5-V Low Drop Fixed Voltage Regulator
TLE 4278 G
Features
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Output voltage tolerance
≤ ±2%
Very low current consumption
Separated reset and watchdog output
Low-drop voltage
Watchdog
Adjustable watchdog activating threshold
Adjustable reset threshold
Overtemperature protection
Reverse polarity protection
Short-circuit proof
Suitable for use in automotive electronics
Wide temperature range
AEC qualified
Green Product (RoHS compliant) version of TLE 4278 G
PG-DSO-14-30
P-DSO-14-3, -8, -9, -11, 14
Functional Description
The TLE 4278 is a monolithic integrated low-drop fixed output voltage regulator
supplying loads up to 200 mA. The IC is available in a PG-DSO-14-30 package. It is
designed to supply microprocessor systems under the severe conditions of automotive
applications and therefore equipped with additional protection functions against over-
load, short circuit and overtemperature. The TLE 4278 can also be used in other
applications where a stabilized voltage is required.
An input voltage
V
I
in the range of 5.5 V
≤
V
I
≤
45 V is regulated to
V
Q,nom
= 5 V with an
accuracy of
±2%.
The device operates in the wide temperature range of
T
j
= -40 to 150
°C.
Two additional features are implemented in the TLE 4278 a load dependent watchdog
function as well as a sophisticated reset function including power on reset, under voltage
reset, adjustable reset delay time and adjustable reset switching threshold.
Type
TLE 4278 G
Data Sheet
1
Package
PG-DSO-14-30 (RoHS compliant)
Rev. 1.4, 2007-02-19
TLE 4278 G
The watchdog function monitors the microcontroller, including time base failures. In case
of a missing rising edge within a certain pulse repetition time the watchdog output is set
to LOW. Programming of the max. repetition time can be done easily by an external reset
delay capacitor. To prevent a reset in case of missing pulses, the watchdog output WO
is separate from the reset output RO for the TLE 4278. The watchdog output can be
used as an interrupt signal for the microcontroller. In any case it is possible to connect
pin WO and pin RO externally.
When the controller is set to sleep mode or low power mode its current consumption
drops and no watchdog pulses are created. In order to avoid unnecessary wake-up
signals due to missing pulses at pin WI the watchdog feature can be disabled as a
function of the load current. The switch off threshold is set by an external resistor to pin
WADJ. The watchdog function can also be used as a timer, which periodically wakes up
the controller. Therefore the pin WADJ has to be connected to the output Q.
The power on reset feature is necessary for a defined start of the microprocessor when
switching on the application. The reset signal at pin RO goes high after a certain delay
timed
t
rd
when the output voltage of the regulator has surpassed the reset threshold. The
delay time is set by the external delay capacitor. An under voltage reset circuit
supervises the output voltage. In case
V
Q
falls below the reset threshold the reset output
is set to LOW after a short reset reaction time
t
rr
. The reset LOW signal is generated
down to an output voltage
V
Q
of 1 V. In addition the reset switching threshold can be
adjusted by an external voltage divider. This feature is useful with microprocessors
which guarantee a safe operation down to voltages below the internally set reset
threshold of 4.65 V typical.
Data Sheet
2
Rev. 1.4, 2007-02-19
TLE 4278 G
PG-DSO-14-30
WO
WADJ
GND
GND
GND
D
RADJ
1
2
3
4
5
6
7
14
13
12
11
10
9
8
AEP02113
RO
V
Ι
GND
GND
GND
V
Q
W
Ι
Figure 1
Table 1
Pin
1
2
Pin Configuration
(top view)
Pin Definitions and Functions
Symbol Function
WO
WADJ
Watchdog Output;
the open collector output is connected to the
5 V output via an integrated resistor of 30 kΩ.
Watchdog Adjust;
an external resistor to GND determines the
watchdog activating threshold.
Ground
Reset Delay;
connect a capacitor to ground for delay time
adjustment.
Reset Switching Threshold Adjust;
for setting the switching
threshold, connect a voltage divider from output to ground. If this
input is connected to ground, the reset is triggered at the internal
threshold.
Watchdog Input;
rising edge-triggered input for monitoring a
microcontroller.
5 V Output Voltage;
block to ground with min. 10
µF
capacitor,
ESR
≤
5
Ω.
Input Voltage;
block to ground directly on the IC with ceramic
capacitor.
Reset Output;
the open collector output is connected to the 5 V
output via an integrated resistor of 30 kΩ.
3, 4, 5,
GND
10, 11, 12
6
7
D
RADJ
8
9
13
14
WI
Q
I
RO
Data Sheet
3
Rev. 1.4, 2007-02-19
TLE 4278 G
V
Ι
13
9
V
Q
Temperature
Sensor
Protection
Circuit
Reset
Generator
Control
Amplifier
14
RO
7
1
RADJ
WO
D
+
-
Bandgap
Reference
Watchdog
6
3-5, 10-12
GND
2
WADJ
8
W
Ι
AEB02114
Figure 2
Block Diagram
Data Sheet
4
Rev. 1.4, 2007-02-19
TLE 4278 G
Table 2
Parameter
Absolute Maximum Ratings
Symbol
Limit Values
Min.
Max.
45
–
25
–
25
5
7
2
7
–
7
–
25
5
7
–
50
V
mA
V
mA
V
mA
V
mA
V
mA
V
mA
V
mA
V
mA
mA
–
Internally limited
–
Internally limited
–
–
–
–
–
Internally limited
–
Internally limited
–
–
–
Internally limited
–
Unit
Notes
T
j
= -40 to 150
°C
Input Voltage I
Voltage
Current
Output Voltage Q
Voltage
Current
Reset Output RO
Voltage
Current
Reset Delay D
Voltage
Current
Voltage
Current
Watchdog Input WI
Voltage
Current
Watchdog Output WO
Voltage
Current
Watchdog Adjust WADJ
Voltage
Current
Ground GND
Current
V
I
I
I
V
Q
I
Q
V
RO
I
RO
V
D
I
D
V
RADJ
I
RADJ
V
WI
I
WI
V
WO
I
WO
V
WADJ
I
WADJ
I
GND
-42
–
-1
–
-0.3
-5
-0.3
-2
-0.3
–
-0.3
–
-0.3
-5
-0.3
–
-100
Reset Switching Threshold Adjust RADJ
Data Sheet
5
Rev. 1.4, 2007-02-19
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