LR8421 datasheet(2/7 Pages) LRC

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ORDER INFORMATION

Operating free air temperature range

Output Voltage

Package

Device No.

-40~+85°C

Adjustable

SOP8-PP

LR8421AES

PIN CONFIGURATION:

Top View

SOP8-PP

Note: Recommend connecting the Thermal Pad to

the Ground for excellent power dissipation.

TYPE

(1)

DESCRIPTION

NO.

NAME

1,2

Boost and Rectifying Switch Input. Connect an inductor between this

pin and VIN. Keep the PCB trace lengths as short and wide as is practical

to reduce EMI and voltage overshoot. If the inductor current falls to zero,

or pin CE is low, an internal anti-ringing switch is connected from this pin

to VIN to minimize EMI.

VBAT

Battery Supply Input Voltage. The device gets its start-up bias from

VBAT. Once VOUT exceeds 2.3V, bias comes from VOUT. Thus, once started,

operation is completely independent from VBAT. Operation is only limited

by the output power level and the battery’s internal series resistance. The

VBAT pin should be connected to the positive terminal of the battery and

bypassed with a low ESR ceramic bypass capacitor. Care should be taken

to minimize the loop area formed by the bypass capacitor connections, the

VBAT pin, and the LR8421 PGND pin. The minimum recommended bypass

capacitance is 1 F ceramic with a X5R or X7R dielectric and the optimum

placement is closest to the VBAT pin and the PGND pin.

PCB trace length from VBAT to the input filter capacitor(s) should be as

short and wide as possible.

Chip Enable Input. Internal integrated with 1Mohm pull down resistor.

CE=High: Normal free running operation.

CE=Low: Shutdown; quiescent current <1 A. Output capacitor can be

completely discharged through the load or feedback resistors.

If CE is undefined, pin SW may ring.

LESHAN RADIO COMPANY, LTD.

Ver0.1

2/7

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