RT9513

8

DS9513-01 April 2011

www.richtek.com

Figure 2

Temperature Regulation and Thermal Protection

In order to maximize the charge rate, the RT9513 features a junction temperature regulation loop. If the power dissipation

of the IC results in a junction temperature greater than the thermal regulation threshold (125

°C), the RT9513 throttles

back on the charge current in order to maintain a junction temperature around the thermal regulation threshold (125

°C).

125

°C. This operation continues until junction temperature falls below thermal regulation threshold (125°C) by the

hysteresis level. This feature prevents the chip from damage.

Selecting the Input and Output Capacitors

In most applications, the most important is the high-frequency decoupling capacitor on the input of the RT9513. A 1uF

ceramic capacitor, placed in close proximity to input pin and GND pin is recommended. In some applications depending

on the power supply characteristics and cable length, it may be necessary to add an additional 10uF ceramic capacitor

to the input. The RT9513 requires a small output capacitor for loop stability. A 1uF ceramic capacitor placed between the

BATT pin and GND is typically sufficient.

Layout Consideration

The RT9513 is a fully integrated low cost single-cell Li- Ion battery charger ideal for portable applications. Careful PCB

layout is necessary. For best performance, place all peripheral components as close to the IC as possible. A short

connection is highly recommended. The following guidelines should be strictly followed when designing a PCB layout

for the RT9513.

Input capacitor should be placed close to IC and connected to ground plane. The trace of input in the PCB should be

placed far away the sensitive devices or shielded by the ground.

The GND should be connected to a strong ground plane for heat sinking and noise protection.

noise coupling.

Output capacitor should be placed close to IC and connected to ground plane to reduce noise coupling.

9

8

7

1

2

3

4

5

10

GND

C3

C1

ACIN

NC

GND

CHG_S

PGOOD

BATT

NC

ISETA

NC

EN

GND

The capacitor should be

placed close to IC pin and

connected to ground plane.

The GND should be

connected to a strong

ground plane for heat

sinking and noise

protection.

should be isolated from other

noisy traces. The short wire

is recommended to prevent

EMI and noise coupling.