MAX1836 Datasheet, PDF (1/13 Pages) Maxim Integrated Products – 24V Internal Switch, 100% Duty Cycle, Step-Down Converters

19-1919; Rev 1; 01/02
24V Internal Switch, 100% Duty Cycle,
Step-Down Converters
General Description
The MAX1836/MAX1837 high-efficiency step-down
converters provide a preset 3.3V or 5V output voltage
from supply voltages as high as 24V. Using external
feedback resistors, the output voltage may be adjusted
from 1.25V to V_IN. 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
voltage (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
internal switching MOSFETs are available in a 6-pin
SOT23 package, making them ideal for low-cost, low-
power, space-sensitive applications. For increased out-
put 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
Hand-Held Devices
INPUT
4.5V TO 24V
Typical Operating Circuit
IN
LX
SHDN
OUT
MAX1836
MAX1837
GND
FB
OUTPUT
3.3V OR 5V
____________________________Features
o 4.5V to 24V Input Voltage Range
o Preset 3.3V or 5V Output
o Adjustable Output from 1.25V to V_IN
o Output Currents Up to 125mA (MAX1836) or
250mA (MAX1837)
o Internal P-Channel MOSFET
o Efficiency Over 90%
o 12µA Quiescent Current
o 3µA Shutdown Current
o 100% Maximum Duty Cycle for Low Dropout
o Current-Limiting and Overtemperature Protection
o Small 6-Pin SOT23 Package
Ordering Information
PART
TEMP RANGE
PIN-
PA C K A G E
TOP
MARK
MAX1836EUT50-T
MAX1836EUT33-T
MAX1837EUT50-T
MAX1837EUT33-T
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
6 SOT23-6
6 SOT23-6
6 SOT23-6
6 SOT23-6
AANW
AANY
AANX
AANZ
Note: The MAX1836/MAX1837 require special solder tempera-
ture profile described in the Absolute Maximum Ratings.
PART
MAX1836EUT50
MAX1836EUT33
MAX1837EUT50
MAX1837EUT33
TOP VIEW
Selector Guide
PRESET OUTPUT
VOLTAGE (V)
5
3.3
5
3.3
LOAD
CURRENT (mA)
125
125
250
250
Pin Configuration
FB 1
6 OUT
MAX1836
GND 2 _MAX1837 5 SHDN
IN 3
4 LX
NOTE: HIGH-CURRENT PATHS SHOWN WITH BOLD LINES.
SOT23
________________________________________________________________ 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.