AP3602BKTR データシートの表示（PDF） - BCD Semiconductor

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AP3602BKTR

100mA REGULATED CHARGE PUMP

BCD Semiconductor 

Data Sheet

100mA REGULATED CHARGE PUMP

AP3602A/B

Application Information

Operating Principles

The AP3602A/B use a switched capacitor charge

pump to boost the input voltage to a regulated output

voltage. Regulation is achieved by sensing the chip

output voltage through an internal resistor divider net-

work. Controlled by an internal comparator (refer to

the functional block diagram), the charge pump circuit

is enabled when the divided output voltage is below a

preset trip point .

The charge pump operates at 1.2MHz with 50% duty

cycle. Conversion consists of a two-phase operation. In

the first phase, switches S2 and S3 are opened and S1

and S4 are closed. During this time, CFLY charges to

the voltage on VIN and load current is supplied by

COUT. During the second phase, S2 and S3 are closed,

and S1 and S4 are opened. This action connects CFLY

low side to VIN, CFLY high side to VOUT, then a volt-

age about 2*VIN is used to charge COUT and supply the

load current. For each cycle, charges is transported

from VIN to VOUT to maintain the output voltage in its

nominal value.

This process breaks when the VOUT is high enough for

the reason of higher input voltage or lower load, then

the divided voltage at the control comparator exceeds

the internal trip point high level, which compels the

charge pump circuit enter to the idle mode in which the

switching cycle stops (pulse skipping) and the output

voltage is continually decreased because it is main-

tained by the discharging of COUT only. In idle mode,

the feedback circuit continues sensing VOUT. If the

divided voltage at the control comparator drops below

the preset trip point, the comparator will start the

switching cycle again.

In idle mode, the AP3602A/B's quiescent current is

about 13µA. In shutdown mode, all internal circuitry is

turned off and the AP3602A/B draw only leakage cur-

rent from VIN, which is less than 1µA. So, the shut-

down power loss for AP3602A/B is very low, that is

beneficial to the battery supplied systems.

Short Circuit and Thermal Protection

The AP3602A/B have a thermal protection and shut-

down circuit that continuously monitors the IC junc-

tion temperature.

When output short circuit occurs, the short circuit cur-

rent is about 300mA (Typical). Under this condition,

the IIN is about 2*Iout, which causes about 1.8W

instant power dissipation on AP3602A/B, that will

cause a rise in the internal IC junction temperature. If

the thermal protection circuit senses the junction tem-

perature exceeding approximately 160oC, the thermal

shutdown circuit will disable the charge pump switch-

ing circuit. The thermal hysteresis is about 10oC, which

means that the charge pump circuit can be active when

the short circuit is removed and the junction tempera-

ture drops below 150oC.

The thermal shutdown protection will cycle on and off

if an output short circuit condition persists. This will

allow the AP3602A/B to operate on a short circuit con-

dition without latch up or damage to the device.

Apr. 2007 Rev. 1.2

BCD Semiconductor Manufacturing Limited

7

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