L4938N STMicroelectronics, L4938N Datasheet - Page 5

• Manufacturer Part Number: L4938N
• Description: Linear Regulators - Standard Dual 5V Very LDO
• Manufacturer: STMicroelectronics

Specifications of L4938N

• Polarity: Positive
• Number Of Outputs: 2
• Output Type: Selectable
• Output Voltage: 5 V
• Output Current: 5 mA
• Line Regulation: 20 mV
• Load Regulation: 50 mV
• Dropout Voltage (max): 0.4 V
• Input Voltage Max: 28 V
• Maximum Operating Temperature: + 150 C
• Minimum Operating Temperature: - 55 C
• Package / Case: PDIP-16
• Maximum Power Dissipation: 875 mW
• Mounting Style: Through Hole
• Reference Voltage: 1.23 V
• Voltage Regulation Accuracy: 2 %
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

ELECTRICAL CHARACTERISTICS (continued)
RESET
SENSE
Note : 1 : V
FUNCTIONAL DESCRIPTION
The L4938N is based on the STMicroelectronics
modular voltage regulator approach. Several out-
standing features and auxiliary functions are pro-
vided to meet the requirements of supplying the mi-
croprocessor systems used in automotive applica-
tions.
Furthermore the device is suitable also in other ap-
plications requiring two stabilized voltages.
The modular approach allows other features and
functions to be realized easily when required.
STANDBY REGULATOR
The standby regulator uses an Isolated Collector
Vertical PNP transistor as the regulating element.
This structure allows a very low dropout voltage at
currents up to 50mA. The dropout operation of the
standby regulator is maintained down to 2V input
supply voltage. The output voltage is regulated up
to the transient input supply voltage of 40V. This fea-
ture avoids functional interruptions which could be
generated by overvoltage pulses.
The typical curve of the standby output voltage as a
function of the input supply voltage is shown in fig. 1.
V
Symbol
V
CTh, hyst
I
Slth, hyst
V
V
V
V
I
V
LRES
V
t
t
LSO
RD
RR
CTh
SOL
Slth
Rth
RL
Rt
2 : Foldback characteristic
O2
Reset Low Threshold Voltage
Reset Threshold Hysteresis
Reset Pulse Delay
Reset Reaction Time
Reset Output LOW Voltage
Reset Output HIGH Leakage
Delay Comparator Threshold
Delay Comparator Threshold
Hysteresis
Sense Threshold Voltage
Sense Threshold Hysteresis
Sense Output LOW Voltage
Sense Output Leakage
connected to ADJ.V
Parameter
O2
can be set to higher values by inserting an external resistor divider.
C
C
R
V
V
V
R
V
S
RES
SI
SO
T
T
RES
SO
= 100nF; t
= 100nF
= 1.5V
= 1,16V; V
= 5V; V
= 10K to V
= 10K to V
= 5V
Test Conditions
SI
R
S
The current consumption of the device (quiescent
current) is less than 250 A when output 2 is dis-
abled (standby mode). The dropout voltage is con-
trolled to reduce the quiescent current peak in the
undervoltage region and to improve the transient
response in this region.
The quiescent current is shown in fig. 2 as a function
of the supply input voltage 2.
OUTPUT 2 VOLTAGE
The output 2 regulator uses the same output struc-
ture as the standby regulator, but rated for an output
current of 500mA.
The output 2 regulator works in tracking mode with
the standby output voltage as a reference voltage
when the output 2 programming pin ADJ is con-
nected to V
R
age 2 can be programmed to the value :
The output 2 regulator can be switched off via the
Enable input.
If a fixed 5 regulation is required ADJ Pin has to be
connected to V
> 100 s
1.5V
2
01
3V
01
to the pin ADJ as shown in fig. 3, the output volt-
O2
L4938N - L4938ND - L4938NPD
. By connecting a resistor divider R
V
02
O2
Pin.
V
= V
o1
Min.
1.16
50
55
40
1
-0.4
O1
(1 + R
Typ.
1.23
100
100
100
100
4.7
2.0
10
1
/R
2
V
)
Max.
o1
1.35
200
180
200
0.4
0.4
50
1
1
-0.1
Unit
mV
mV
mV
mV
V
V
V
V
V
A
A
s
5/12
1
,