APW7085K データシートの表示（PDF） - Anpec Electronics

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APW7085K

2A, 26V, 380kHz, Asynchronous Step-Down Converter

Anpec Electronics 

APW7085

Function Description (Cont.)

Output Under-Voltage Protection (Cont.)

2µs noise filter to prevent the chips from wrong UVP shut-

down caused by noise. The under-voltage protection

works in a hiccup mode without latched shutdown. The

IC will initiate a new soft-start process at the end of the

preceeding delay.

Over-Temperature Protection (OTP)

The over-temperature circuit limits the junction tempera-

ture of the APW7085. When the junction temperature ex-

ceeds TJ=+150oC, a thermal sensor turns off the power

MOSFET, allowing the devices to cool. The thermal sen-

sor allows the converter to start a start-up process and

regulate the output voltage again after the junction tem-

perature cools by 50oC. The OTP is designed with a 50oC

hysteresis to lower the average T during continuous ther-

J

mal overload conditions, increasing lifetime of the IC.

Enable/Shutdown

Driving EN to ground places the APW7085 in shutdown.

When in shutdown, the internal power MOSFET turns off,

all internal circuitry shuts down and the quiescent supply

current of VIN reduces to <1µA (typical).

Current-Limit Protection

The APW7085 monitors the output current, flowing through

the P-channel power MOSFET, and limits the current peak

at current-limit level to prevent loads and the IC from dam-

ages during overload or short-circuit conditions.

Frequency Foldback

When the output is shortened to the ground, the frequency

of the oscillator will be reduced to about 80kHz. This lower

frequency allows the inductor current to safely discharge,

thereby preventing current runaway. The oscillator’s fre-

quency will gradually increase to its designed rate when

the feedback voltage on FB again approaches 0.8V.

Copyright © ANPEC Electronics Corp.

16

Rev. A.7 - Sep., 2010

www.anpec.com.tw

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