5-V Low-Drop Fixed Voltage Regulator
TLE 4268
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
P-DSO-8-1
Type
TLE 4268 GS
TLE 4268 G
Ordering Code
Q67006-A9229
Q67006-A9146
Package
P-DSO-8-1 (SMD)
P-DSO-20-6 (SMD)
P-DSO-20-6
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.
Semiconductor Group
1
1998-11-01
TLE 4268
Pin Configuration
(top view)
P-DSO-8-1
V
Ι
N.C.
QRES
GND
1
2
3
4
8
7
6
5
AEP01954
V
Q
W
SRES
DRES
Figure 1
Pin Definitions and Functions
Pin
1
2
3
4
5
6
7
8
Symbol
Function
Input voltage
Not connected
Reset output
Ground
Reset delay
Reset switching threshold
Watchdog input
5-V output voltage
V
I
N. C.
QRES
GND
DRES
SRES
W
V
Q
Semiconductor Group
2
1998-11-01
TLE 4268
Pin Configuration
(top view)
P-DSO-20-6
N.C.
N.C.
QRES
GND
GND
GND
GND
N.C.
DRES
SRES
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
AEP01540
N.C.
N.C.
V
Ι
GND
GND
GND
GND
N.C.
V
Q
W
Figure 2
Pin Definitions and Functions
Pin
Symbol Function
Not connected.
Reset output;
the open collector output is connected to the
5-V output via an integrated resistor of 30 kΩ.
Ground
Reset delay;
connect a capacitor to ground for delay time
adjustment.
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.
Watchdog input;
positive-edge-triggered input for monitoring a
microcontroller.
5-V output voltage;
block to ground with 22-µF capacitor,
ESR
<
3
Ω.
Input voltage;
block to ground directly on the IC with ceramic
capacitor.
3
1998-11-01
1, 2, 8, 13, N. C.
19, 20
3
4 … 7,
14 … 17
9
10
QRES
GND
DRES
SRES
11
12
18
W
V
Q
V
I
Semiconductor Group
TLE 4268
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
Input
18
12 Output
Temperature
Sensor
Protection
Circuit
Reset
Generator
Control
Amplifier
+
-
3 Reset
Output
Reset
10 Switching
Threshold
9 Reset
Delay
Adjustment
Bandgap
Reference
Watchdog
4-7, 14-17
GND
11
Watchdog
Input
AEB01539
Figure 3
Block Diagram
Semiconductor Group
4
1998-11-01
TLE 4268
Absolute Maximum Ratings
T
j
= – 40 to 150
°C
Parameter
Symbol
Limit Values
min.
Input
Input voltage
Input current
Reset Output
Voltage
Current
Reset Delay
Voltage
Current
Watchdog
Watchdog input
Reset Input
Reset threshold
Output
Output voltage
Output current
Ground
Current
Temperatures
Junction temperature
Storage temperature
max.
Unit
Notes
V
I
I
I
– 30
45
V
Internally limited
V
R
I
R
– 0.3
7
V
Internally limited
V
D
I
D
– 0.3
7
V
Internally limited
V
W
– 0.3
7
V
–
V
RE
– 0.3
7
V
–
V
Q
I
Q
– 0.3
7
V
Internally limited
I
M
– 100
50
mA
–
T
j
T
S
– 50
150
150
°C
°C
–
Semiconductor Group
5
1998-11-01
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