Q67000-A9446(2001) データシートの表示（PDF） - Infineon Technologies

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Q67000-A9446
(Rev.:2001)

5-V Low-Drop Fixed Voltage Regulator

Infineon Technologies 

TLE 4271-2

Circuit Description

The control amplifier compares a reference voltage, which is kept highly accurate by

resistance adjustment, to a voltage that is proportional to the output voltage and drives

the base of a series transistor via a buffer. Saturation control as a function of the load

current prevents any over-saturation of the power element.

The reset output RO is in high-state if the voltage on the delay capacitor CD is greater or

equal VUD. The delay capacitor CD is charged with the current ID for output voltages

greater than the reset threshold VRT. If the output voltage gets lower than VRT (’reset

condition’) a fast discharge of the delay capacitor CD sets in and as soon as VD gets lower

than VLD the reset output RO is set to low-level.

The time for the delay capacitor charge from VUD to VLD is the reset delay time tD.

When the voltage on the delay capacitor has reached VUD and reset was set to high, the

watchdog circuit is enabled and discharges CD with the constant current IDWD. If there is

no rising edge observed at the watchdog input, CD will be discharge down to VLDW, then

reset output RO will be set to low and CD will be charged again with the current IDWC until

VD reaches VUD and reset will be set high again.

If the watchdog pulse (rising edge at watchdog input WI) occurs during the discharge

period CD is charged again and the reset output stays high. After VD has reached VUD,

the periodical behavior starts again.

Internal protection circuits protect the IC against:

• Overload

• Overvoltage

• Overtemperature

• Reverse polarity

Data Sheet Rev. 2.4

3

2001-04-04

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