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Preliminary
TECHNICAL DATA
5-V Low-Drop Fixed Voltage Regulator
ILE 4278
Features
Functional Description The ILE 4278 is a monolithic integrated low-drop fixed-voltage regulator which can supply loads up to 200 mA. The device is available in the 14-SOP-225 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. Of course the ILE 4278 can also be used in other applications where a stabilized voltage is required.
An input voltage V I in the range of 28V VI 45 V is regulated to VQ,nom = 5 V with an accuracy of 4%. The device operates in the wide temperature range of Tj = - 40 to 12 5 C. Two additional features are implemented in the ILE 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. 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
(R)
(R)
(R)
(R)
An input voltage VI in the range of accuracy of 2%.
(R)
* * * * * * * * * * * *
2%, 4% Output voltage tolerance 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
P-DSO-14-8
6V
VI 28V is regulated to VQ,nom = 5 V with an
Rev. 00
1
ILE 4278
delay capacitor. To prevent a reset in case of missing pulses, the watchdog output WO is separate from the reset output RO for the ILE 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 trd 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 VQ falls below the reset threshold the reset output is set to LOW after a short reset reaction time trr. The reset LOW signal is generated down to an output voltage VQ 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.
Rev. 00
2
ILE 4278
Pin Configuration (top view) 14-SOP
WO WADJ GND GND GND D RADJ 1 2 3 4 5 6 7 14 13 12 11 10 9 8 RO V GND GND GND VQ W
Figure 1 Pin Definitions and Functions Pin 1 2 Symbol Function WO WADJ Watchdog Output; the open collector output is connected to the 5 V output via an integrated resistor of 30 k. 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 F capacitor, ESR 5 . 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 k.
GND 3, 4, 5, 10, 11, 12 6 7 D RADJ
8 9 13 14
WI
I
RO
Q
(R)
Rev. 00
3
ILE 4278
Block Diagram
V
13
9
VQ
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
Figure 2
Rev. 00
4
ILE 4278
Absolute Maximum Ratings
Tj = - 40 to 150 C
Parameter
Input Voltage I Voltage Current Output Voltage Q Voltage Current Reset Output RO Voltage Current Reset Delay D Voltage Current
Reset Switching Threshold Adjust RADJ Voltage Current Watchdog Input WI Voltage Current Watchdog Output WO Voltage Current
Symbol
Limit Values min. max.
Unit
Notes
VI II
- 42 -
45 V -
- mA Internally limited
VQ IQ
-1 -
25 -
V mA
- Internally limited
VRO IRO
- 0.3 -5
25 5
V mA
- -
VD ID
- 0.3 -2
7 2
V mA
- -
VRADJ IRADJ
- 0.3 -
7 -
V mA
- Internally limited
VWI IWI
- 0.3 -
7 -
V mA
- Internally limited
VWO IWO
- 0.3 -5
25 5
V mA
- -
Rev. 00
5
ILE 4278
Absolute Maximum Ratings (cont'd)
Tj = - 40 to 150 C
Parameter
Watchdog Adjust WADJ Voltage Current Ground GND Current Temperatures
Storage temperature
Tstg
- 50
150
Note: ESD protection according to MIL Std. 883: 2 kV. Maximum ratings are absolute ratings; exceeding any one of these values may cause irreversible damage to the integrated circuit. Operating Range Parameter Input voltage Junction temperature Thermal Resistance Junction ambient Junction pin
1)
Symbol
Limit Values min. max. 45 125 6.0 - 40
Unit V C
Rthj-a Rthj-pin
80
- -
80 30
Package mounted on PCB 80
1.5 mm3; 35Cu ; 5Sn; Heat Sink Area 6 cm2; zero airflow.
Note: In the operating range the functions given in the circuit description are fulfilled.
VI Tj
K/W K/W

Junction temperature
Symbol
Limit Values min. max.
Unit
Notes
VWADJ IWADJ
- 0.3 -
7 -
V mA
- Internally limited
IGND
- 100
50
mA
-
Tj
- 40
150
C C
- -
Notes - -
1)
Measured to pin 4
Rev. 00
6
ILE 4278
Electrical Characteristics Parameter Output voltage Output voltage Output current limiting Current consumption Iq = I I - I Q Current consumption Iq = I I - I Q Current consumption Iq = I I - I Q Drop voltage; VDR = VI - VQ Load regulation Line regulation Symbol
Iq,150 Vdr VQ.lo VQ,li
- -
5 0.25
12 0.5 - 20
mA V mV mV
IQ = 150 mA1) IQ = 5 to 150 mA; VI = 6 V VI = 6 to 28 V IQ = 5 mA
- 30 - 5 - 5
Reset Generator Reset threshold Reset headroom
VQ,rt VQ,rt =
4.5 180
4.65 350
4.8 -
V mV
RADJ connected to GND
IQ = 10 mA
(VQ,nom - VQ,rt) Reset low voltage Reset high voltage Reset pull-up Charging current - 4.5 20 2 0.20 - 30 5 0.40 - 46 8 V V k A
VRO,h RRO ID,c
-
Internal connected to VQ
VD = 1.0 V
=
Reset adjust threshold
VRADJ,th VRO,l
1.28 1.35
1.45
V
VQ 3.5 V Rext = 10 k=to VQ VQ 1 V
=
Iq,o
-
210
230
A
IQ = 0 mA; Tj = 85 C IQ = 150 mA
IQ Iq,o
200 -
400 180
- 200
mA A
VQ = 4.8 V Tj = 25 C; IQ = 0 mA
(R) (R)
(R) (R)
VQ
4.8
5.0
5.2
V
1 mA IQ 50 mA; 28 V VI 45 V
(R)
(R)
(R)
VQ
(R)

(R)
VI = 13.5 V; - 40 C Tj
125 C (unless otherwise specified) Limit Values min. typ. 4.90 5.00 max. 5.10 V 1mA IQ 150 mA; 6 V VI 28 V Unit Test Condition
(R)
Rev. 00
7
ILE 4278
Electrical Characteristics (cont'd) Parameter Symbol
Upper timing threshold Lower reset timing threshold Delay time Reset reaction time Watchdog Activating threshold Current ratio Slew rate Watchdog low voltage Watchdog high voltage Watchdog pull-up Charge current
VDU VDRL trd trr
dVWI/dt
5 - 4.5 20 2 0.6 1.5 0.5 42 7 35
- 0.2 - 30 5 1.3 1.9 0.7 60 13 47
- 0.4 - 46 8 2.0 2.3 0.9 80 19 61
V/s From 20% up to 80% VQ V V k A A
VWOL VWOH RWO
Rext > 10 k to VQ
- Internally connected to
V V ms ms ms
threshold Watchdog output pulse period Watchdog output low time Watchdog trigger time
1)
TWD,p tWD,l TWI,tr
Measured when the output voltage VQ has dropped 100 mV from the nominal value.

ID,wc Discharge current ID,wd Upper timing threshold VDU Lower watchdog timing VDWL
VQ VD = 1.0 V VD = 1.0 V
- -
Cd = 47 nF VQ > VRT Cd = 47 nF
(R)
VWADJ,th IQ/IWADJ
1.28 1.35 650 720
1.45 800
V -
(R)
VI = 13.5 V; - 40 C Tj
125 C (unless otherwise specified) Limit Values min. typ. 1.5 0.2 12 0.4 1.9 0.3 20 1.0 max. 2.3 0.4 28 2.0 V V ms s - - Unit Test Condition
(R)
CD = 47 nF CD = 47 nF
Voltage at WADJ
IQ
10 mA
Rev. 00
8
ILE 4278
Test Circiut
C 1 1000 F WO V VWO VWADJ C 2 470 nF
WO
V
13
9
VQ
Q
CQ 10 F
WADJ WADJ
W
1 2 8 6 D
ILE 4278
3-5, 10-12 GND CD 47 nF RO 14 7 RADJ
RO
VRO
VQ
VW VD
GND
VRE
VDR = V -VO Outside the control range
Figure 3
Rev. 00
9
ILE 4278
Application Information Input, Output The input capacitors CI1 and CI2 are necessary for compensating line influences. Using a resistor of approx. 1 in series with CI1, the LC circuit of input inductance and input capacitance can be damped. To stabilize the regulation circuit the output capacitor CQ is necessary. Stability is guaranteed at values CQ 10 F with an ESR 5 within the operating temperature range. Application Circuit
V
C 1 C2 13 9
+12 V
VQ
R1 CQ 22 F
470 nF
1
WO
RO W RADJ
ILE 4278
3-5, 10-12 GND Cooling Area CD
14 8
6 D
7 2 WADJ
*)
47 nF
R WADJ
R2
*) or short to GND
for internal threshold
Figure 4
(R)
P
Rev. 00
10
ILE 4278
Reset Timing The power-on reset delay time is defined by the charging time of an external capacitor CD which can be calculated as follows:
Definitions:
CD = delay capacitor trd = delay time ID,c = charge current, typical 5 A V = VDU, typical 1.9 V VDU = upper delay switching threshold at CD for reset delay time The reset reaction time trr is the time it takes the voltage regulator to set the reset out
LOW after the output voltage has dropped below the reset threshold. It is typically 1 s for delay capacitor of 47 nF. For other values for CD the reaction time can be estimated using the following equation:
Reset Timing (Watchdog Disabled)
V
VQ
VD
t rd VRO
t rr
Power-on-Reset
Thermal Shutdown
trr
20 s/F
CD
< t rr V Q, rt d V D,c = dt CD
t
t V DU V DRL t
t Voltage Dip at Input Undervoltage Secondary Spike Overload at Output
Figure 5
Rev. 00
CD = (trd
ID,c)/V

11
ILE 4278
Reset Switching Threshold The present default value is 4.65 V. When using the ILE 4278 the reset threshold can be set to 3.5 V < VQ,rt < 4.6 V by connecting an external voltage divider to pin RADJ. The calculation can be easily done since the reset adjust input current can be neglected. If this feature is not needed, the pin has to be connected to GND.
VQ,rt = Vref(1 + R1/R2)
Definitions:
VQ,rt = Reset threshold Vref = comparator reference voltage, typical 1.35 V
ILE 4278 13 9 Q
Band-GapReference 1.35 V >1
Band-GapReference 1.35 V
Figure 6
The reset output pin is internally connected to the 5 V output Q via a 30 k pull-up resistor. Down to an output voltage VQ of typical 1 V the reset LOW signal at pin RO is generated. For the timing of the reset feature please refer to the data sheet, Figure 5.
(Reset adjust input current
50 nA)
30 k 14 RO
+ -
R1 7 3 ... 5, 10 ... 12 GND R2 RADJ
Rev. 00
12
ILE 4278
Watchdog Activating The calculation of the external resistor which adjusts the watchdog switch off threshold can be done by the following equation.
Definitions:
VWADJ,th = switch off threshold, typical 1.35 V IQ/IWADJ = current ratio, typical 720 IQ,act = switch off load current
Band-GapReference
WADJ
R WADJ GND
RWADJ = VWADJ,th
(IQ/IWADJ)/IQ,act
ILE 4278 Q
HIGH Watchdog active LOW Watchdog disabled
+ -
Figure 7
Rev. 00
13
ILE 4278
Watchdog Timing The frequency of the watchdog pulses has to be higher than the minimum pulse sequence which is set by the external reset delay capacitor CD. Calculation can be done according to the formulas given in Figure 8. The watchdog output is internally connected to the output Q via a 30 k pull-up resistor. To generate a watchdog created reset signal for the microcontroller the pin WO can be connected to the reset input of the microcontroller. It is also allowed to parallel the watchdog out to the reset out. Timing of the Watchdog Function
VW
V
t
VQ
T WD, p
t
VD VDU VDWL VWO
T WI, tr
t
t WD, L
t
T WI, tr =
(VDU - VDWL )
D, wd
C D ; T WD, p =
(VDU -VDWL ) ( D, wc + D, wd )
D, wc x D, wd
C D ; t WD, L =
(VDU - VDWL )
t CD
D, wc
Figure 8
Rev. 00
14
ILE 4278
Hints for Unused Pins Symbol RO D RADJ WI WO WADJ Function Reset output Reset delay Reset switching threshold adjust Watchdog input Watchdog output Watchdog adjust Connect to open open or to output Q GND GND open
1)
2)
to output Q via a 270 k resistor: Watchdog always active to GND: Watchdog disabled
Rev. 00
15
ILE 4278
Drop Voltage Vdr versus Output Current IQ
mV V dr 700 600 500 400 Tj = 125 C 300 Tj = 25 C 200 100 0
Current Consumption Iq versus Output Current IQ
16 I q mA 14 12 10 8 6 4 2 0
VI = 13.5 V T j = 25 C
0
50
100
150
200
250
mA
0
50
100
150
200
mA 300
Q
IQ
Current Consumption Iq versus Input Voltage VI
12
Output Voltage VQ versus Input Voltage VI
mA
Iq mA
10
Tj = 25 C
VQ 10
8
8
6
R L= 33
6 R L= 33 4
4
R L= 50
2
R L= 100
0 10 20 30 40 V 50 VI
2
0
0
0
2
4
6
8 V
V
Rev. 00
16
ILE 4278
Charge Current ID,wc and Discharge Current ID,wd versus Temperature Tj
8 A 7 6 5 4 3 2 1 0 -40
Switching Voltage VDU, VDWL and VDRL versus Temperature Tj
3.2 V 2.8 V = 13.5 V 2.4
V = 13.5 V VD = 1.0 V
VD
D, wc
2.0 1.6 1.2 0.8 0.4 0 -40
V DU
D, wd
V DWL V DRL
0
40
80
120 Tj
C
0
40
80
120 C 160 Tj
Output Voltage VQ versus Temperature Tj
5.2 VQ V 5.1 V = 13.5 V 5.0
Output Current Limit IQ versus Input Voltage VI
500
IQ
mA 400
Tj = 25 C
300
4.9
200
4.8
4.7
100
4.6 -40
0
0 40 80 120 C 160 Tj
0
10
20
30
40 V 50 VI
Rev. 00
17
ILE 4278
Package Outlines P-DSO-14-8
Rev. 00
18

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