LT3593 datasheet(9/16 Pages) LINER

9 / 16 page

LT3593

3593f

APPLICATIONS INFORMATION

Figure 5. Output Open-Circuit Waveform

Figure 6. Two AA Cells to Three White LEDs

Overvoltage Protection

The LT3593 has an internal open-circuit protection circuit.

In the case of an output open circuit, when the LEDs are

disconnected from the circuit or the LEDs fail open, VCAP

is clamped at 38V. The LT3593 will then switch at a very

low frequency to minimize input current. VCAP and input

current during output open circuit are shown in the Typical

Performance Characteristics. Figure 5 shows the transient

response when the LEDs are disconnected.

Low Input Voltage Applications

The LT3593 can be used in low input voltage applications.

The input supply voltage to the LT3593 must be 2.7V or

higher, but the inductor can be run off a lower battery

voltage. This technique allows the LEDs to be powered off

two alkaline cells. Most portable devices have a 3.3V logic

supply voltage which can be used to power the LT3593.

The LEDs can be driven straight from the battery, resulting

in higher efﬁciency.

Figure 6 shows three LEDs powered by two AA cells.

The battery is connected to the inductors and the chip is

powered off a 3.3V logic supply voltage.

CTRL

C1: TAIYO YUDEN EMK107B5105MA

C2: MURATA GRM31MR71H105KA88

L1: MURATA LQH43CN100

D1: CENTRAL CMDSH05-4

VIN

10μH

2 AA CELLS

2V TO 3.2V

3.3V

3593 F06

LT3593

SHUTDOWN AND

CURRENT CONTROL

CAP

LED

GND

1μF

VCAP

20V/DIV

400μs/DIV

VIN = 3.6V

FRONT PAGE

APPLICATION CIRCUIT

3593 F05

200mA/DIV

VSW

20V/DIV

LEDs DISCONNECTED

AT THIS INSTANT

LT3593 Datasheet(PDF) 9 Page - Linear Technology

LT3593 Datasheet(HTML) 9 Page - Linear Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Datasheet Download

Link URL