VIN = 24V, ILOAD = 500mA, MAX5033C
94
VIN = 12V, VOUT = 5V, ILOAD = 500mA,
MAX5033D
90
VFB = 3.5V, VIN = 7.5V to 76V, MAX5033A
270
440
VFB = 5.5V, VIN = 7.5V to 76V, MAX5033B
270
440
VFB = 13V, VIN = 15V to 76V, MAX5033C
270
440
VFB = 1.3V, MAX5033D
270
440
VON/OFF = 0V, VIN = 7.5V to 76V
10
45
µA
1.5
2.1
A
IOL
VIN = 76V, VON/OFF = 0V, VLX = 0V
IB
MAX
1.250
VIN = 12V, ILOAD = 500mA, MAX5033B
(Note 1)
IPFM
TYP
1.221
VIN = 12V, ILOAD = 500mA, MAX5033A
ILIM
RDS(ON)
MIN
1.192
0.95
1
ISWITCH = 500mA
Minimum switch current in any cycle
%
0.4
µA
µA
0.80
Ω
35
65
110
mA
MAX5033D
-150
+0.01
+150
nA
Rising trip point
1.50
1.69
1.85
ON/OFF CONTROL INPUT
ON/OFF Input-Voltage Threshold
VON/OFF
ON/OFF Input-Voltage Hysteresis
VHYST
ON/OFF Input Current
ON/OFF Operating Voltage Range
ION/OFF
100
10
VON/OFF = 0V to VIN
VON/OFF
V
mV
150
nA
76
V
137
kHz
OSCILLATOR
Oscillator Frequency
fOSC
Maximum Duty Cycle
DMAX
105
MAX5033D
125
95
%
VOLTAGE REGULATOR
Regulator Output Voltage
VD
Dropout Voltage
Load Regulation
VIN = 8.5V to 76V, IL = 0mA
7.5V ≤ VIN ≤ 8.5V, IL = 1mA
ΔVD/ΔIVD 0 to 5mA
6.5
7.8
9.0
V
2.0
V
150
Ω
PACKAGE THERMAL CHARACTERISTICS
Thermal Resistance
(Junction to Ambient)
θJA
SO package (JEDEC 51)
170
DIP package (JEDEC 51)
110
°C/W
THERMAL SHUTDOWN
Thermal-Shutdown Junction
Temperature
Thermal-Shutdown Hysteresis
TSH
+160
°C
THYST
20
°C
Note 1: Switch current at which the current limit is activated.
Note 2: All limits at -40°C are guaranteed by design, not production tested.
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Maxim Integrated │ 4
MAX5033
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
Typical Operating Characteristics
(VIN = 12V, VON/OFF = 12V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. See the Typical Operating
Circuit, if applicable.)
12.3
IOUT = 0.1A
5.05
12.3
5.00
VOUT (V)
12.1
12.0
12.4
12.2
IOUT = 0.1A
VOUT (V)
IOUT = 0.5A
IOUT = 0.5A
4.95
11.9
25
0
4.90
100 125 150
75
50
-50
-25
LINE REGULATION
(MAX5033BASA, VOUT = 5V)
50 75 100 125 150
TEMPERATURE (C)
12.3
VOUT (V)
IOUT = 0.5A
30
VIN = 24V
12.1
12.0
VIN = 76V
4.95
40
50
60
70
80
LOAD REGULATION
(MAX5033BASA, VOUT = 5V)
VIN = 7.5V, 24V
5.05
12.2
5.00
20
5.10
MAX5033 toc05
IOUT = 0A
5.05
10
INPUT VOLTAGE (V)
LOAD REGULATION
(MAX5033CASA, VOUT = 12V)
12.4
MAX5033 toc04
5.10
11.8
25
0
VOUT (V)
-50 -25
TEMPERATURE (C)
VOUT (V)
12.1
12.0
IOUT = 0.5A
11.9
11.8
IOUT = 0A
MAX5033 toc06
VOUT (V)
12.2
LINE REGULATION
(MAX5033CASA, VOUT = 12V)
MAX5033 toc03
5.10
MAX5033 toc01
12.4
VOUT vs. TEMPERATURE
(MAX5033BASA, VOUT = 5V)
MAX5033 toc02
VOUT vs. TEMPERATURE
(MAX5033CASA, VOUT = 12V)
5.00
VIN = 76V
4.95
11.9
26
36
46
56
66
300
400
4.90
500
0
100
200
300
400
EFFICIENCY vs. LOAD CURRENT
(MAX5033BASA, VOUT = 5V)
EFFICIENCY vs. LOAD CURRENT
(MAX5033CASA, VOUT = 12V)
OUTPUT CURRENT LIMIT
vs. TEMPERATURE
60
VIN = 24V
50
VIN = 76V
90
80
VIN = 48V
30
70
60
30
20
10
300
LOAD CURRENT (mA)
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400
500
VIN = 24V
VIN = 48V
40
10
200
VIN = 76V
50
20
100
VIN = 15V
0
0
100
200
300
LOAD CURRENT (mA)
400
500
2.0
500
MAX5033 toc09
100
OUTPUT CURRENT LIMIT (A)
VIN = 7.5V
VIN = 12V
0
200
ILOAD (mA)
70
0
100
ILOAD (mA)
80
40
0
INPUT VOLTAGE (V)
90
EFFICIENCY (%)
11.8
76
MAX5033 toc07
100
16
MAX5033 toc08
6
EFFICIENCY (%)
4.90
1.7
1.4
1.1
0.8
0.5
MAX5033BASA
5% DROP IN VOUT
-50 -25
0
25 50 75 100 125 150
TEMPERATURE (°C)
Maxim Integrated │ 5
MAX5033
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
Typical Operating Characteristics (continued)
(VIN = 12V, VON/OFF = 12V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. See the Typical Operating
Circuit, if applicable.)
1.4
1.1
MAX5033BASA
VOUT = 5V
5% DROP IN VOUT
0.8
16
36
46
56
66
240
-50 -25
25
0
75
50
260
230
200
100 125 150
MAX5033 toc12
290
6
16
26
36
46
56
INPUT VOLTAGE (V)
SHUTDOWN CURRENT
vs. TEMPERATURE
SHUTDOWN CURRENT
vs. INPUT VOLTAGE
OUTPUT VOLTAGE
vs. INPUT VOLTAGE
5
0
20
15
10
5
0
25
50 75 100 125 150
TEMPERATURE (C)
MAX5033BASA
LOAD-TRANSIENT RESPONSE
MAX5033 toc16
76
MAX5033CASA
VOUT = 12V
VON/OFF = VIN
12
9
IOUT = 0.3A
IOUT = 0.5A
6
3
6
16
26
36
46
56
66
0
76
0
3
6
9
12
INPUT VOLTAGE (V)
VIN (V)
MAX5033BASA
LOAD-TRANSIENT RESPONSE
MAX5033BASA
LOAD-TRANSIENT RESPONSE
MAX5033 toc17
VOUT = 5V
15
VOUT (V)
10
25
66
MAX5033 toc15
TEMPERATURE (°C)
15
-50 -25
280
320
INPUT VOLTAGE (V)
20
0
320
200
76
MAX5033 toc13
SHUTDOWN CURRENT (µA)
25
26
360
QUIESCENT SUPPLY CURRENT
vs. INPUT VOLTAGE
350
MAX5033 toc14
6
SHUTDOWN CURRENT (µA)
0.5
MAX5033 toc11
1.7
400
QUIESCENT SUPPLY CURRENT (µA)
MAX5033 toc10
OUTPUT CURRENT LIMIT (A)
2.0
QUIESCENT SUPPLY CURRENT
vs. TEMPERATURE
QUIESCENT SUPPLY CURRENT (µA)
OUTPUT CURRENT LIMIT
vs. INPUT VOLTAGE
15
MAX5033 toc18
VOUT = 5V
VOUT = 5V
A
A
A
B
B
B
400µs/div
A: VOUT, 200mV/div, AC-COUPLED
B: IOUT, 500mA/div, 100mA TO 500mA
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400µs/div
A: VOUT, 100mV/div, AC-COUPLED
B: IOUT, 200mA/div, 100mA TO 250mA
400µs/div
A: VOUT, 100mV/div, AC-COUPLED
B: IOUT, 500mA/div, 250mA TO 500mA
Maxim Integrated │ 6
MAX5033
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
Typical Operating Characteristics (continued)
(VIN = 12V, VON/OFF = 12V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. See the Typical Operating
Circuit, if applicable.)
MAX5033BASA LX WAVEFORMS
MAX5033BASA LX WAVEFORMS
MAX5033BASA LX WAVEFORMS
MAX5033 toc20
MAX5033 toc19
MAX5033 toc21
A
A
A
0
0
0
B
B
B
0
0
4µs/div
4µs/div
A: SWITCH VOLTAGE, 20V/div, VIN = 48V
B: INDUCTOR CURRENT, 100mA/div (IOUT = 30mA)
MAX5033BASA STARTUP WAVEFORM
(IO = 0)
MAX5033BASA STARTUP WAVEFORM
(IO = 0.5A)
MAX5033 toc23
A
A
B
B
1ms/div
1ms/div
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A: VON/OFF, 2V/div
B: VOUT, 2V/div
PEAK SWITCH CURRENT LIMIT
vs. INPUT VOLTAGE
2.0
PEAK SWITCH CURRENT LIMIT (A)
MAX5033 toc22
A: VON/OFF, 2V/div
B: VOUT, 2V/div
A: SWITCH VOLTAGE (LX PIN), 20V/div, VIN = 48V
B: INDUCTOR CURRENT, 100mA/div (IOUT = 0)
MAX5033 toc24
4ms/div
A: SWITCH VOLTAGE (LX PIN) 20V/div, VIN = 48V
B: INDUCTOR CURRENT, 200mA/div, (IOUT = 500mA)
1.7
1.4
1.1
0.8
0.5
MAX5033BASA
VOUT = 5V
5% DROP IN VOUT
6
16
26
36
46
56
66
76
INPUT VOLTAGE (V)
Maxim Integrated │ 7
MAX5033
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
Pin Description
PIN
NAME
1
BST
Boost Capacitor Connection. Connect a 0.1μF ceramic capacitor from BST to LX.
FUNCTION
2
VD
Internal Regulator Output. Bypass VD to GND with a 0.1μF ceramic capacitor.
3
SGND
4
FB
5
ON/OFF
6
GND
7
VIN
Input Voltage. Bypass VIN to GND with a low-ESR capacitor as close to the device as possible.
8
LX
Source Connection of Internal High-Side Switch.
Internal Connection. SGND must be connected to GND.
Output Sense Feedback Connection. For fixed output voltage (MAX5033A, MAX5033B, MAX5033C),
connect FB to VOUT. For adjustable output voltage (MAX5033D), use an external resistive voltagedivider to set VOUT. VFB regulating set point is 1.22V.
Shutdown Control Input. Pull ON/OFF low to put the device in shutdown mode. Drive ON/OFF high
for normal operation.
Ground.
Simplified Block Diagram
VIN
ON/OFF
ENABLE
REGULATOR
(FOR ANALOG)
1.69V
REGULATOR
(FOR DRIVER)
VD
CPFM
OSC
VREF
IREF-PFM
HIGH-SIDE
CURRENT
SENSE
CILIM
RAMP
IREF-LIM
BST
MAX5033
CLK
FB
RAMP
CONTROL
LOGIC
Rh
x1
Rl
TYPE 3
COMPENSATION
VREF
EAMP
THERMAL
SHUTDOWN
CPWM
GND
LX
SGND
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Maxim Integrated │ 8
MAX5033
Detailed Description
The MAX5033 step-down DC-DC converter operates
from a 7.5V to 76V input voltage range. A unique voltage- mode control scheme with voltage feed-forward
and an internal switching DMOS FET provides high
efficiency over a wide input voltage range. This pulsewidth modulated converter operates at a fixed 125kHz
switching frequency. The device also features automatic
pulse-skipping mode to provide low quiescent current and
high efficiency at light loads. Under no load, the MAX5033
consumes only 270μA, and in shutdown mode, consumes
only 10μA. The MAX5033 also features undervoltage
lockout, hiccup-mode output shortcircuit protection, and
thermal shutdown.
Shutdown Mode
Drive ON/OFF to ground to shut down the MAX5033.
Shutdown forces the internal power MOSFET off, turns
off all internal circuitry, and reduces the VIN supply current to 10μA (typ). The ON/OFF rising threshold is 1.69V
(typ). Before any operation begins, the voltage at ON/OFF
must exceed 1.69V (typ). The ON/OFF input has 100mV
hysteresis.
Undervoltage Lockout (UVLO)
Use the ON/OFF function to program the UVLO threshold
at the input. Connect a resistive voltage-divider from VIN
to GND with the center node to ON/OFF as shown in
Figure 1. Calculate the threshold value by using the following formula:
R1
VUVLO(TH) =
1 + R2 × 1.85V
The minimum recommended VUVLO(TH) is 6.5V, 7.5V,
and 13V for the output voltages of 3.3V, 5V, and 12V,
respectively. The recommended value for R2 is less than
1MΩ.
If the external UVLO threshold-setting divider is not used,
an internal undervoltage-lockout feature monitors the
supply voltage at VIN and allows operation to start when
VIN rises above 5.2V (typ). This feature can be used only
when VIN rise time is faster than 2ms. For slower VIN rise
time, use the resistive divider at ON/OFF.
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
On startup, an internal low-side switch connects LX to
ground and charges the BST capacitor to VD. Once the
BST capacitor is charged, the internal low-side switch is
turned off and the BST capacitor voltage provides the
necessary enhancement voltage to turn on the high-side
switch.
Thermal-Overload Protection
The MAX5033 features integrated thermal-overload protection. Thermal-overload protection limits total power dissipation in the device, and protects the device in the event
of a fault condition. When the die temperature exceeds
+160°C, an internal thermal sensor signals the shutdown
logic, turning off the internal power MOSFET and allowing the IC to cool. The thermal sensor turns the internal
power MOSFET back on after the IC’s die temperature
cools down to +140°C, resulting in a pulsed output under
continuous thermaloverload conditions.
Applications Information
Setting the Output Voltage
The MAX5033A/B/C have preset output voltages of 3.3V,
5.0V, and 12V, respectively. Connect FB to the preset
output voltage (see the Typical Operating Circuit).
The MAX5033D offers an adjustable output voltage. Set
the output voltage with a resistive voltage-divider connected from the circuit’s output to ground (Figure 1). Connect
the center node of the divider to FB. Choose R4 less than
15kΩ, then calculate R3 as follows:
=
R3
(VOUT − 1.22)
× R4
1.22
VIN
7.5V TO 76V
47µF
R1
R2
220µH
VIN
LX
ON/OFF
BST
MAX5033D
Boost High-Side Gate Drive (BST)
Connect a flying bootstrap capacitor between LX and
BST to provide the gate-drive voltage to the high-side
n-channel DMOS switch. The capacitor is alternately
charged from the internally regulated output-voltage
VD and placed across the high-side DMOS driver. Use
a 0.1μF, 16V ceramic capacitor located as close to the
device as possible.
www.maximintegrated.com
0.1µF
D1
50SQ100
VOUT
5V, 0.5A
COUT
33µF
R3
41.2kΩ
FB
SGND
GND
VD
0.1µF
R4
13.3kΩ
Figure 1. Adjustable Output Voltage
Maxim Integrated │ 9
MAX5033
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
The MAX5033 features internal compensation for optimum closed-loop bandwidth and phase margin. With the
preset compensation, it is strongly advised to sense the
output immediately after the primary LC.
temperature rise and thermal shutdown. Use Table 1 to
choose the proper rectifier at different input voltages and
output current.
Inductor Selection
The discontinuous input-current waveform of the buck
converter causes large ripple currents in the input capacitor. The switching frequency, peak inductor current, and
the allowable peak-to-peak voltage ripple that reflects
back to the source dictate the capacitance requirement.
The MAX5033 high switching frequency allows the use of
smaller-value input capacitors.
The choice of an inductor is guided by the voltage difference between VIN and VOUT, the required output current,
and the operating frequency of the circuit. Use an inductor
with a minimum value given by:
L=
(VIN − VOUT ) × D
0.3 × I OUTMAX × f SW
where: D = VOUT/VIN, IOUTMAX is the maximum output
current required, and fSW is the operating frequency of
125kHz. Use an inductor with a maximum saturation current rating equal to at least the peak switch current limit
(ILIM). Use inductors with low DC resistance for higher
efficiency.
Selecting a Rectifier
The MAX5033 requires an external Schottky rectifier
as a freewheeling diode. Connect this rectifier close to
the device using short leads and short PC board traces.
Choose a rectifier with a continuous current rating greater
than the highest expected output current. Use a rectifier
with a voltage rating greater than the maximum expected
input voltage, VIN. Use a low forward-voltage Schottky
rectifier for proper operation and high efficiency. Avoid
higher than necessary reverse-voltage Schottky rectifiers
that have higher forward-voltage drops. Use a Schottky
rectifier with forward-voltage drop (VFB) less than 0.45V
at +25°C and maximum load current to avoid forward
biasing of the internal body diode (LX to ground). Internal
body-diode conduction may cause excessive junction
Table 1. Diode Selection
VIN (V)
7.5 to
36
7.5 to
56
7.5 to
76
DIODE PART NUMBER
MANUFACTURER
15MQ040N
IR
B240A
Diodes Incorporated
B240
Central Semiconductor
MBRS240, MBRS1540
ON Semiconductor
30BQ060
IR
B360A
Diodes Incorporated
CMSH3-60
Central Semiconductor
MBRD360, MBR3060
ON Semiconductor
50SQ100, 50SQ80
IR
MBRM5100
Diodes Incorporated
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Input Bypass Capacitor
The input ripple is comprised of ΔVQ (caused by the
capacitor discharge) and ΔVESR (caused by the ESR
of the capacitor). Use low-ESR aluminum electrolytic
capacitors with high ripple-current capability at the input.
Assuming that the contribution from the ESR and capacitor discharge is equal to 90% and 10%, respectively,
calculate the input capacitance and the ESR required for
a specified ripple using the following equations:
ESR IN =
C IN =
∆VESR
∆IL
I OUT +
2
I OUT × D(1 − D)
∆VQ × f SW
where :
(VIN − VOUT ) × VOUT
∆I L =
VIN × f SW × L
D=
VOUT
VIN
IOUT is the maximum output current of the converter and
fSW is the oscillator switching frequency (125kHz). For
example, at VIN = 48V and VOUT = 3.3V, the ESR and
input capacitance are calculated for the input peak-topeak
ripple of 100mV or less, yielding an ESR and capacitance
value of 130mΩ and 27μF, respectively.
Low-ESR, ceramic, multilayer chip capacitors are recommended for size-optimized application. For ceramic
capacitors, assume the contribution from ESR and capacitor discharge is equal to 10% and 90%, respectively.
The input capacitor must handle the RMS ripple current
without significant rise in temperature. The maximum
capacitor RMS current occurs at about 50% duty cycle.
Maxim Integrated │ 10
MAX5033
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
Ensure that the ripple specification of the input capacitor
exceeds the worst-case capacitor RMS ripple current.
Use the following equations to calculate the input capacitor RMS current:
=
I CRMS
IPRMS 2 − I AVGIN 2
where :
(IPK 2 + IDC 2 + (IPK × IDC)) × D3
IPRMS=
I AVGIN =
VOUT × I OUT
VIN × η
∆I
∆I
IPK =
I OUT + L , IDC =
I OUT − L
2
2
VOUT
and D =
VIN
IPRMS is the input switch RMS current, IAVGIN is the input
average current, and η is the converter efficiency.
The ESR of aluminum electrolytic capacitors increases
significantly at cold temperatures. Use a 1μF or greater
value ceramic capacitor in parallel with the aluminum
electrolytic input capacitor, especially for input voltages
below 8V.
Output Filter Capacitor
The worst-case peak-to-peak and RMS capacitor ripple
current, allowable peak-to-peak output ripple voltage, and
the maximum deviation of the output voltage during load
steps determine the capacitance and the ESR requirements for the output capacitors.
The output capacitance and its ESR form a zero, which
improves the closed-loop stability of the buck regulator.
Choose the output capacitor so the ESR zero frequency
(fZ) occurs between 20kHz to 40kHz. Use the following
equation to verify the value of fZ. Capacitors with 100mΩ
to 250mΩ ESR are recommended to ensure the closedloop stability while keeping the output ripple low.
fZ =
1
2 × π × C OUT × ESR OUT
The output ripple is comprised of ΔVOQ (caused by the
capacitor discharge) and ΔVOESR (caused by the ESR
of the capacitor). Use low-ESR tantalum or aluminum
electrolytic capacitors at the output. Assuming that the
contributions from the ESR and capacitor discharge equal
80% and 20%, respectively, calculate the output capacitance and the ESR required for a specified ripple using
the following equations:
www.maximintegrated.com
ESR OUT =
C OUT ≈
∆VOESR
∆IL
∆IL
2.2 × ∆VOQ × f SW
The MAX5033 has an internal soft-start time (tSS) of
400μs. It is important to keep the output rise time at
startup below tSS to avoid output overshoot. The output
rise time is directly proportional to the output capacitor.
Use 68μF or lower capacitance at the output to control the
overshoot below 5%.
In a dynamic load application, the allowable deviation of
the output voltage during the fast-transient load dictates
the output capacitance value and the ESR. The output
capacitors supply the step load current until the controller
responds with a greater duty cycle. The response time
(tRESPONSE) depends on the closedloop bandwidth of
the converter. The resistive drop across the capacitor
ESR and capacitor discharge cause a voltage droop during a step load. Use a combination of low-ESR tantalum
and ceramic capacitors for better transient load and
ripple/noise performance. Keep the maximum outputvoltage deviation above the tolerable limits of the electronics being powered. Assuming a 50% contribution from
the output capacitance discharge and the ESR drop, use
the following equations to calculate the required ESR and
capacitance value:
∆VOESR
ESR OUT =
I STEP
C OUT =
I STEP × t RESPONSE
∆VOQ
where ISTEP is the load step and tRESPONSE is the
response time of the controller. Controller response time
is approximately one-third of the reciprocal of the closedloop unity-gain bandwidth, 20kHz (typ).
PCB Layout Considerations
Proper PCB layout is essential. Minimize ground noise
by connecting the anode of the Schottky rectifier, the
input bypass-capacitor ground lead, and the output
filter-capacitor ground lead to a single point (star-ground
configuration). A ground plane is required. Minimize lead
lengths to reduce stray capacitance, trace resistance, and
radiated noise. In particular, place the Schottky rectifier
diode right next to the device. Also, place BST and VD
bypass capacitors very close to the device. Use the PCB
copper plane connecting to VIN and LX for heatsinking.
Maxim Integrated │ 11
MAX5033
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
Application Circuit
VIN
CIN
VIN
BST
MAX5033
R1
SGND
L1
D1
VOUT
COUT
FB
ON/OFF
R2
0.1µF
LX
GND
VD
0.1µF
Figure 2. Fixed Output Voltages
Table 2. Typical External Components Selection (Circuit of Figure 2)
VIN (V)
7.5 to 76
7.5 to 76
15 to 76
VOUT (V)
3.3
5
12
www.maximintegrated.com
IOUT (A)
EXTERNAL COMPONENTS
0.5
CIN = 47μF, Panasonic, EEVFK2A470Q
COUT = 47μF, Vishay Sprague, 594D476X_016C2T
CBST = 0.1μF, 0805
R1 = 1MΩ ±1%, 0805
R2 = 384kΩ ±1%, 0805
D1 = 50SQ100, IR
L1 = 150μH, Coilcraft Inc., DO5022P-154
0.5
CIN = 47μF, Panasonic, EEVFK2A470Q
COUT = 33μF, Vishay Sprague, 594D336X_016C2T
CBST = 0.1μF, 0805
R1 = 1MΩ ±1%, 0805
R2 = 384kΩ ±1%, 0805
D1 = 50SQ100, IR
L1 = 220μH, Coilcraft Inc., DO5022P-224
0.5
CIN = 47μF, Panasonic, EEVFK2A470Q
COUT = 15μF, Vishay Sprague, 594D156X_025C2T
CBST = 0.1μF, 0805
R1 = 1MΩ ±1%, 0805
R2 = 384kΩ ±1%, 0805
D1 = 50SQ100, IR
L1 = 330μH, Coilcraft Inc., DO5022P-334
Maxim Integrated │ 12
MAX5033
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
Table 2. Typical External Components Selection (Circuit of Figure 2) (continued)
VIN (V)
VOUT (V)
3.3
IOUT (A)
0.5
CIN = 100μF, Panasonic, EEVFK1E101P
COUT = 47μF, Vishay Sprague, 594D476X_016C2T
CBST = 0.1μF, 0805
R1 = 1MΩ ±1%, 0805
R2 = 274kΩ ±1%, 0805
D1 = B220/A, Diodes Incorporated
L1 = 150μH, Coilcraft Inc., DO5022P-154
0.5
CIN = 100μF, Panasonic, EEVFK1E101P
COUT = 33μF, Vishay Sprague, 594D336X_016C2T
CBST = 0.1μF, 0805
R1 = 1MΩ ±1%, 0805
R2 = 274kΩ ±1%, 0805
D1 = B220/A, Diodes Incorporated
L1 = 220μH, Coilcraft Inc., DO5022P-224
0.5
CIN = 100μF, Panasonic, EEVFK1H101P
COUT = 47μF, Vishay Sprague, 594D476X_016C2T
CBST = 0.1μF, 0805
R1 = 1MΩ ±1%, 0805
R2 = 130kΩ ±1%, 0805
D1 = B240/A, Diodes Incorporated
L1 = 150μH, Coilcraft Inc., DO5022P-154
0.5
CIN = 100μF, Panasonic, EEVFK1H101P
COUT = 33μF, Vishay Sprague, 594D336X_016C2T
CBST = 0.1μF, 0805
R1 = 1MΩ ±1%, 0805
R2 = 130kΩ ±1%, 0805
D1 = B240/A, Diodes Incorporated
L1 = 220μH, Coilcraft Inc., DO5022P-224
0.5
CIN = 100μF, Panasonic, EEVFK1H101P
COUT = 15μF, Vishay Sprague, 594D156X_025C2T
CBST = 0.1μF, 0805
R1 = 1MΩ ±1%, 0805
R2 = 130kΩ ±1%, 0805
D1 = B240/A, Diodes Incorporated
L1 = 330μH, Coilcraft Inc., DO5022P-334
9 to 14
5
3.3
18 to 36
5
12
www.maximintegrated.com
EXTERNAL COMPONENTS
Maxim Integrated │ 13
MAX5033
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
Table 3. Component Suppliers
PHONE
FAX
AVX
SUPPLIER
843-946-0238
843-626-3123
www.avxcorp.com
Coilcraft
847-639-6400
847-639-1469
www.coilcraft.com
Diodes Incorporated
805-446-4800
805-446-4850
www.diodes.com
Nichicon
858-824-1515
858-824-1525
www.nichicon.com
Panasonic
714-373-7366
714-737-7323
www.panasonic.com
SANYO
619-661-6835
619-661-1055
www.sanyo.com
TDK
847-803-6100
847-390-4405
www.component.tdk.com
Vishay
402-563-6866
402-563-6296
www.vishay.com
MAX5033
PTC*
ON/OFF
VIN
12V
VIN
CIN
47µF
Ct
Rt
WEBSITE
FB
BST
0.1µF
L1
220µH
LX
SGND GND
VD
0.1µF
D1
B240
VOUT
5V AT 0.5A
COUT
33µF
*LOCATE PTC AS CLOSE TO HEAT-DISSIPATING COMPONENTS AS POSSIBLE.
Figure 3. Load Temperature Monitoring with ON/OFF (Requires Accurate VIN)
www.maximintegrated.com
Maxim Integrated │ 14
MAX5033
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
MAX5033B
R1
ON/OFF
VIN
7.5V TO 36V
BST
0.1µF
VIN
CIN
47µF
Ct
Rt
FB
L1
220µH
LX
VD
SGND GND
VOUT
5V AT 0.5A
COUT
68µF
D1
B240
0.1µF
MAX5033A
FB
R1'
ON/OFF
VIN
C'IN
68µF
Ct'
Rt'
BST
0.1µF
L1'
150µH
LX
SGND GND
VD
V'OUT
3.3V AT 0.5A
D1'
B240
C'OUT
68µF
0.1µF
Figure 4. Dual-Sequenced DC-DC Converters (Startup Delay Determined by R1/R1’, Ct/Ct’ and Rt/Rt’)
Chip Information
PROCESS: BiCMOS
www.maximintegrated.com
Maxim Integrated │ 15
MAX5033
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”,
“#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
PACKAGE TYPE
PACKAGE CODE
OUTLINE NO.
LAND PATTERN NO.
8 PDIP
P8+3
21-0043
—
8 SO
S8+5
21-0041
90-0096
www.maximintegrated.com
Maxim Integrated │ 16
MAX5033
500mA, 76V, High-Efficiency, MAXPower
Step-Down DC-DC Converter
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
0
9/03
Initial release
1
5/04
New product update
1–7, 10
2
6/04
Removed future product asterisk and made specification changes
1, 2, 3
3
1/07
Modified Absolute Maximum Ratings specifications
4
4/10
Corrected inconsistencies in Absolute Maximum Ratings and Electrical
Characteristics table
5
4/14
No /V OPNs; removed Automotive reference in Applications section
DESCRIPTION
—
2
1, 2, 3, 4, 17
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
© 2014 Maxim Integrated Products, Inc. │ 17