P-DSO-8-1
P-DSO-20-6
5-V Low-Drop Fixed Voltage Regulator
TLE 4268
Semiconductor Group
1
1998-11-01
Features
Output voltage tolerance
2 %
Very low current consumption
Low-drop voltage
Watchdog
Settable reset threshold
Overtemperature protection
Reverse polarity protection
Short-circuit proof
Suitable for use in automotive electronics
Wide temperature range
Type
Ordering Code
Package
TLE 4268 GS
Q67006-A9229
P-DSO-8-1 (SMD)
TLE 4268 G
Q67006-A9146
P-DSO-20-6 (SMD)
Functional Description
This device is a 5-V low-drop fixed-voltage regulator. The maximum input voltage is
45 V. It can deliver an output current of at least 180 mA. The IC is short-circuit proof and
features temperature protection that disables the circuit in the event of impermissibly
high temperatures. The watchdog function is disabled as a function of the load, so that
a controller is not interrupted during sleep mode by a watchdog reset.
Application Description
The IC regulates an input voltage
V
i
in the range 5.5 V
<
V
i
<
45 V to
V
qrated
= 5.0 V. In
the event of an output voltage
V
Q
<
V
RT
, a reset signal is generated. The wiring of the
reset switching threshold input enables the value of
V
RT
to be reduced. The reset delay
time can be adjusted using an external capacitor. The integrated watchdog monitors the
connected active controller. If there is no positive-going edge at the watchdog input, the
reset output is set to low. The reset delay capacitor provides a wide adjustment range
for the pulse repetition time. The watchdog function is only activated if the load exceeds
8 mA. This ensures that a microcontroller is not activated during power-down and the
current drain is not increased. The IC is protected against overload and
overtemperature.
TLE 4268
Semiconductor Group
2
1998-11-01
Pin Configuration
(top view)
Figure 1
Pin Definitions and Functions
Pin
Symbol
Function
1
V
I
Input voltage
2
N. C.
Not connected
3
QRES
Reset output
4
GND
Ground
5
DRES
Reset delay
6
SRES
Reset switching threshold
7
W
Watchdog input
8
V
Q
5-V output voltage
P-DSO-8-1
SRES
W
GND
5
6
7
N.C.
8
4
3
2
1
V
Q
AEP01954
V
QRES
DRES
TLE 4268
Semiconductor Group
3
1998-11-01
Pin Configuration
(top view)
Figure 2
Pin Definitions and Functions
Pin
Symbol Function
1, 2, 8, 13,
19, 20
N. C.
Not connected.
3
QRES
Reset output; the open collector output is connected to the
5-V output via an integrated resistor of 30 k
.
4 ... 7,
14 ... 17
GND
Ground
9
DRES
Reset delay; connect a capacitor to ground for delay time
adjustment.
10
SRES
Reset switching threshold; for setting the switching threshold,
output to ground with voltage divider. If this input is connected to
ground, the reset is triggered at an output voltage of 4.5 V.
11
W
Watchdog input; positive-edge-triggered input for monitoring a
microcontroller.
12
V
Q
5-V output voltage; block to ground with 22-
F capacitor,
ESR
<
3
.
18
V
I
Input voltage; block to ground directly on the IC with ceramic
capacitor.
AEP01540
GND
Q
V
V
N.C.
N.C.
13
14
10
15
9
16
8
17
N.C.
7
18
6
19
GND
5
20
4
3
2
1
GND
GND
N.C.
DRES
11
12
QRES
GND
GND
SRES
GND
GND
W
N.C.
N.C.
P-DSO-20-6
TLE 4268
Semiconductor Group
4
1998-11-01
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
V
ST
, a reset signal is generated on the reset output and not cancelled
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
AEB01539
Temperature
Sensor
-
+
Control
Amplifier
Protection
Circuit
Reference
Bandgap
Adjustment
Generator
Reset
Watchdog
Watchdog
Input
3
12
10
9
Output
Reset
Reset
Reset
Output
Switching
Delay
11
Threshold
18
Input
4-7, 14-17
GND
TLE 4268
Semiconductor Group
5
1998-11-01
Absolute Maximum Ratings
T
j
= 40 to 150
C
Parameter
Symbol
Limit Values
Unit
Notes
min.
max.
Input
Input voltage
Input current
V
I
I
I
30
45
V
Internally limited
Reset Output
Voltage
Current
V
R
I
R
0.3
7
V
Internally limited
Reset Delay
Voltage
Current
V
D
I
D
0.3
7
V
Internally limited
Watchdog
Watchdog input
V
W
0.3
7
V
Reset Input
Reset threshold
V
RE
0.3
7
V
Output
Output voltage
Output current
V
Q
I
Q
0.3
7
V
Internally limited
Ground
Current
I
M
100
50
mA
Temperatures
Junction temperature
Storage temperature
T
j
T
S
50
150
150
C
C
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