LD6919

4/12/2010

8

Leadtrend Technology Corporation

www.leadtrend.com.tw

LD6919-DS-00b April 2010

Application Information

Operation Overview

An input capacitor whose value at least 1

μF is necessary

to place between the VIN pin and GND to stabilize VIN

and obtain beneficial effect. Besides, the input capacitor

should be located in the distance within 5mm from the VIN

pin.

The output capacitor also should be located in the

distance within 5mm from the OUT pin. The LD6919 is

designed specifically operating with low ESR ceramic

output capacitor in space-saving and performance

consideration. Using a ceramic capacitor whose value is

at least 1μF with ESR is > 25mΩ on the LD6919 output

ensures stability. X5R or X7R types of capacitors are

recommended for the input and output capacitors in full

range of operation temperature.

Soft Start Operation and Noise Reduction

between SS pin and GND can provide soft start operation

and reduce output noise dramatically. The soft start time

can be estimated by following formula.

(ms)

C

35

.

0

T

SS

Where,

EX:

The soft start time, TSS ≈ 0.35*22=7.7 (ms)

If the soft start function is not necessary, open this pin will

achieve VOUT to quick start up.

Output Voltage

The output voltage can be set by the value chosen for the

following formula.

)

R

(w/o

V

73

)

k

(

R

)

k

(

R

)

(w.R

V

J

OUT

J

J

J

OUT

×

+

Ω

Ω

=

recommended.

Enable Function

The LD6919 features an enable/disable function. To apply

to CE pin with a logic high level above 1.5V to assure the

device will be complete turn-on. The LD6919 will enter

shutdown mode when the CE voltage falls below 0.6V.

During shutdown mode, the shutdown current for the

device is less than 1μA (max).

Current Limit

Output current is limited to 600mA (typical). When current