TLE 4261
Semiconductor Group
1
1998-11-01
Features
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Very low-drop voltage
q
Very low quiescent current
q
Low starting-current consumption
q
Proof against reverse polarity
q
Input voltage up to 42 V
q
Overvoltage protection up to 65 V (
400 ms)
q
Short-circuit proof
q
External setting of reset delay
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Integrated watchdog circuit
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Wide temperature range
q
Overtemperature protection
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Suitable for automotive use
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EMC proofed (100 V/m)
w
Please also refer to the new pin compatible
device TLE 4271
Functional Description
TLE 4261 is a 5-V low-drop voltage regulator in a P-TO220-7 or in a P-DSO package.
The maximum input voltage is 42 V (65 V/
400 ms). The device can produce an output
current of more than 500 mA. It is short-circuit proof and incorporates temperature
protection that disables the circuit at impermissibly high temperatures.
Type
Ordering Code
Package
w
TLE 4261
Q67000-A9003
P-TO220-7-1
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TLE 4261 S
Q67000-A9109
P-TO220-7-2
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TLE 4261 G
Q67000-A9059
P-DSO-20-6 (SMD)
5-V Low-Drop Voltage Regulator
Bipolar IC
TLE 4261
P-TO220-7-1
P-TO220-7-2
P-DSO-20-6
TLE 4261
Semiconductor Group
2
1998-11-01
Application Description
The IC regulates an input voltage
V
I
in the range
V
I
= 6 V to 40 V to
V
Qrated
= 5.0 V. A
reset signal is generated for a maximum output voltage of
V
Q
less than 4.75 V. The reset
delay can be set externally with a capacitor. A connected microprocessor is monitored
by the integrated watchdog circuit. Connecting this input to the input voltage makes the
watchdog function inactive. The presence of a voltage less than 2 V on inhibit input
disables the regulator. The current consumption drops to max. 50
A.
Design Notes for External Components
The input capacitor
C
I
causes a low-resistant powerline and limits the rise times of the
input voltage. The IC is protected against rise times up to 100 V/
s. It is possible to damp
the tuned circuit consisting of supply inductance and input capacitance with a resistor of
approx. 1
in series to
C
I
.
The output capacitor maintains the stability of the regulating loop. Stability is guaranteed
with a rating of 22
F at an ESR of 3
max. in the operating temperature range.
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 controls
the base of the series PNP transistor via a buffer. Saturation control as a function of the
load current prevents any over-saturation of the power element. If the output voltage
drops below 95.5 % of its typical value for more than 2
s, a reset signal is triggered on
pin 3 and an external capacitor is discharged on pin 5. The reset signal is not cancelled
until the voltage on the capacitor has exceeded the upper switching threshold
V
DT
. A
positive-edge-triggered watchdog circuit monitors the connected microprocessor and
will likewise trigger a reset if pulses are missing. The IC can be disabled by a low level
on the inhibit input and the current consumption drops to < 50
A.
The IC also incorporates a number of circuits for protection against:
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Overload
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Overvoltage
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Overtemperature
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Reverse polarity
TLE 4261
Semiconductor Group
3
1998-11-01
Pin Configuration
(top view)
Pin Definitions and Functions (TLE 4261; S)
Pin
Symbol
Function
1
V
I
Input voltage; block a capacitor directly to ground on the IC. The
capacitor rating will depend on the vehicle electrical system.
Oscillation of the input voltage can be damped by a resistor of
approx. 1
in series with the input capacitor.
2
INH
Inhibit; switches off the IC when low.
3
QRES
Reset output; open-collector output controlled by the rese delay.
4
GND
Ground
5
DRES
Reset delay; wired to ground using a capacitor.
6
Watch
Watchdog; monitors the microprocessor when active.
7
V
Q
5-V output voltage; block to ground using a capacitor of
22
F.
ESR is
3
in the operating temperature range.
AEP00592
V
INH
QRES
GND
DRES
Watch
V
Q
4
3
2
1
5
6
7
AEP01181
V
INH
QRES
GND
DRES
Watch
V
Q
4
3
2
1
5
6
7
TLE 4261
TLE 4261 S
TLE 4261
Semiconductor Group
4
1998-11-01
Pin Configuration
(top view)
Pin Definitions and Functions (TLE 4261 G)
Pin Symbol
Function
18
V
I
Input voltage; block a capacitor directly to ground on the IC. The
capacitor rating will depend on the vehicle electrical system.
Oscillation of the input voltage can be damped by a resistor of
approx. 1
in series with the input capacitor.
20
INH
Inhibit; switches off the IC when low.
3
QRES
Reset output; open-collector output controlled by the reset
delay.
4 - 7
14 - 17
GND
Ground; internally connected with pins 14 to 17.
9
DRES
Reset delay; wired to ground using a capacitor.
11
Watch
Watchdog; monitors the microprocessor when active.
12
V
Q
5-V output voltage; block to ground using a capacitor of
22
F.
ESR is
3
in the operating temperature range.
1, 2, 8, 10,
13, 19
N.C.
Not connected
AEP01182
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
N.C.
GND
GND
Watch
N.C.
INH
TLE 4261 G
TLE 4261
Semiconductor Group
5
1998-11-01
Block Diagram
Numbers in parentheses for TLE 4261 G
Overvoltage
Monitoring
Saturation
Control and
Protection
RESET
Generator
Watchdog
Temperature
Sensor
Adjustment
BANDGAP
Reference
Inhibit
-
+
7
(12)
5
(9)
3
(3)
(11) 6
4
(14-17)
(4-7)
2
(20)
1
(18)
Input
Inhibit
GND
Watchdog
Output
RESET
Delay
RESET
Output
AEB00002
Control
Amplifier
Buffer
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