TLE4268 Siemens Semiconductor Group, TLE4268 Datasheet - Page 4

• Manufacturer Part Number: TLE4268
• Description: 5-V Low-Drop Fixed Voltage Regulator
• Manufacturer: Siemens Semiconductor Group

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 the series transistor via a buffer. Saturation control as a function of the load
current prevents any over-saturation of the power element. If The externally scaled down
output voltage at the reset threshold input drops below 1.35 V, the external reset delay
capacitor is discharged by the reset generator. If the voltage on the capacitor reaches
the lower threshold
again until the upper threshold voltage is exceeded. If the reset threshold input is
connected to GND, reset is triggered at an output voltage of 4.5 V. A connected
microcontroller is monitored by the watchdog logic. If pulses are missing, the rest output
is set to low. The pulse sequence time can be set within a wide range with the reset delay
capacitor. The IC also incorporates a member of internal circuits for protection against:
• Overload
• Overtemperature
• Reverse polarity
Figure 3
Block Diagram
Semiconductor Group
Input
18
Adjustment
V
ST
, a reset signal is generated on the reset output and not cancelled
Temperature
Reference
Bandgap
Sensor
GND
4-7, 14-17
4
Amplifier
Control
Protection
Circuit
Generator
Watchdog
Watchdog
Reset
Input
11
12
10
3
9
TLE 4268
Output
Reset
Output
Reset
Switching
Threshold
Reset
Delay
1998-11-01
AEB01539