1

LTC1626

Low Voltage, High Efficiency

Step-Down DC/DC Converter

FEATURES

The LTC

current mode DC/DC converter featuring Burst Mode

TM

operation at low output current.

The input supply voltage range of 2.5V to 6V makes the

LTC1626 ideal for single cell Li-Ion and 3- or 4-cell NiCd/

NiMH applications. A built-in 0.32

allows up to 0.6A of output current.

The LTC1626 incorporates automatic power saving Burst

Mode operation to reduce gate charge losses when the

load current drops below the level required for continuous

operation. With no load, the converter draws only 165

µA.

In shutdown, it draws a mere 0.5

µA—making it ideal for

current sensitive applications.

The inductor current is user-programmable via an external

current sense resistor. In dropout, the internal P-channel

MOSFET switch is turned on continuously, maximizing

battery life.

, LTC and LT are registered trademarks of Linear Technology Corporation.

Burst Mode is a trademark of Linear Technology Corporation.

Figure 1. High Efficiency 2.5V Step-Down Converter

OUTPUT CURRENT (A)

0.01

100

95

90

85

80

75

70

0.1

1

1626 F01a

L1 = 33

µH

Efficiency

+

SGND

D1

MBRS130LT

0.1

µF

* COILTRONICS CTX33-4

** IRC 1206-R100F

270pF

470

Ω

1000pF

3900pF

10k

1626 F01

10k

100pF

L*

33

µH

0.1

Ω

2.5V

0.25A

††

100

µF

6.3V

2.7V TO 6V

†

47

µF

16V

SW

LTC1626

SHDN

PGND

+

s

Single Cell Li-Ion Step-Down Converters

s

3- or 4-Cell NiMH Step-Down Converters

s

Cellular Telephones

s

5V to 3.3V Conversion

s

3.3V to 2.5V Conversion

s

Inverting Converters

s

Portable Instruments

s

Wide Input Supply Voltage Range: 2.5V to 6V

s

High Efficiency: Up to 95%

s

s

Current Mode Operation for Excellent Line and Load

Transient Response

s

Short-Circuit Protected

s

Low Dropout Operation: 100% Duty Cycle

s

Built-In Low-Battery Detector

s

s

s

Peak Inductor Current Independent of Inductor Value

s

Available in 14-Pin SO Package