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MAX1836EUT50-T ,24V Internal Switch / 100% Duty Cycle / Step-Down ConvertersELECTRICAL CHARACTERISTICS(Circuits of Figures 1 (MAX1836) and 2 (MAX1837), V = 12V, SHDN = IN, T = ..
MAX1837 ,24V Internal Switch, 100% Duty Cycle, Step-Down ConvertersApplicationsMAX1837ETT50-T -40°C to +85°C 6 TDFN-EP* AJF● 9V Battery SystemsMAX1837EUT33-T -40°C to ..
MAX1837ETT33+T ,24V Internal Switch, 100% Duty Cycle, Step-Down ConvertersElectrical Characteristics (continued)(Circuits of Figures 1 (MAX1836) and 2 (MAX1837), V = 12V, SH ..
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MAX1836ETT33+T-MAX1836EUT33+T-MAX1836EUT50+T-MAX1837ETT33+T-MAX1837EUT33#TG16-MAX1837EUT33+T
24V Internal Switch, 100% Duty Cycle, Step-Down Converters
General DescriptionThe MAX1836/MAX1837 high-efficiency step-down con-
verters provide a preset 3.3V or 5V output voltage from
supply voltages as high as 24V. Using external feedback
resistors, the output voltage can be adjusted from 1.25V
to VIN. An internal current-limited switching MOSFET
delivers load currents up to 125mA (MAX1836) or 250mA
(MAX1837).
The unique current-limited control scheme, operating
with duty cycles up to 100%, minimizes the dropout volt-
age (120mV at 100mA). Additionally, this control scheme reduces supply current under light loads to 12μA. High
switching frequencies allow the use of tiny surface-mount
inductors and output capacitors.
The MAX1836/MAX1837 step-down converters with inter-
nal switching MOSFETs are available in 6-pin SOT23
and 3mm x 3mm TDFN packages, making them ideal
for low-cost, low-power, space-sensitive applications.
For increased output drive capability, use the MAX1776
step-down converter that uses an internal 24V switch to
deliver up to 500mA. For even higher currents, use the
MAX1626/MAX1627 step-down controllers that drive an
external P-channel MOSFET to deliver up to 20W.
Applications●9V Battery Systems●Notebook Computers●Distributed Power Systems●Backup Supplies●4mA to 20mA Loop Power Supplies●Industrial Control Supplies●Handheld Devices
Features●4.5V to 24V Input Voltage Range●Preset 3.3V or 5V Output●Adjustable Output from 1.25V to VIN●Output Currents Up to 125mA (MAX1836) or
250mA (MAX1837)●Efficiency Over 90%●12μA Quiescent Current●3μA Shutdown Current●100% Maximum Duty Cycle for Low Dropout●Small 6-Pin SOT23 and TDFN Packages
Selector Guide appears at end of data sheet.*EP = Exposed pad.
T = Tape and reel.
PARTTEMP RANGEPIN-
PACKAGE
TOP
MARK
MAX1836ETT33-T-40°C to +85°C6 TDFN-EP*AJG
MAX1836ETT50-T-40°C to +85°C6 TDFN-EP*AJE
MAX1836EUT33-T-40°C to +85°C6 SOT23AANY
MAX1836EUT50-T-40°C to +85°C6 SOT23AANW
MAX1837ETT33-T-40°C to +85°C6 TDFN-EP*AJH
MAX1837ETT50-T-40°C to +85°C6 TDFN-EP*AJF
MAX1837EUT33-T-40°C to +85°C6 SOT23AANZ
MAX1837EUT50-T-40°C to +85°C6 SOT23AANX
MAX1836
MAX1837GND
SHDN
OUT
NOTE: HIGH-CURRENT PATHS SHOWN WITH BOLD LINES.OUTPUT
3.3V OR 5V
INPUT
4.5V TO 24V
GNDIN6OUTSHDN
MAX1836
MAX1837
MAX1836
MAX1837
SOT23
TDFNTOP VIEW
GNDFBOUTSHDN
MAX1836/MAX183724V Internal Switch, 100% Duty Cycle,
Step-Down Converters
Typical Operating CircuitPin Conigurations
Ordering Information
EVALUATION KIT AVAILABLE
IN, SHDN to GND...................................................-0.3V to +25V
LX to GND.......................................................-2V to (VIN + 0.3V)
OUT, FB to GND.......................................................-0.3V to +6V
Continuous Power Dissipation (TA = +70°C) (Note 1)
6-Pin SOT23 (derate 8.7mW/°C above +70°C)...........696mW
6-Pin TDFN (derate 24.4mW/°C above +70°C).........1951mW
Operating Temperature Range..............................-40°C to +85°C
Junction Temperature.......................................................+150°C
Storage Temperature Range...............................-65°C to +150°C
Lead Temperature (soldering, 10s)...................................+300°C
(Circuits of Figures 1 (MAX1836) and 2 (MAX1837), VIN = 12V, SHDN = IN, TA = 0°C to +85°C. Typical values are at TA = +25°C,
unless otherwise noted.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSInput Supply RangeVIN4.524V
Input Undervoltage Lockout
ThresholdVUVLO
VIN rising3.554.04.4VIN falling3.453.94.3
Input Supply CurrentIIN1225µA
Input Supply Current in DropoutIIN(DROP)VIN = 5V18µA
Input Shutdown CurrentSHDN = GND37µA
Output Voltage (Preset Mode)VOUT
FB = GND,
ILOAD = 0 to 125mA
(MAX1836) or
250mA (MAX1837)
MAX183_EUT50,
MAX183_ETT504.805.005.20
MAX183_EUT33,
MAX183_ETT333.1683.303.432
Output Voltage Range
(Adjustable Mode)VOUT(Note 2)1.25VINV
Feedback Set Voltage
(Adjustable Mode)VFB1.2001.251.300V
OUT Bias Current VOUT = 5V2.57.4µA
FB Bias CurrentIFBVFB = 0 or 1.25V, TA = +25°C-25+25nA
FB Dual ModeTM ThresholdVFB rising or falling50100150mV
LX Switch Minimum Off-TimetOFF(MIN)0.20.40.6µs
LX Switch Maximum On-TimetON(MAX)VFB = 1.3V71013µs
LX Switch On-ResistanceRLXVIN = 6V1.12Ω
LX Current LimitILIM
MAX1836250312450MAX1837500625850
LX Zero-Crossing Threshold-75+75mV
MAX1836/MAX183724V Internal Switch, 100% Duty Cycle,
Step-Down Converters
Note 1: Thermal properties are specified with product mounted on PC board with 1in2 of copper area and still air.
Absolute Maximum RatingsStresses 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
(Circuits of Figures 1 (MAX1836) and 2 (MAX1837), VIN = 12V, SHDN = IN, TA = -40°C to +85°C, unless otherwise noted.) (Note 4)
(Circuits of Figures 1 (MAX1836) and 2 (MAX1837), VIN = 12V, SHDN = IN, TA = 0°C to +85°C. Typical values are at TA = +25°C,
unless otherwise noted.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSZero-Crossing TimeoutLX does not rise above the threshold30µs
LX Switch Leakage CurrentVIN = 18V, LX = GND, TA = +25°C1µA
Dropout VoltageVDROPOUTIOUT = 100mA, VIN = 5V120mV
Line RegulationVIN = 5V to 24V0.05%
Load RegulationIOUT = 0 to 125mA (MAX1836) or 250mA
(MAX1837)0.3%
Shutdown Input ThresholdVSHDNVIN = 4.5V to 24V (Note 3)0.82.4V
Shutdown Leakage CurrentISHDNVSHDN = 0 or 24V-1+1µA
Thermal Shutdown10°C hysteresis (typ)160°C
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSInput Supply RangeVIN4.524V
Input Undervoltage Lockout
ThresholdVUVLOVIN rising3.554.4VVIN falling3.454.3
Input Supply CurrentIIN25µA
Input Shutdown CurrentSHDN = GND7µA
Output Voltage (Preset Mode)VOUT
FB = GND,
ILOAD = 0 to 125mA
(MAX1836) or
250mA (MAX1837)
MAX183_EUT50,
MAX183_ETT504.805.20
MAX183_EUT33,
MAX183_ETT333.1683.432
Output Voltage Range
(Adjustable Mode)VOUT(Note 2)1.25VINV
Feedback Set Voltage
(Adjustable Mode)VFB1.2001.300V
OUT Bias Current VOUT = 5V7.4µA
FB Dual Mode ThresholdVFB rising or falling50150mV
LX Switch Minimum Off-TimetOFF(MIN)0.20.6µs
LX Switch Maximum On-TimetON(MAX)VFB = 1.3V713µs
LX Switch On-ResistanceRLXVIN = 6V2
ΩLX Current LimitILIMMAX1836250450mAMAX1837500900
MAX1836/MAX183724V Internal Switch, 100% Duty Cycle,
Step-Down Converters
Electrical Characteristics
Electrical Characteristics (continued)
(Circuits of Figures 1 (MAX1836) and 2 (MAX1837), VIN = 12V, SHDN = IN, TA = -40°C to +85°C, unless otherwise noted.) (Note 4)
Note 2: When using the shutdown input, the maximum output voltage allowed with external feedback is 5.5V. If the output voltage is
set above 5.5V, connect shutdown to the input.
Note 3: Shutdown input minimum slew rate (rising or falling) is 10V/ms.
Note 4: Specifications to -40°C are guaranteed by design, not production tested.
(Circuits of Figures 1 (MAX1836) and 2 (MAX1837), VIN = 12V, SHDN = IN, TA = +25°C.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSLX Zero-Crossing Threshold-75+75mV
Shutdown Input ThresholdVSHDNVIN = 4.5V to 24V (Note 3)0.82.4V
Shutdown Leakage CurrentISHDNVSHDN = 0 or 24V-1+1µA
MAX1836EUT33
EFFICIENCY vs. LOAD CURRENT
MAX1836/7 toc02
LOAD CURRENT (mA)
EFFICIENCY (%)
VIN = 9V
VIN = 12V
VIN = 5V
FIGURE 1
VOUT = 3.3V
MAX1837EUT33
OUTPUT VOLTAGE vs. LOAD CURRENT
MAX1836/7 toc03
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
VIN = 9VVIN = 5V
VIN = 12V
FIGURE 2
MAX1837EUT33
EFFICIENCY vs. LOAD CURRENT
MAX1836/7 toc04
LOAD CURRENT (mA)
EFFICIENCY (%)
VIN = 9V
VIN = 12V
VIN = 5V
FIGURE 2
VOUT = 3.3V
MAX1837EUT33
SWITCHING FREQUENCY vs. LOAD CURRENT
MAX1836/7 toc05
LOAD CURRENT (mA)
FREQUENCY (kHz)
VIN = 9V
VIN = 5V
VIN = 12V
FIGURE 2
VOUT = 3.3V
MAX1837EUT33
OUTPUT VOLTAGE vs. INPUT VOLTAGE
MAX1836/7 toc06
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
IOUT = 10mA
IOUT = 200mA
FIGURE 2
VOUT = 3.3V
L1 = 47µH
MAX1836EUT33
OUTPUT VOLTAGE vs. LOAD CURRENT
MAX1836/7 toc01
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
VIN = 5V
VIN = 9V to 12V
FIGURE 1
MAX1836/MAX183724V Internal Switch, 100% Duty Cycle,
Step-Down Converters
Electrical Characteristics (continued)
Typical Operating Characteristics
(Circuits of Figures 1 (MAX1836) and 2 (MAX1837), VIN = 12V, SHDN = IN, TA = +25°C.)
MAX1837EUT33
EFFICIENCY vs. INPUT VOLTAGE
MAX1836/7 toc07
INPUT VOLTAGE (V)
EFFICIENCY (%)
IOUT = 10mA
IOUT = 200mA
FIGURE 2
VOUT = 3.3V
L1 = 47µH
INPUT VOLTAGE (V)
FREQUENCY (kHz)
MAX1837EUT33
SWITCHING FREQUENCY vs. INPUT VOLTAGE2420
MAX1836/7 toc08
IOUT = 200mA
IOUT = 10mA
FIGURE 2
VOUT = 3.3V
L1 = 47µH
MAX1837EUT33
PEAK INDUCTOR CURRENT vs. INPUT VOLTAGE
MAX1836/7 toc09
INPUT VOLTAGE (V)
PEAK INDUCTOR CURRENT (mA)
IOUT = 10mA
IOUT = 200mA
FIGURE 2
VOUT = 3.3V
L1 = 47µH
LIMITED BY
tON(MIN)
LIMITED BY
ILIM
MAX1837EUT50
OUTPUT VOLTAGE vs. LOAD CURRENT
MAX1836/7 toc10
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
VIN = 12V TO 24V
VIN = 7V
VIN = 9V
FIGURE 6
MAX1837EUT50
EFFICIENCY vs. LOAD CURRENT
MAX1836/7 toc11
LOAD CURRENT (mA)
EFFICIENCY (%)
VIN = 9V
VIN = 24VVIN = 18V
VIN = 7V
FIGURE 6
VOUT = 5V
VIN = 12V
MAX1837EUT50
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX1836/7 toc12
DROPOUT VOLTAGE (mV)
FIGURE 6
VOUT = 5V4812162024
NO-LOAD SUPPLY CURRENT
vs. INPUT VOLTAGEMAX1836/7 toc13
SUPPLY CURRENT (µA)
MAX1836/MAX183724V Internal Switch, 100% Duty Cycle,
Step-Down Converters
Typical Operating Characteristics (continued)
