ML4869CS-3 MICRO-LINEAR [Micro Linear Corporation], ML4869CS-3 Datasheet

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ML4869CS-3

Manufacturer Part Number
ML4869CS-3
Description
Medium Current Boost Regulator with Load Disconnect
Manufacturer
MICRO-LINEAR [Micro Linear Corporation]
Datasheet
GENERAL DESCRIPTION
The ML4869 is a continuous conduction boost regulator
designed for DC to DC conversion in multiple cell battery
power systems. Continuous conduction allows the
regulator to maximize output current for a given inductor.
The maximum switching frequency can exceed 200kHz,
allowing the use of small, low cost inductors. The ML4869
is capable of start-up with input voltages as low as 1.8V,
and is available in 5V and 3.3V output versions with an
output voltage accuracy of ±3%.
An integrated synchronous rectifier eliminates the need
for an external Schottky diode and provides a lower
forward voltage drop, resulting in higher conversion
efficiency. In addition, low quiescent current and variable
frequency operation result in high efficiency even at light
loads. The ML4869 requires only a few external
components to build a very small regulator capable of
achieving conversion efficiencies approaching 85%.
The SHDN input allows the user to stop the regulator from
switching, and provides complete isolation of the load
from the battery.
BLOCK DIAGRAM
2
V IN
+
SHDN
V L1
START-UP
1
CONTROL
BOOST
Medium Current Boost Regulator
PWR GND
6
V L2
8
FEATURES
Guaranteed full load start-up and operation at
1.8V input
Continuous conduction mode for high output current
Pulse Frequency Modulation and internal synchronous
rectification for high efficiency
Isolates the load from the input during shutdown
Minimum external components
Low ON resistance internal switching FETs
Low supply current
5V and 3.3V output versions
Shutdown current = 1µA MAX
SYNCHRONOUS
CONTROL
RECTIFIER
with Load Disconnect
+
2.4V
GND
+
3
SHUTDOWN
CONTROL
ML4869
PRELIMINARY
SHDN
V OUT
July 2000
4
5
1

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ML4869CS-3 Summary of contents

Page 1

GENERAL DESCRIPTION The ML4869 is a continuous conduction boost regulator designed for conversion in multiple cell battery power systems. Continuous conduction allows the regulator to maximize output current for a given inductor. The maximum switching frequency can ...

Page 2

ML4869 PIN CONFIGURATION PIN DESCRIPTION PIN NAME FUNCTION 1 V Boost inductor connection Battery input voltage IN 3 GND Ground 4 SHDN Pulling this pin to V regulator, isolating the load from the input 2 ML4869 8-Pin ...

Page 3

... IL V Input High Voltage IH Input Bias Current Note 1: Limits are guaranteed by 100% testing, sampling, or correlation with worst case test conditions. OPERATING CONDITIONS Temperature Range ML4869CS-X .............................................. 0°C to 70°C ML4869ES-X ........................................... -20°C to 70°C V Operating Range ....................... 1. 0.3V OUT = Operating Temperature Range (Note 1) ...

Page 4

ML4869 SENSE 2 START-UP + – CONTROL SHDN A1 I L(MAX 27µH (SUMIDA CD75) ML4869 V L1 PWR GND GND V L2 100µF SHDN ...

Page 5

FUNCTIONAL DESCRIPTION The ML4869 combines a unique form of current mode control with a synchronous rectifier to create a boost converter that can deliver high currents while maintaining high efficiency. Current mode control allows the use of a very small ...

Page 6

ML4869 DESIGN CONSIDERATIONS OUTPUT CAPACITOR The output capacitor filters the pulses of current from the switching regulator. Since the switching frequency will vary with inductance, the minimum output capacitance required to reduce the output ripple to an acceptable level will ...

Page 7

DEISGN CONSIDERATIONS In applications where the ML4869 is operated at or near the maximum output current recommended to add a 10nF to 100nF ceramic or film capacitor from V GND. The optimum value of the high frequency bypass ...

Page 8

... PLACES) 0.055 - 0.061 (1.40 - 1.55) ORDERING INFORMATION PART NUMBER ML4869CS-3 ML4869CS-5 ML4869ES-3 ML4869ES-5 © Micro Linear 1998 registered trademark of Micro Linear Corporation. All other trademarks are the property of their respective owners. Products described herein may be covered by one or more of the following U.S. patents: 4,897,611; 4,964,026; 5,027,116; 5,281,862; 5,283,483; 5,418,502; ...

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