EVALUATION KIT AVAILABLE
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
General Description
The MAX15462 high-efficiency, high-voltage, synchronous
step-down DC-DC converter with integrated MOSFETs
operates over a 4.5V to 42V input voltage range. The
converter delivers output current up to 300mA at 3.3V
(MAX15462A), 5V (MAX15462B), and adjustable output
voltages (MAX15462C). The device operates over the
-40°C to +125°C temperature range and is available in a
compact 8-pin (2mm x 2mm) TDFN package. Simulation
models are available.
The device employs a peak-current-mode control
architecture with a MODE pin that can be used to
operate the device in the pulse-width modulation (PWM)
or pulse-frequency modulation (PFM) control schemes.
PWM operation provides constant frequency operation at
all loads and is useful in applications sensitive to variable
switching frequency. PFM operation disables negative inductor current and additionally skips pulses at light loads for high
efficiency. The low-resistance on-chip MOSFETs ensure high
efficiency at full load and simplify the PCB layout.
To reduce input inrush current, the device offers an
internal soft-start. The device also incorporates an EN/
UVLO pin that allows the user to turn on the part at the
desired input-voltage level. An open-drain RESET pin can
be used for output-voltage monitoring.
Applications
●●
●●
●●
●●
●●
●●
Process Control
Industrial Sensors
4–20mA Current Loops
HVAC and Building Control
High-Voltage LDO Replacement
General-Purpose Point of Load
Ordering Information appears at end of data sheet.
Typical Operating Circuit
VIN
4.5V TO
42V CIN
1µF
VIN
EN/UVLO
LX
GND
MAX15462A
CVCC
1µF
VCC
MODE
19-7552; Rev 1; 2/17
RESET
VOUT
Benefits and Features
●● Eliminates External Components and Reduces
Total Cost
• No Schottky—Synchronous Operation for High
Efficiency and Reduced Cost
• Internal Compensation
• Internal Feedback Divider for Fixed 3.3V, 5V
Output Voltages
• Internal Soft-Start
• All-Ceramic Capacitors, Ultra-Compact Layout
●● Reduces Number of DC-DC Regulators to Stock
• Wide 4.5V to 42V Input Voltage Range
• Fixed 3.3V and 5V Output Voltage Options
• Adjustable 0.9V to 0.89 x VIN Output Voltage Option
• Delivers Up to 300mA Load Current
• Configurable Between PFM and Forced-PWM
Modes
●● Reduces Power Dissipation
• Peak Efficiency = 92%
• PFM Feature for High Light-Load Efficiency
• Shutdown Current = 2.2µA (typ)
●● Operates Reliably in Adverse Industrial Environments
• Hiccup-Mode Current Limit and Autoretry Startup
• Built-In Output Voltage Monitoring with Open-Drain
RESET Pin
• Programmable EN/UVLO Threshold
• Monotonic Startup into Prebiased Output
• Overtemperature Protection
• High Industrial -40°C to +125°C Ambient Operating
Temperature Range/-40°C to +150°C Junction
Temperature Range
L1
33µH
COUT
10µF
VOUT
3.3V,
300mA
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Absolute Maximum Ratings
Continuous Power Dissipation (TA = +70°C)
8-Pin TDFN (derate 6.2mW/°C above +70°C).............496mW
Junction Temperature.......................................................+150°C
Storage Temperature Range............................. -65°C to +150°C
Soldering Temperature (reflow)........................................ +260°C
Lead Temperature (soldering, 10s).................................. +300°C
VIN to GND.............................................................-0.3V to +48V
EN/UVLO to GND..................................................-0.3V to +48V
LX to GND..................................................... -0.3V to VIN + 0.3V
VCC, FB/VOUT, RESET to GND..............................-0.3V to +6V
MODE to GND..............................................-0.3V to VCC + 0.3V
LX total RMS Current......................................................±800mA
Output Short-Circuit Duration.....................................Continuous
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. Junction temperature greater than +125°C degrades operating lifetimes.
Package Thermal Characteristics (Note 1)
TDFN
Junction-to-Ambient Thermal Resistance (θJA).......+162°C/W
Junction-to-Case Thermal Resistance (θJC)..............+20°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
(VIN = 24V, VGND = 0V, CIN = CVCC = 1µF, VEN/UVLO = 1.5V, LX = MODE = RESET = unconnected; TA = -40°C to +125°C, unless
otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to GND, unless otherwise noted.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
42
V
INPUT SUPPLY (VIN)
Input Voltage Range
Input Shutdown Current
Input Supply Current
4.5
VIN
IIN-SH
VEN/UVLO = 0V, shutdown mode
2.2
4
µA
IQ-PFM
MODE = unconnected,
FB/VOUT = 1.03 x FB/VOUT-REG
95
160
µA
IQ-PWM
Normal switching mode, VIN = 24V
2.5
4
mA
ENABLE/UVLO (EN/UVLO)
EN/UVLO Threshold
VENR
VEN/UVLO rising
1.19
1.215
1.24
VENF
VEN/UVLO falling
1.06
1.09
1.15
V
+100
nA
VEN-TRUESD
EN/UVLO Input Leakage Current
IEN/UVLO
VEN/UVLO falling, true shutdown
0.75
VEN/UVLO = 42V, TA = +25°C
-100
6V < VIN < 42V, 0mA < IVCC < 10mA
4.75
5
5.25
V
13
30
50
mA
0.15
0.3
V
LDO (VCC)
VCC Output Voltage Range
VCC Current Limit
VCC Dropout
VCC UVLO
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VCC
IVCC-MAX
VCC = 4.3V, VIN = 12V
VCC-DO
VIN = 4.5V, IVCC = 5mA
VCC-UVR
VCC rising
4.05
4.18
4.3
VCC-UVF
VCC falling
3.7
3.8
3.95
V
Maxim Integrated │ 2
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Electrical Characteristics (continued)
(VIN = 24V, VGND = 0V, CIN = CVCC = 1µF, VEN/UVLO = 1.5V, LX = MODE = RESET = unconnected; TA = -40°C to +125°C, unless
otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to GND, unless otherwise noted.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
1.35
1.75
UNITS
POWER MOSFETs
High-Side pMOS On-Resistance
RDS-ONH
ILX = 0.3A
(sourcing)
Low-Side nMOS On-Resistance
RDS-ONL
ILX = 0.3A
(sinking)
LX Leakage Current
ILX-LKG
TA = +25°C
TA = TJ = +125°C
2.7
TA = +25°C
0.45
TA = TJ = +125°C
VEN/UVLO = 0V, VIN = 42V, TA = +25°C,
VLX = (VGND + 1V) to (VIN - 1V)
0.55
0.9
-1
Ω
Ω
+1
µA
ms
SOFT-START (SS)
Soft-Start Time
3.8
4.1
4.4
MODE = GND, MAX15462C
0.887
0.9
0.913
MODE = unconnected, MAX15462C
0.887
0.915
0.936
MAX15462C
-100
-25
MODE = GND, MAX15462A
3.25
3.3
3.35
MODE = unconnected, MAX15462A
3.25
3.35
3.42
MODE = GND, MAX15462B
4.93
5
5.07
MODE = unconnected, MAX15462B
4.93
5.08
5.18
tSS
FEEDBACK (FB)
FB Regulation Voltage
FB Leakage Current
VFB-REG
IFB
V
nA
OUTPUT VOLTAGE (VOUT)
VOUT Regulation Voltage
VOUT-REG
V
CURRENT LIMIT
Peak Current-Limit Threshold
IPEAK-LIMIT
0.49
0.56
0.62
A
Runaway Current-Limit Threshold
IRUNAWAY-
0.58
0.66
0.73
A
Negative Current-Limit
Threshold
ISINK-LIMIT
0.25
0.3
0.35
A
PFM Current Level
LIMIT
MODE = GND
IPFM
0.01
mA
0.13
A
TIMING
Switching Frequency
465
fSW
Events to Hiccup After Crossing
Runaway Current Limit
62.5
Hiccup Timeout
Maximum Duty Cycle
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535
1
FB/VOUT Undervoltage Trip Level
to Cause Hiccup
Minimum On-Time
500
64.5
Cycles
66.5
131
tON-MIN
DMAX
FB/VOUT = 0.98 x FB/VOUT-REG
89
kHz
%
ms
90
130
ns
91.5
94
%
Maxim Integrated │ 3
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Electrical Characteristics (continued)
(VIN = 24V, VGND = 0V, CIN = CVCC = 1µF, VEN/UVLO = 1.5V, LX = MODE = RESET = unconnected; TA = -40°C to +125°C, unless
otherwise noted. Typical values are at TA = +25°C. All voltages are referenced to GND, unless otherwise noted.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
LX Dead Time
TYP
MAX
5
UNITS
ns
RESET
FB/VOUT Threshold for RESET
Rising
FB/VOUT rising
93.5
95.5
97.5
%
FB/VOUT Threshold for RESET
Falling
FB/VOUT falling
90
92
94
%
RESET Delay After FB/VOUT
Reaches 95% Regulation
2
ms
RESET Output Level Low
IRESET = 5mA
0.2
V
RESET Output Leakage Current
VRESET = 5.5V, TA = +25°C
0.1
µA
MODE
MODE Internal Pullup Resistor
500
kΩ
166
°C
10
°C
THERMAL SHUTDOWN
Thermal-Shutdown Threshold
Thermal-Shutdown Hysteresis
Temperature rising
Note 2: Limits are 100% tested at TA = +25°C. Limits over the operating temperature range and relevant supply voltage range are
guaranteed by design and characterization.
www.maximintegrated.com
Maxim Integrated │ 4
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Typical Operating Characteristics
(VIN = 24V, VGND = 0V, CIN = CVCC = 1µF, VEN/UVLO = 1.5V, TA = +25°C, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
toc01
90
80
80
80
50
VIN = 36V
20
1
60
40
VIN = 36V
1
10
90
80
60.00
50.00
40.00
VIN = 36V
30.00
0.00
100
0
50
100
80
VIN = 24V
40
30
VIN = 36V
20
10
0
VIN = 6V
EFFICIENCY (%)
EFFICIENCY (%)
90
50
0
50
100
FIGURE 7 APPLICATION
CIRCUIT, PWM MODE
VOUT = 2.5V
150
200
LOAD CURRENT (mA)
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200
250
70
VIN = 24V
60
50
VIN = 36V
40
30
FIGURE 6 APPLICATION
CIRCUIT, PWM MODE
VOUT = 5V
10
0
300
0
50
250
300
toc04b
50
VIN = 36V
30
FIGURE 8 APPLICATION
CIRCUIT, PWM MODE
VOUT = 12V
20
10
0
50
100
150
200
LOAD CURRENT (mA)
200
250
300
250
300
toc05
FIGURE 5 APPLICATION
CIRCUIT, PFM MODE
VOUT = 3.3V
3.35
VIN = 24V
40
150
OUTPUT VOLTAGE
vs. LOAD CURRENT
3.37
VIN = 18V
60
0
100
3.36
70
VIN = 12V
LOAD CURRENT (mA)
EFFICIENCY VS. LOAD CURRENT
100
80
VIN = 12V
150
100
EFFICIENCY vs. LOAD CURRENTtoc04
LOAD CURRENT (mA)
90
60
10
20
FIGURE 5 APPLICATION
CIRCUIT, PWM MODE
VOUT = 3.3V
10.00
EFFICIENCY vs. LOAD CURRENT toc04a
70
VIN = 12V
VIN = 24V
LOAD CURRENT (mA)
100
1
100
80.00
70.00
FIGURE 7 APPLICATION
CIRCUIT, PFM MODE
VOUT = 2.5V
VIN = 36V
LOAD CURRENT (mA)
90.00
20.00
FIGURE 8 APPLICATION
CIRCUIT, PFM MODE
VOUT = 12V
50
20
100
VIN = 6V
VIN = 24V
50
30
EFFICIENCY vs. LOAD CURRENT toc03
100.00
EFFICIENCY (%)
80
VIN = 24V
10
VIN = 12V
60
40
FIGURE 6 APPLICATION
CIRCUIT, PFM MODE
VOUT = 5V
1
70
LOAD CURRENT (mA)
90
VIN = 18V
VIN = 12V
VIN = 36V
20
10
100
LOAD CURRENT (mA)
70
50
30
EFFICIENCY vs. LOAD CURRENT toc02b
100
60
40
FIGURE 5 APPLICATION
CIRCUIT, PFM MODE
VOUT = 3.3V
30
VIN = 24V
EFFICIENCY (%)
VIN = 24V
70
OUTPUT VOLTAGE (V)
60
VIN = 12V
EFFICIENCY (%)
90
70
EFFICIENCY vs. LOAD CURRENTtoc02a
100
90
40
EFFICIENCY (%)
EFFICIENCY vs. LOAD CURRENT toc02
100
EFFICIENCY (%)
EFFICIENCY (%)
100
VIN = 24V
3.34
VIN = 12V
3.33
VIN = 36V
3.32
3.31
3.3
3.29
0
50
100
150
200
250
300
LOAD CURRENT (mA)
Maxim Integrated │ 5
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Typical Operating Characteristics (continued)
(VIN = 24V, VGND = 0V, CIN = CVCC = 1µF, VEN/UVLO = 1.5V, TA = +25°C, unless otherwise noted.)
OUTPUT VOLTAGE (V)
VIN = 12V
5.04
VIN = 36V
5.02
5
VIN = 36V
2.5
2.49
50
100
150
200
250
2.48
300
0
50
LOAD CURRENT (mA)
toc06c
VIN = 6V,24V
VIN = 36V
0.9
50
100
150
200
250
OUTPUT VOLTAGE (V)
12.05
0
50
VIN = 12V
0
50
VIN = 24V
100
150
250
5.001
VIN = 24V
MAX15462 toc09
FIGURE 5 APPLICATION
CIRCUIT, LOAD = 300mA
-40
-20
0
20
40
60
TEMPERATURE (°C)
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80
100 120
300
4.999
4.998
4.996
300
toc08
VIN = 36V
5
VIN = 12V
0
50
100
150
200
250
300
OUTPUT VOLTAGE vs. TEMPERATURE
5.02
5.00
4.98
4.96
3.28
250
FIGURE 5 APPLICATION
CIRCUIT, PWM MODE
VOUT = 5V
4.997
5.04
3.29
200
LOAD CURRENT (mA)
OUTPUT VOLTAGE
vs. TEMPERATURE
3.30
150
5.002
VIN = 36V
200
100
OUTPUT VOLTAGE
vs. LOAD CURRENT
LOAD CURRENT (mA)
3.31
3.27
12.1
5.003
3.299
3.297
300
toc07
3.3
LOAD CURRENT (mA)
3.32
12.15
LOAD CURRENT (mA)
3.301
3.298
0
VIN = 24V
VIN = 36V
12
300
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
VIN = 12V
0.895
250
FIGURE 5 APPLICATION
CIRCUIT, PWM MODE
VOUT = 3.3V
3.302
0.915
0.905
200
OUTPUT VOLTAGE
vs. LOAD CURRENT
3.303
PFM MODE
0.91
150
VIN = 18V
12.2
LOAD CURRENT (mA)
FEEDBACK VOLTAGE
vs. LOAD CURRENT
0.92
100
12.25
MAX15462 toc10
0
toc06b
FIGURE 8 APPLICATION
CIRCUIT, PFM MODE
VOUT = 12V
12.3
VIN = 6V,24V
2.51
OUTPUT VOLTAGE
vs. LOAD CURRENT
12.35
VIN = 12V
2.52
OUTPUT VOLTAGE (V)
4.98
toc06a
FIGURE 7 APPLICATION
CIRCUIT, PFM MODE
VOUT = 2.5V
2.53
VIN = 24V
5.06
OUTPUT VOLTAGE
vs. LOAD CURRENT
2.54
FIGURE 6 APPLICATION
CIRCUIT, PFM MODE
VOUT = 5V
5.08
OUTPUT VOLTAGE (V)
toc06
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE
vs. LOAD CURRENT
5.1
4.94
FIGURE 6 APPLICATION
CIRCUIT, LOAD = 300mA
-40
-20
0
20
40
60
80
100 120
TEMPERATURE (°C)
Maxim Integrated │ 6
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Typical Operating Characteristics (continued)
(VIN = 24V, VGND = 0V, CIN = CVCC = 1µF, VEN/UVLO = 1.5V, TA = +25°C, unless otherwise noted.)
FEEDBACK VOLTAGE
VS. TEMPERATURE
NO-LOAD SUPPLY CURRENT (µA)
0.908
0.900
0.896
0.892
0.888
0.884
-20
0
20
40
60
80
100
96
94
92
90
120
TEMPERATURE (°C)
120
45
55
110
100
90
80
5
4
3
2
1
70
PFM MODE
-40 -20
0
20
40
60
80
0
100 120
15
5
2.25
2.10
1.95
1.80
1.65
550
0
20
40
60
80
TEMPERATURE (°C)
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100 120
55
450
400
350
300
200
-20
45
SWITCH PEAK CURRENT LIMIT
500
SWITCH NEGATIVE CURRENT LIMIT
250
-40
35
SWITCH CURRENT LIMIT
vs. INPUT VOLTAGE
600
SWITCH CURRENT LIMIT (mA)
MAX15462 toc14
SHUTDOWN CURRENT
vs. TEMPERATURE
2.40
25
INPUT VOLTAGE (V)
TEMPERATURE (°C)
SHUTDOWN CURRENT (µA)
35
SHUTDOWN CURRENT
vs. INPUT VOLTAGE
6
SHUTDOWN CURRENT (µA)
130
1.50
25
INPUT VOLTAGE (V)
MAX15462 toc12
NO-LOAD SUPPLY CURRENT (µA)
15
5
NO-LOAD SUPPLY CURRENT
vs. TEMPERATURE
140
60
PFM MODE
MAX15462 toc13
-40
98
MAX15462 toc15
FEEDBACK VOLTAGE (V)
0.904
MAX15462 toc11
100
toc10a
0.880
NO-LOAD SUPPLY CURRENT
vs. INPUT VOLTAGE
5
15
25
35
45
55
INPUT VOLTAGE (V)
Maxim Integrated │ 7
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Typical Operating Characteristics (continued)
(VIN = 24V, VGND = 0V, CIN = CVCC = 1µF, VEN/UVLO = 1.5V, TA = +25°C, unless otherwise noted.)
450
400
350
300
SWITCH NEGATIVE CURRENT LIMIT
250
200
-40
-20
20
40
60
80
1.18
1.16
1.14
1.12
FALLING
1.10
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
TEMPERATURE (°C)
SWITCHING FREQUENCY
vs. TEMPERATURE
RESET THRESHOLD
vs. TEMPERATURE
540
520
500
480
460
440
1.20
1.08
100 120
MAX15462 toc18
SWITCHING FREQUENCY (kHz)
560
0
RISING
1.22
98
100 120
MAX15462 toc19
500
MAX15462 toc17
SWITCH PEAK CURRENT LIMIT
EN/UVLO THRESHOLD
vs. TEMPERATURE
1.24
EN/UVLO THRESHOLD VOLTAGE (V)
550
97
RESET THRESHOLD (%)
SWITCH CURRENT LIMIT (mA)
600
MAX15462 toc16
SWITCH CURRENT LIMIT
vs. TEMPERATURE
96
RISING
95
94
93
FALLING
92
91
-40
-20
0
20
40
60
80
100 120
90
0
10
20
30
40
50
60
TEMPERATURE (°C)
TEMPERATURE (°C)
LOAD TRANSIENT RESPONSE,
PFM MODE (LOAD CURRENT STEPPED
FROM 5mA TO 150mA)
LOAD TRANSIENT RESPONSE,
PFM MODE (LOAD CURRENT STEPPED
FROM 5mA TO 150mA)
MAX15462 toc20
MAX15462 toc21
VOUT (AC)
100mV/div
VOUT (AC)
100mV/div
FIGURE 5
APPLICATION CIRCUIT
VOUT = 3.3V
IOUT
100mA/div
IOUT
100mA /div
100µs /div
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FIGURE 6
APPLICATION CIRCUIT
VOUT = 5V
100µs /div
Maxim Integrated │ 8
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Typical Operating Characteristics (continued)
(VIN = 24V, VGND = 0V, CIN = CVCC = 1µF, VEN/UVLO = 1.5V, TA = +25°C, unless otherwise noted.)
LOAD TRANSIENT RESPONSE
PFM MODE (LOAD CURRENT STEPPED
FROM 5mA TO 150mA)
LOAD TRANSIENT RESPONSE,
PFM MODE (LOAD CURRENT STEPPED
FROM 5mA TO 150mA)
toc21b
toc21a
VOUT (AC)
200mV/div
VOUT (AC)
100mV/div
FIGURE 8
APPLICATION CIRCUIT
VOUT = 12V
FIGURE 7
APPLICATION CIRCUIT
VOUT = 2.5V
IOUT
100mA/div
IOUT
100mA/div
100µs/div
100µs/div
LOAD TRANSIENT RESPONSE,
PFM OR PWM MODE (LOAD CURRENT
STEPPED FROM 150mA TO 300mA)
LOAD TRANSIENT RESPONSE,
PFM OR PWM MODE (LOAD CURRENT
STEPPED FROM 150mA TO 300mA)
MAX15062 toc22
MAX15062 toc23
VOUT (AC)
100mV/div
VOUT (AC)
100mV/div
IOUT
100mA /div
IOUT
100mA /div
FIGURE 5
APPLICATION CIRCUIT
VOUT = 3.3V
40µs /div
FIGURE 6
APPLICATION CIRCUIT
VOUT = 5V
40µs/div
LOAD TRANSIENT RESPONSE
PFM OR PWM MODE (LOAD CURRENT
STEPPED FROM 150mA TO 300mA)
LOAD TRANSIENT RESPONSE
PFM OR PWM MODE (LOAD CURRENT
STEPPED FROM 150mA TO 300mA)
toc23b
toc23a
VOUT (AC)
50mV/div
VOUT (AC)
200mV/div
IOUT
100mA/div
IOUT
FIGURE 7
APPLICATION CIRCUIT
VOUT = 2.5V
40µs/div
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100mA/div
FIGURE 8
APPLICATION CIRCUIT
VOUT = 12V
40µs/div
Maxim Integrated │ 9
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Typical Operating Characteristics (continued)
(VIN = 24V, VGND = 0V, CIN = CVCC = 1µF, VEN/UVLO = 1.5V, TA = +25°C, unless otherwise noted.)
LOAD TRANSIENT RESPONSE,
PWM MODE (LOAD CURRENT
STEPPED FROM NO LOAD TO 150mA)
LOAD TRANSIENT RESPONSE,
PWM MODE PWM mode (LOAD CURRENT
STEPPED FROM NO LOAD TO 150mA)
MAX15062 toc24
VOUT (AC)
100mV/div
MAX15062 toc25
VOUT (AC)
100mV/div
FIGURE 5
APPLICATION CIRCUIT
VOUT = 3.3V
FIGURE 6
APPLICATION CIRCUIT
VOUT = 5V
IOUT
100mA /div
IOUT
100mA/div
40µs/div
40µs /div
LOAD TRANSIENT RESPONSE
PWM MODE (LOAD CURRENT STEPPED
FROM NO LOAD TO 150mA)
LOAD TRANSIENT RESPONSE
PWM MODE (LOAD CURRENT STEPPED
FROM NO LOAD TO 150mA)
toc25a
toc25b
VOUT (AC)
VOUT (AC)
200mV/div
50mV/div
FIGURE 8
APPLICATION CIRCUIT
VOUT = 12V
FIGURE 7
APPLICATION CIRCUIT
VOUT = 2.5V
IOUT
100mA/div
IOUT
100mA/div
40µs/div
40µs/div
FULL-LOAD SWITCHING WAVEFORMS
(PWM OR PFM MODE)
SWITCHING WAVEFORMS
(PFM MODE)
MAX15062 toc27
MAX15062 toc26
VOUT (AC)
100mV/div
FIGURE 6 APPLICATION CIRCUIT
VOUT = 5V, LOAD = 20mA
VOUT (AC)
20mV/div
VLX
10V/div
VLX
10V/div
IOUT
100mA/div
IOUT
200mA /div
10µs /div
www.maximintegrated.com
VOUT = 5V,
LOAD = 300mA
2µs/div
Maxim Integrated │ 10
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Typical Operating Characteristics (continued)
(VIN = 24V, VGND = 0V, CIN = CVCC = 1µF, VEN/UVLO = 1.5V, TA = +25°C, unless otherwise noted.)
NO-LOAD SWITCHING WAVEFORMS
(PWM MODE)
SOFT-START
MAX15062 toc28
VOUT = 5V
VOUT (AC)
20mV/div
MAX15062 toc29
VEN/UVLO
5V/div
VOUT
1V/div
VLX
10V/div
IOUT
100mA /div
IOUT
100mA/div
VRESET
5V/div
2µs /div
SOFT-START
FIGURE 5
APPLICATION CIRCUIT
VOUT = 3.3V
1ms/div
SOFT-START
MAX15062 toc30
toc30a
VEN/UVLO
5V/div
VEN/UVLO
5V/div
VOUT
1V/div
VOUT
1V/div
IOUT
100mA /div
VRESET
5V/div
FIGURE 6
APPLICATION CIRCUIT
VOUT = 5V
IOUT
100mA/div
VRESET
5V/div
FIGURE 7
APPLICATION CIRCUIT
VOUT = 2.5V
1ms/div
1ms/div
SHUTDOWN WITH ENABLE
SOFT-START
MAX15062 toc31
toc30b
VEN/UVLO
VEN/UVLO
5V/div
5V/div
VOUT
1V/div
VOUT
5V/div
IOUT
100mA/div
IOUT
100mA /div
FIGURE 8
APPLICATION CIRCUIT
VOUT = 12V
VRESET
5V/div
1ms/div
www.maximintegrated.com
VRESET
5V/div
400µs /div
Maxim Integrated │ 11
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Typical Operating Characteristics (continued)
(VIN = 24V, VGND = 0V, CIN = CVCC = 1µF, VEN/UVLO = 1.5V, TA = +25°C, unless otherwise noted.)
MAX15062 toc33
VEN/UVLO
5V/div
BODE PLOT
50
VIN
20V/div
40
FIGURE 6
APPLICATION CIRCUIT
NO LOAD
PWM MODE
GAIN (dB)
VOUT
2V/div
1ms /div
MAX15062 toc35
108
30
72
20
10
36
10
0
0
PHASE
20
fCR = 47kHz,
PHASE MARGIN = 60°
-10
-20
FIGURE 6 APPLICATION CIRCUIT
VOUT = 5V
-30
-40
-50
-36
2
4 6 81
1k
2
4 6 81
10k
2
100k
GAIN (dB)
40
PHASE (°)
144
GAIN
50
-20
-108
-30
-144
-40
-180
-50
180
72
10
36
0
0
fCR = 36kHz,
PHASE MARGIN = 66°
-36
-72
-20
FIGURE 8 APPLICATION CIRCUIT
VOUT = 12V
-40
-50
1k
10k
FREQUENCY (Hz)
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4 6 81
2
100k
10k
-144
-180
MAX15062 toc35a
180
144
108
72
PHASE
36
0
fCR = 43kHz,
PHASE MARGIN = 60°
-36
-72
FIGURE 7 APPLICATION CIRCUIT
VOUT = 2.5V
1k
10k
-108
-144
-180
100k
70
108
PHASE
-30
1k
2
MAX15462, 5V OUTPUT, 0.3A LOAD CURRENT,
CONDUCTED EMI CURVE toc36
100k
-108
-144
-180
CONDUCTED EMI (dBµV)
GAIN (dB)
MAX15062 toc35b
144
20
-10
4 6 81
-108
FREQUENCY (Hz)
GAIN
30
2
GAIN
-10
-72
PHASE (°)
40
-72
FIGURE 5 APPLICATION CIRCUIT
VOUT = 3.3V
BODE PLOT
0
FREQUENCY (Hz)
BODE PLOT
-36
FREQUENCY (Hz)
50
30
GAIN (dB)
-50
0
fCR = 47kHz,
PHASE MARGIN = 59°
-10
-40
180
40
36
0
20ms /div
BODE PLOT
50
72
10
-30
IOUT
200mA /div
108
PHASE
-20
VRESET
5V/div
180
144
GAIN
30
20
VOUT
1V/div
MAX15062 toc34
PHASE (°)
OVERLOAD PROTECTION
MAX15062 toc32
PHASE (°)
SOFT-START WITH 3V PREBIAS
60
50
QUASI-PEAK LIMIT
AVERAGE LIMIT
40
30
PEAK
EMISSIONS
20
AVERAGE
EMISSIONS
10
0.15
1
10
FREQUENCY (MHz)
30
Maxim Integrated │ 12
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Pin Configuration
TOP VIEW
LX
GND
RESET
MODE
8
7
6
5
MAX15462
+
1
2
3
4
VIN
EN/UVLO
VCC
FB/VOUT
TDFN
(2mm x 2mm)
Pin Description
PIN
NAME
FUNCTION
1
VIN
Switching Regulator Power Input. Connect a X7R 1µF ceramic capacitor from VIN to GND for bypassing.
2
EN/UVLO
3
VCC
4
FB/VOUT
5
MODE
PFM/PWM Mode Selection Input. Connect MODE to GND to enable the fixed-frequency PWM
operation. Leave unconnected for light-load PFM operation.
6
RESET
Open-Drain Reset Output. Pull up RESET to an external power supply with an external resistor.
RESET goes low when the output voltage drops below 92% of the set nominal regulated voltage.
RESET goes high impedance 2ms after the output voltage rises above 95% of its regulation value. See
the Electrical Characteristics table for threshold values.
7
GND
8
LX
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Active-High, Enable/Undervoltage-Detection Input. Pull EN/UVLO to GND to disable the regulator
output. Connect EN/UVLO to VIN for always-on operation. Connect a resistor-divider between VIN and
EN/UVLO to GND to program the input voltage at which the device is enabled and turns on.
Internal LDO Power Output. Bypass VCC to GND with a minimum 1µF capacitor.
Feedback Input. For fixed-output voltage versions, connect FB/VOUT directly to the output. For the
adjustable output voltage version, connect FB/VOUT to a resistor-divider between VOUT and GND to
adjust the output voltage from 0.9V to 0.89 x VIN.
Ground. Connect GND to the power ground plane. Connect all the circuit ground connections together at
a single point. See the PCB Layout Guidelines section.
Inductor Connection. Connect LX to the switching-side of the inductor. LX is high impedance when the
device is in shutdown.
Maxim Integrated │ 13
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Block Diagram
VIN
LDO
REGULATOR
PEAK-LIMIT
RUNAWAYCURRENTLIMIT
SENSE
LOGIC
PFM
VCC
MAX15462
CS
CURRENTSENSE
AMPLIFIER
POK
EN/UVLO
DH
CHIPEN
HIGH-SIDE
DRIVER
1.215V
THERMAL
SHUTDOWN
VCC
CLK
LX
OSCILLATOR
SLOPE
500kΩ
MODE
MODE SELECT
0.55VCC
PFM/PWM
CONTROL
LOGIC
DL
LOW-SIDE
DRIVER
SLOPE
CS
FB/VOUT
R1
*
PWM
SINK-LIMIT
ERROR
AMPLIFIER
R2
REFERENCE
SOFT-START
CLK
*RESISTOR-DIVIDER ONLY FOR MAX15462A, MAX15462B
www.maximintegrated.com
LOW-SIDE
CURRENT
SENSE
NEGATIVE
CURRENT
REF
3.135V FOR MAX15462A
4.75V FOR MAX15462B
0.859V FOR MAX15462C
FB/VOUT
GND
RESET
2ms
DELAY
Maxim Integrated │ 14
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Detailed Description
The MAX15462 high-efficiency, high-voltage, synchronous
step-down DC-DC converter with integrated MOSFETs
operates over a wide 4.5V to 42V input voltage range.
The converter delivers output current up to 300mA at
3.3V (MAX15462A), 5V (MAX15462B), and adjustable
output voltages (MAX15462C). When EN/UVLO and
VCC UVLO are satisfied, an internal power-up sequence
soft-starts the error-amplifier reference, resulting in a
clean monotonic output-voltage soft-start independent of
the load current. The FB/VOUT pin monitors the output
voltage through a resistor-divider. RESET transitions
to a high-impedance state 2ms after the output voltage
reaches 95% of regulation. The device selects either
PFM or forced-PWM mode depending on the state of the
MODE pin at power-up. By pulling the EN/UVLO pin low,
the device enters the shutdown mode and consumes only
2.2µA (typ) of standby current.
DC-DC Switching Regulator
The device uses an internally compensated, fixed-frequency,
current-mode control scheme (see the Block Diagram).
On the rising-edge of an internal clock, the high-side
pMOSFET turns on. An internal error amplifier compares
the feedback voltage to a fixed internal reference voltage
and generates an error voltage. The error voltage is compared to a sum of the current-sense voltage and a slopecompensation voltage by a PWM comparator to set the
on-time. During the on-time of the pMOSFET, the inductor current ramps up. For the remainder of the switching
period (off-time), the pMOSFET is kept off and the lowside nMOSFET turns on. During the off-time, the inductor
releases the stored energy as the inductor current ramps
down, providing current to the output. Under overload
conditions, the cycle-by-cycle current-limit feature limits
the inductor peak current by turning off the high-side
pMOSFET and turning on the low-side nMOSFET.
Mode Selection (MODE)
The logic state of the MODE pin is latched after VCC
and EN/UVLO voltages exceed respective UVLO rising
thresholds and all internal voltages are ready to allow
LX switching. If the MODE pin is unconnected at powerup, the part operates in PFM mode at light loads. If the
MODE pin is grounded at power-up, the part operates in
constant-frequency PWM mode at all loads. State changes
on the MODE pin are ignored during normal operation.
loads. However, the PWM mode of operation gives lower
efficiency at light loads compared to PFM mode of operation.
PFM Mode Operation
PFM mode operation disables negative inductor current
and skips pulses at light loads for high efficiency. In
PFM mode, the inductor current is forced to a fixed
peak of 130mA every clock cycle until the output rises to
102.3% of the nominal voltage. Once the output reaches
102.3% of the nominal voltage, both high-side and lowside FETs are turned off and the part enters hibernate
operation until the load discharges the output to 101.1%
of the nominal voltage. Most of the internal blocks are
turned off in hibernate operation to save quiescent current. After the output falls below 101.1% of the nominal
voltage, the device comes out of hibernate operation,
turns on all internal blocks, and again commences the
process of delivering pulses of energy to the output until
it reaches 102.3% of the nominal output voltage. The device
naturally exits PFM mode when the load current exceeds
55mA (typ). The advantage of the PFM mode is higher
efficiency at light loads because of lower quiescent
current drawn from supply.
Internal 5V Linear Regulator
An internal regulator provides a 5V nominal supply to
power the internal functions and to drive the power
MOSFETs. The output of the linear regulator (VCC) should
be bypassed with a 1µF capacitor to GND. The VCC
regulator dropout voltage is typically 150mV. An undervoltage-lockout circuit that disables the regulator when VCC
falls below 3.8V (typ). The 400mV VCC UVLO hysteresis
prevents chattering on power-up and power-down.
Enable Input (EN/UVLO), Soft-Start
When EN/UVLO voltage is above 1.21V (typ), the device’s
internal error-amplifier reference voltage starts to ramp up.
The duration of the soft-start ramp is 4.1ms, allowing a
smooth increase of the output voltage. Driving EN/UVLO
low disables both power MOSFETs, as well as other internal
circuitry, and reduces VIN quiescent current to below 2.2µA.
EN/UVLO can be used as an input-voltage UVLO adjustment
input. An external voltage-divider between VIN and EN/UVLO
to GND adjusts the input voltage at which the device turns
on or turns off. If input UVLO programming is not desired,
connect EN/UVLO to VIN (see the Electrical Characteristics
table for EN/UVLO rising and falling threshold voltages).
PWM Mode Operation
In PWM mode, the inductor current is allowed to go
negative. PWM operation is useful in frequency-sensitive
applications, providing fixed switching frequency at all
www.maximintegrated.com
Maxim Integrated │ 15
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Reset Output (RESET)
The device includes an open-drain RESET output to
monitor the output voltage. RESET goes high impedance
2ms after the output rises above 95% of its nominal set
value and pulls low when the output voltage falls below
92% of the set nominal regulated voltage. RESET asserts
low during the hiccup timeout period.
Startup into a Prebiased Output
The device is capable of soft-start into a prebiased
output, without discharging the output capacitor in both the
PFM and forced-PWM modes. Such a feature is useful in
applications where digital integrated circuits with multiple
rails are powered.
Operating Input Voltage Range
The maximum operating input voltage is determined
by the minimum controllable on-time and the minimum
operating input voltage is determined by the maximum
duty cycle and circuit voltage drops. The minimum and
maximum operating input voltages for a given output
voltage should be calculated as follows:
VINMIN
VOUT + (I OUT × (R DCR + 0.5))
+ (I OUT × 1.0)
D MAX
VINMAX =
VOUT
t ONMIN × f SW
where VOUT is the steady-state output voltage, IOUT is
the maximum load current, RDCR is the DC resistance of
the inductor, fSW is the switching frequency (max), DMAX
is maximum duty cycle (0.9), and tONMIN is the worstcase minimum controllable switch on-time (130ns).
Overcurrent Protection/Hiccup Mode
The device is provided with a robust overcurrent protection scheme that protects the device under overload and
output short-circuit conditions. A cycle-by-cycle peak
current limit turns off the high-side MOSFET whenever
the high-side switch current exceeds an internal limit
of 0.56A (typ). A runaway current limit on the high-side
switch current at 0.66A (typ) protects the device under
high input voltage, and short-circuit conditions when
there is insufficient output voltage available to restore the
inductor current that was built up during the on period of
the step-down converter. One occurrence of the runaway
current limit triggers a hiccup mode. In addition, if, due to
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a fault condition, the output voltage drops to 65% (typ)
of its nominal value any time after soft-start is complete,
hiccup mode is triggered. In hiccup mode, the converter
is protected by suspending switching for a hiccup timeout
period of 131ms. Once the hiccup timeout period expires,
soft-start is attempted again. Hiccup mode of operation
ensures low power dissipation under output short-circuit
conditions.
Care should be taken in board layout and system wiring
to prevent violation of the absolute maximum rating of the
FB/VOUT pin under short-circuit conditions. Under such
conditions, it is possible for the ceramic output capacitor
to oscillate with the board or wiring inductance between
the output capacitor or short-circuited load, thereby causing
the absolute maximum rating of FB/VOUT (-0.3V) to be
exceeded. The parasitic board or wiring inductance should
be minimized, and the output voltage waveform under
short-circuit operation should be verified, to ensure the
absolute maximum rating of FB/VOUT is not exceeded.
Thermal Overload Protection
Thermal overload protection limits the total power
dissipation in the device. When the junction temperature
exceeds +166°C, an on-chip thermal sensor shuts down
the device, turns off the internal power MOSFETs, allowing
the device to cool down. The thermal sensor turns the
device on after the junction temperature cools by 10°C.
Applications Information
Inductor Selection
A low-loss inductor having the lowest possible DC
resistance that fits in the allotted dimensions should be
selected. The saturation current (ISAT) must be high
enough to ensure that saturation cannot occur below the
maximum current-limit value (IPEAK-LIMIT) of 0.56A (typ).
The required inductance for a given application can be
determined from the following equation:
L = 9.3 x VOUT
where L is inductance in µH and VOUT is output voltage.
Once the L value is known, the next step is to select the
right core material. Ferrite and powdered iron are commonly available core materials. Ferrite cores have low
core losses and are preferred for high-efficiency designs.
Powdered iron cores have more core losses and are relatively cheaper than ferrite cores. See Table 1 to select the
inductors for typical applications.
Maxim Integrated │ 16
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Table 1. Inductor Selection
INPUT VOLTAGE
RANGE VIN (V)
VOUT (V)
4.5 to 42
3.3
300
33
Coilcraft LPS4018-333ML
6 to 42
5
300
47
Coilcraft LPS4018-473ML
4.5 to 42
1.8 or 2.5
300
22
Coilcraft LPS4018-223ML
IOUT (mA)
L (µH)
RECOMMENDED PART NO.
14 to 42
12
300
100
Wurth 74408943101
17 to 42
15
300
150
TDK VLC6045T-151M
Table 2. Output Capacitor Selection
INPUT VOLTAGE
RANGE VIN (V)
VOUT (V)
IOUT (mA)
COUT (µF)
4.5 to 42
3.3
300
10µF/1206/X7R/6.3V
Murata GRM31CR70J106K
RECOMMENDED PART NO.
6 to 42
5
300
10µF/1206/X7R/6.3V
Murata GRM31CR70J106K
4.5 to 42
1.8 or 2.5
300
22µF/1206/X7R/6.3V
Murata GRM31CR70J226K
14 to 42
12
300
4.7µF/1206/X7R/16V
Murata GRM31CR71C475K
17 to 42
15
300
4.7µF/1206/X7R/25V
Murata GRM31CR71E475K
VIN
VIN
R1
MAX15462
EN/UVLO
R2
Figure 1. Adjustable EN/UVLO Network
Input Capacitor
Small ceramic capacitors are recommended for the
device. The input capacitor reduces peak current drawn
from the power source and reduces noise and voltage
ripple on the input caused by the switching circuitry. A
minimum of 1µF, X7R-grade capacitor is recommended
for the input capacitor of the device to keep the input
voltage ripple under 2% of the minimum input voltage,
and to meet the maximum ripple-current requirements.
Output Capacitor
Small ceramic X7R-grade capacitors are sufficient and
recommended for the device. The output capacitor has
two functions. It filters the square wave generated by the
device along with the output inductor. It stores sufficient
energy to support the output voltage under load transient
conditions and stabilizes the device’s internal control
loop. Usually, the output capacitor is sized to support a
step load of 50% of the maximum output current in the
www.maximintegrated.com
application, such that the output-voltage deviation is less
than 3%. Required output capacitance can be calculated
from the following equation:
C OUT =
30
VOUT
where COUT is the output capacitance in µF and VOUT
is the output voltage. See Table 2 to select the output
capacitor for typical applications. It should be noted that
dielectric materials used in ceramic capacitors exhibit
capacitance loss due to DC bias levels and should be
appropriately derated to ensure the required output
capacitance is obtained in the application.
Setting the Input Undervoltage-Lockout Level
The devices offer an adjustable input undervoltagelockout level. Set the voltage at which the device turns
on with a resistive voltage-divider connected from VIN
to GND (see Figure 1). Connect the center node of the
divider to EN/UVLO.
Choose R1 to be 3.3MΩ max, and then calculate R2 as follows:
R2 =
R1× 1.215
(VINU - 1.215)
where VINU is the voltage at which the device is required
to turn on. If the EN/UVLO pin is driven from an external
signal source, a series resistance of minimum 1kΩ is
recommended to be placed between the signal source
output and the EN/UVLO pin, to reduce voltage ringing
on the line.
Maxim Integrated │ 17
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Adjusting the Output Voltage
PCB Layout Guidelines
For output voltages less than 6V, choose R2 in the 50kΩ
to 150kΩ range. For the output voltages greater than 6V,
choose R2 in the 25kΩ to 75kΩ range and calculate R1
with the following equation:
● Place the input ceramic capacitor as close as possible
to the VIN and GND pins.
The MAX15462C output voltage can be programmed from
0.9V to 0.89 x VIN. Set the output voltage by connecting a
resistor-divider from output to FB to GND (see Figure 2).
V
= R2 × OUT
R1
0.9
−
1
Power Dissipation
At a particular operating condition, the power losses that
lead to temperature rise of the part are estimated as follows:
1
2
PLOSS =
POUT × - 1 - (I OUT × R DCR )
η
P=
OUT VOUT × I OUT
Careful PCB layout is critical to achieve clean and stable
operation. The switching power stage requires particular
attention. Follow the guidelines below for good PCB layout.
● Connect the negative terminal of the VCC bypass
capacitor to the GND pin with shortest possible trace or
ground plane.
● Minimize the area formed by the LX pin and the inductor
connection to reduce the radiated EMI.
● Place the VCC decoupling capacitor as close as possible
to the VCC pin.
● Ensure that all feedback connections are short and
direct.
● Route the high-speed switching node (LX) away from
the FB/VOUT, RESET, and MODE pins.
For a sample PCB layout that ensures the first-pass
success, refer to the MAX15462 evaluation kit layouts
available at www.maximintegrated.com.
where POUT is the output power, η is the efficiency of
power conversion, and RDCR is the DC resistance of the
output inductor. See the Typical Operating Characteristics
for the power-conversion efficiency or measure the
efficiency to determine the total power dissipation.
The junction temperature (TJ) of the device can be
estimated at any ambient temperature (TA) from the
following equation:
TJ= T A + (θ JA × PLOSS )
where θJA is the junction-to-ambient thermal impedance
of the package. Junction temperature greater than +125°C
degrades operating lifetimes.
www.maximintegrated.com
VOUT
R1
FB
MAX15462C
R2
GND
Figure 2. Setting the Output Voltage
Maxim Integrated │ 18
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
VIN
VIN
CIN
LX
L1
VOUT
COUT
R1
GND
EN/UVLO
MAX15462A/B
R2
VOUT
VCC
VCC
CVCC
RESET
R3
MODE
VCC
VIN PLANE
CIN
U1
R1
LX
VIN
EN/UVLO
GND
VCC
R2
CVCC
L1
COUT
RESET
VOUT
MODE
R3
VIAS TO BOTTOM-SIDE GROUND PLANE
VIAS TO VOUT
GND
PLANE
VOUT PLANE
VIAS TO VCC
Figure 3. Layout Guidelines for MAX15462A and MAX15462B
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Maxim Integrated │ 19
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
VIN
VIN
CIN
LX
L1
VOUT
COUT
R1
GND
EN/UVLO
R4
MAX15462C
R2
FB
VCC
R5
VCC
CVCC
RESET
R3
MODE
VCC
VIN PLANE
CIN
U1
R1
LX
VIN
EN/UVLO
GND
VCC
R2
CVCC
L1
COUT
RESET
FB
MODE
GND
PLANE
R5
VOUT PLANE
R4
R3
VIAS TO BOTTOM-SIDE GROUND PLANE
VIAS TO VOUT
VIAS TO VCC
Figure 4. Layout Guidelines for MAX15462C
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Maxim Integrated │ 20
MAX15462
VIN
4.5V TO
42V
CIN
1µF
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
VIN
EN/UVLO
LX
L1
33µH
COUT
10µF
GND
VOUT
3.3V,
300mA
VIN
6V TO
42V
CIN
1µF
MAX15462A
CVCC
1µF
VCC
MODE
EN/UVLO
LX
COUT
10µF
GND
RESET
CVCC
1µF
VOUT
VCC
MODE
RESET
VOUT
MODE = GND FOR PWM
MODE = OPEN FOR PFM
MODE = GND FOR PWM
MODE = OPEN FOR PFM
L1: COILCRAFT LPS4018-333ML
COUT: MURATA 10µF/X7R/6.3V/1206 GRM31CR70J106K
CIN: MURATA 1μF/X7R/50V/1206 GRM31CR71H105K
L1: COILCRAFT LPS4018-473ML
COUT: MURATA 10µF/X7R/6.3V/1206 GRM31CR70J106K
CIN: MURATA 1μF/X7R/50V/1206 GRM31CR71H105K
CIN
1µF
VIN
EN/UVLO
LX
VCC
MODE
Figure 6. 5V, 300mA Step-Down Regulator
L1
22µH
GND
MAX15462C
CVCC
1µF
COUT
22µF
VOUT
2.5V,
300mA
CIN
1µF
R1
133kΩ
FB
RESET
VIN
14V TO
42V
EN/UVLO
LX
COUT
4.7µF
GND
VCC
MODE
FB
R2
40.2kΩ
RESET
MODE = GND FOR PWM
MODE = OPEN FOR PFM
L1: COILCRAFT LPS4018-223ML
COUT: MURATA 22µF/X7R/6.3V/1206 (GRM31CR70J226K)
CIN: M URATA 1μF/X7R/50V/1206 (GRM31CR71H105K)
L1: Wurth 74408943101
COUT: MURATA 4.7µF/X7R/16V/1206 (GRM31CR71C475K)
CIN: M URATA 1μF/X7R/50V/1206 (GRM31CR71H105K)
Figure 7. 2.5V, 300mA Step-Down Regulator
VOUT
12V,
300mA
R1
499kΩ
MAX15462C
CVCC
1µF
R2
75kΩ
VIN
L1
100µH
MODE = GND FOR PWM
MODE = OPEN FOR PFM
www.maximintegrated.com
VOUT
5V,
300mA
MAX15462B
Figure 5. 3.3V, 300mA Step-Down Regulator
VIN
4.5V TO
42V
VIN
L1
47µH
Figure 8. 12V, 300mA Step-Down Regulator
Maxim Integrated │ 21
MAX15462
VIN
4.5V TO
42V
CIN
1µF
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
VIN
LX
EN/UVLO
L1
22µH
COUT
22µF
GND
FB
VCC
MODE
VIN
17V TO
42V
CIN
1µF
R1
75kΩ
MAX15462C
CVCC
1µF
VOUT
1.8V,
300mA
EN/UVLO
LX
COUT
4.7µF
GND
R2
75kΩ
FB
VCC
MODE
R2
31.6kΩ
RESET
MODE = GND FOR PWM
MODE = OPEN FOR PFM
MODE = GND FOR PWM
MODE = OPEN FOR PFM
L1: COILCRAFT LPS4018-223ML
COUT: MURATA 22µF/X7R/6.3V/1206 (GRM31CR70J226K)
CIN: MURATA 1μF/X7R/50V/1206 (GRM31CR71H105K)
L1: TDK VLC6045T-151M
COUT: MURATA 4.7µF/X7R/25V/1206 (GRM31CR71E475K)
CIN: MURATA 1μF/X7R/50V/1206 (GRM31CR71H105K)
Figure 9. 1.8V, 300mA Step-Down Regulator
Figure 10. 15V, 300mA Step-Down Regulator
Ordering Information
Package Information
PART
TEMP RANGE
PINPACKAGE
VOUT
MAX15462AATA+
-40°C to +125°C
8 TDFN
3.3V
MAX15462BATA+
-40°C to +125°C
8 TDFN
5V
MAX15462CATA+
-40°C to +125°C
8 TDFN
Adj
+Denotes a lead(Pb)-free/RoHS-compliant package.
VOUT
15V,
300mA
R1
499kΩ
MAX15462C
CVCC
1µF
RESET
VIN
L1
150µH
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 TDFN
T822CN+1
21-0487
90-0349
Chip Information
PROCESS: BiCMOS
www.maximintegrated.com
Maxim Integrated │ 22
MAX15462
42V, 300mA, Ultra-Small, High-Efficiency,
Synchronous Step-Down DC-DC Converters
Revision History
REVISION
NUMBER
REVISION
DATE
0
3/15
Initial release
1
2/17
Updated junction temperature and added text TOC36
DESCRIPTION
PAGES
CHANGED
—
1–4, 12, 17, 18
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.
© 2017 Maxim Integrated Products, Inc. │ 23
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