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Электронный компонент: L4938E

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L4938E/ED
L4938EPD
ADVANCED VOLTAGE REGULATOR
ENABLE AND SENSE INPUTS (EN, SI) PRO-
TECTED AGAINST NEGATIVE TRANSIENTS
DOWN TO -5V
RESET THRESHOLD ADJUSTABLE FROM
3.8 TO 4.7V
EXTREMELY LOW QUIESCENT CURRENT,
65
A (LESS THAN 90
A) IN STANDBY
MODE
OPERATING DC SUPPLY VOLTAGE RANGE
5V - 28V
OPERATING TRANSIENT SUPPLY VOLT-
AGE UP TO 40V
HIGH PRECISION STANDBY OUTPUT VOLT-
AGE 5V
1% WITH 100mA CURRENT CA-
PABILITY
OUTPUT 2 VOLTAGE 5V
2% WITH 400mA
CURRENT CAPABILITY (ADJ WIRED TO
V
OUT2
)
OUTPUT 2 VOLTAGE ADJUSTABLE BY EX-
TERNAL VOLTAGE DIVIDER
OUTPUT
2
DISABLE
FUNCTION
FOR
STANDBY MODE
DESCRIPTION
The L4938E/ED/EPD is a monolithic integrated
dual voltage regulator with two very low dropout
outputs and additional functions as power-on re-
set and input voltage sense. It is designed for
supplying the microcomputer controlled systems
especially in automotive applications.
February 1999
PIN CONNECTIONS
DIP (12+2+2)
SO20 (12+4+4)
PowerSO20
ORDERING NUMBERS: L4938E (DIP)
L4938ED (SO)
L4938EPD (PSO)
PR
CT
EN
GND
GND
SO
RES
1
3
2
4
5
6
7
OUT2
GND
N.C.
GND
VS2
VS1
SI
16
15
14
13
12
10
11
D94AT075A
OUT1
8
ADJ
9
DIP (12+2+2)
PR
CT
EN
GND
GND
GND
GND
RES
SO
OUT2
N.C.
GND
GND
GND
GND
VS2
VS1
SI
1
3
2
4
5
6
7
8
9
18
17
16
15
14
12
13
11
19
10
20
OUT1
ADJ
D94AT076A
SO (12+4+4)
GND
N.C.
N.C.
V
S2
V
S1
PR
SI
CT
EN
N.C.
GND
10
8
9
7
6
5
4
3
2
13
14
15
16
17
19
18
20
12
1
11
GND
L4938EPD
N.C.
RESET
OUT1
SO
ADJ
OUT2
N.C.
GND
PowerSO20
1/12
REG1
1.23V
REFERENCE
REG2
1.23V
RESET
1.4V
1.23V
1.23V
SENSE
VS1
VS2
EN
PR
SI
SO
RES
CT
ADJ
OUT2
OUT1
GND
D94AT074A
BLOCK DIAGRAM
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Value
Unit
V
INDC
DC Operating Supply Voltage
28
V
V
INTR
Transient Operating Supply Voltage (T < 400ms)
-14 to 40
V
I
O
Output Current
internally limited
V
SI
Sense Input Voltage (Voltage Forced) (note 2)
-20 to 20
V
I
SI
Sense Input Current (Current Forced) (note 2)
1
mA
V
EN
Enable Input Voltage (Voltage Forced) (note 2)
-20 to 20
V
I
EN
Sense Input Current (Current Forced) (note 2)
1
mA
V
RES
, V
SO
Output Voltages
-0.3 to 20
V
I
RES
, I
SO
Output Currents (Output Low)
5
mA
P
O
Power Dissipation at T
amb
= 80
C (note 3)
Powerdip 12+2+2
875
mW
T
stg
Storage Temperature
-65 to 150
C
T
j
Operating Junction Temperature
-40 to 150
C
T
JSD
Thermal shutdown junction temperature Output 2 will shut-down
typically at Tj 10K lower than output 1
165
C
Note 1:
The circuit is ESD protected according to MIL-STD-883C
Note 2: Current forced means voltage unlimited but current limited to the specified value
Voltage forced means voltage limi ted to the specified valueswhile the current is not limited
Note 3: Typical value soldered on a PC board with 8cm
2
copper ground plane (35mm thick).
L4938E - L4938ED - L4938EPD
2/12
ELECTRICAL CHARACTERISTICS (V
S
= 14V; T
j
= -40 to 150
C unless otherwise specified.)
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
OUT 1
V
O1
Supply Output Voltage
V
S
= 6 to 28V;
I
O1
= 400
A to 100mA
4.9
5
5.1
V
T
j
125
C; I
O1
= 50 to 400
A
4.8
5
5.2
V
V
DP1
Dropoutput Voltage 1
I
OUT1
= 10mA
0.1
0.2
V
I
OUT1
= 100mA; V
S
= 4.8V
0.2
0.4
V
V
OL01
Load Regulation 1
I
OUT1
= 1 to 100mA
(after regulation setting)
25
mV
V
LIM1
Current Limit 1
VOUT1 = 0.8 to 4.5V
100
200
400
mA
I
QSB
Quiescent Current in Standby
Mode
I
EN
2.4V (output 2 disabled)
I
O1
= 0.1mA; V
SI
> 1.3V
65
90
A
T
J
< 85
C; R
PR
= 0
75
A
OUT 2
V
O2
Output Voltage 2
ADJ connected to OUT 2
Enable = LOW; V
S
= 6 to 28V;
I
02
= 5 to 400mA
4.9
5.1
V
V
DP2
Dropoutput Voltage 2
I
OUT2
= 100mA
0.2
0.3
V
I
OUT2
= 400mA; V
S
= 4.8V
0.3
0.6
V
V
OL02
Load Regulation 2
I
OUT1
= 5 to 400mA
(after regulation setting)
50
mV
R
ADJ
Adjust Input Resistance
60
100
150
mA
I
LIM2
Current Limit 2
V02 = 0.8 to 4.5V
450
650
1300
mA
I
Q
Quiescent Current
I
OUT1
= 100mA; I
OUT2
= 400mA
20
mA
OUT1, OUT 2
V
OLi 1,2
Line Regulation
V
S
= 6 to 28V; I
O1
= 1mA,
I
O2
= 5mA,
(after regulation setting)
20
mV
PIN FUNCTIONS
PIN
(DIP 12+2+2)
PIN
(SO 12+4+4)
PIN
PowerSO20
Name
Function
14
18
3
VS2
Supply Voltage (400mA Regulator)
15
19
4
VS1
Supply Voltage (100mA Regulator, Reset, Sense)
16
20
5
S1
Sense Input
1
1
6
PR
Reset Theresold Programming
2
2
7
CT
Reset Delay Capacitor
3
3
8
EN
Enable (low will activate the 400mA regulator)
4, 5, 12, 13
4, 5, 6, 7, 14,
15, 16, 17
1,10,11,20
GND
Ground
6
8
14
RES
Reset Output
7
9
15
SO
Sense Output
8
10
16
OUT 1
100mA Regulator Output
9
11
17
ADJ
Feedback of 400mA Regulator
10
12
18
OUT 2
400mA Regulator Output
11
13
2,9,19
NC
Not Connected
THERMAL DATA
Symbol
Parameter
DIP 12+2+2 SO 12+4+4 PowerSO20
Unit
R
th j-amb
Thermal Resistance Junction to ambient
40
50
-
C/W
R
th j-case
Thermal Resistance Junction to case
-
-
<2
C/W
Note 3: Typical value soldered on a PC board with 8cm
2
copper ground plane (35mm thick).
L4938E - L4938ED - L4938EPD
3/12
ELECTRICAL CHARACTERISTICS (Continued)
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
ENABLE INPUT
V
ENL
Enable Input Low Voltage
(Output 2 Active)
-20
1
V
V
ENH
Enable Input High Voltage
1.4
20
V
V
ENhyst
Enable Hysteresis
20
30
60
mV
I
EN LOW
Enable Input Current Low
V
EN
= 0
-20
-8
-3
A
I
EN HIGH
Enable Input Current High
V
EN
= 1.1 to 7V; T
J
< 130
C;
-1
0
1
A
V
EN
= 1.1 to 7V;
T
J
= 130 to 150
C;
-10
0
10
A
RESET CIRCUIT
V
RT
Reset Theresold Voltage
(note4)
R
PR
=
4.5
V
O1
-0.3 V
O1
-0.2
V
R
PR
= 0
3.65
3.8
3.95
V
V
RTH
Reset Theresold Hysteresis
R
PR
=
30
60
120
mV
t
RD min
Reset Pulse Delay
C
RES
= 47nF; t
r
30
s; (note 5)
40
60
100
ms
t
RD nom
Reset Pulse Delay
C
RES
= 47nF; (note 6)
60
100
140
ms
t
RR
Reset Reaction Time
C
RES
= 47nF
10
50
150
s
I
CT
Pull Down Capability of the
Discharge circuit
V
OUT1
< V
RT
3
6
15
mA
I
CT
Charge Current
V
OUT1
> V
RT
-1.3
-1
0.7
A
V
RESL
Reset Output Low Voltage
R
RES
= 10K
to V
OUT1
V
OUT1
1.5V
0.4
V
V
RESH
Reset Output High Leakage
current
V
RES
= 5V
1
A
SENSE COMPARATOR
V
SI
Functional Range
-20
20
V
V
SIT
Sense Threshold Voltage
Falling Edge; T
J
<130
C
1.08
1.16
1.24
V
Falling Edge; T
J
<130
to 150
C
1.05
1.16
1.29
V
V
SITH
Sense Threshold Hysteresis
10
30
60
mV
V
SOL
Sense Output Low Voltage
V
SI
1.05V; R
SO
=10K
connected to 5V; V
S
5V
0.4
V
I
SOH
Sense Output Leakage
V
SO
= 5V; V
SI
1.5V
1
A
I
SI HIGH
Sense Input Current High
V
SI
= 1.1 to 7V; T
J
<130
C
-1
0
1
A
V
SI
= 1.1 to 7V; T
J
<130
to 150
C
-10
0
10
A
I
SI LOW
Sense Input Current Low
V
SI
= 0V
-20
-8
-3
A
Note :
4) The reset threshold can be programmed continuously from typ 3.8V to 4.7V by changing a value of an external resistor from pin PR to GN
5) This is a minimum reset time according to the hysteresis of the comparator. Delay time starts with V
OUT1
exceeding V
RT
6) This is the nominal reset time depending on the discharging limit of C
T
(saturation voltage) and theupper threshold of the timer comparator.
Delay time starts with V
OUT1
exceeding V
RT
7) The leakage of C
T
must be less than 0.5mA (2V). If an external resistor between C
T
and V
OUT1
is applied, the leakage current may be
increased. The external resistor should have more than 30K
.
for stability: Cs
1
F, C01
10
F, C02
10
F, ESR
5
(designed target) For details see application note.
8) For transients exceeding 20V or -20V external protection is required at the Pins SI and EN as shown at Pin EN. The protection proposed will
provide proper function for transients in the range of
200V. If the zener diode is omitted the external resistor should be raised to 200K
to limit the current to 1mA. Without the zener diode, the function 20V or -20V can not be guaran teed.
L4938E - L4938ED - L4938EPD
4/12
FUNCTIONAL DESCRIPTION
The L4938E/ED/EPD is a monolithic integrated
dual voltage regulator, based on the STM modu-
lator voltage regulator approach. Several out-
standing features and auxiliary functions are im-
plemented to meet the requirements of supplying
microprocessor systems in automotive applica-
tions. Nevertheless, it is suitable also in other ap-
plications where two stabilized voltages are re-
quired. The modular approach of this device
allows to get easly also other features and func-
tions when required.
Standby Regulator
The standby regulator uses an Isolated collector
Vertical PNP transistor as a regulating element.
With this structure very low dropout volotage at
currents up to 100mA is obtained. The dropout
operation of the standby regulator is maintained
down to 3V input supply voltage. The output volt-
age is regulated up to the transient input supply
voltage of 40V. With this feature no functional in-
terruption due to overvoltage pulses is generated.
In the standby mode when the output 2 is dis-
abled, the current consumption of the device (qui-
escent current) is less than 90
A (14V supply
voltage).
To reduce the quiescent current peak in the un-
dervoltage region and to improve the transient re-
sponse in this region, the dropout voltage is con-
trolled. A second regulation path will keep the
output voltage without load below 5.5V even at
high temperatures.
Output 2 Voltage
The output 2 regulator uses the same output
structure as the standby regulator but rated for
the output current of 400mA. The output voltage
is internally fixed to 5V if ADJ is connected to
V
OUT2
.
The output 2 regulator can be switches OFF via
the enable input.
REG1
1.23V
REFERENCE
REG2
1.23V
RESET
1.4V
1.23V
1.23V
SENSE
VS1
VS2
EN
PR
SI
SO
RES
CT
ADJ
OUT2
OUT1
GND
D94AT079A
15V
100K
C
S
(Note 8)
for example
BZX97C15
CT (Note 7)
C
O2
C
O1
V
OUT1
R
SO
Figure 1. Application Diagram.
1.23V
D94AT080
-
+
R
1i
R
2i
OUT2
ADJ
R
1E
R
2E
R
ADJ
total 100K
typical
Figure 2.
L4938E - L4938ED - L4938EPD
5/12