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L4938N/ND L4938NPD
DUAL MULTIFUNCTION VOLTAGE REGULATOR
.STANDBY .OUTPUT .OUTPUT .VERY .OUTPUT .OUTPUT .VERY .OPERATI .POWER.POWER.EARLY .THERMAL
2% PUT
OUTPUT VOLTAGE PRECISION 5V
2 TRACKED TO THE STANDBY OUT-
2 DISABLE FUNCTION FOR STANDBY MODE LOW QUIESCENT CURRENT, LESS THAN 250A, IN STANDBY MODE 2 VOLTAGE SETTABLE FROM 5 TO 20V CURRENTS : I01 = 50mA, I02 = 500mA LOW DROPOUT (max 0.4V/0.6V) NG TRANSIENT SUPPLY VOLTAGE UP TO 40V ON RESET CIRCUIT SENSING THE STANDBY OUTPUT VOLTAGE ON RESET DELAY PULSE DEFINED BY THE EXTERNAL CAPACITOR WARNING OUTPUT FOR SUPPLY UNDERVOLTAGE SHUTDOWN AND SHORT CIRCUIT PROTECTIONS
PowerDIP (12+2+2)
SO20 (12+4+4)
PowerSO20
ORDERING NUMBERS: L4938N (PDIP) L4938ND (SO) L4938NPD (PSO20)
DESCRIPTION The L4938N is a monolithic integrated dual voltage regulators with two very low dropout outputs and additional functions such as power-on reset and input voltage sense. They are designed for supplying microcomputer controlled systems specially in automotive applications.
PIN CONNECTION (top view)
POWERDIP
SO20
PowerSO20
N.C.
1 2 3 4 5 6 7 8 9 10
D93AT004
20 19 18 17 16 15 14 13 12 11
SI VS1 VS2 GND GND GND GND VO2 VO2 ADJ
N.C. CT EN GND GND RES SO VO1
1 2 3 4 5 6 7 8
D95AT156
16 15 14 13 12 11 10 9
SI VS1 VS2 GND GND VO2 VO2 ADJ
GND N.C. VS2 VS1 SI N.C. CT EN N.C. GND
1 2 3 4 5 6 7 8 9 10
D95AT169A
20 19 18 17 16 15 14 13 12 11
GND N.C. VO2 ADJ VO1 SO RESET N.C. N.C. GND
C7 EN GND GND GND GND RES SO VO1
April 1999
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This is advanced information on a new product now in development or undergoing evaluation. Details are subject to change without notice.
L4938N - L4938ND - L4938NPD
BLOCK DIAGRAM
VS1
VO1
REFERENCE
1.23V REG1 VO2
VS2 EN REG2
ADJ
1.23V 2
CT RES
RESET
2.0V
SI SENSE (optional) 1.23V
SO
GND
D94AT143A
THERMAL DATA
Symbol Rthj-case Rthj-amb Parameter Thermal Resistance Junction-Case Thermal Resistance Junction-Ambient Max. Max. Powerdip 14 90 PowerSO20 <2 - SO20 - 20 Unit C/W C/W
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ABSOLUTE MAXIMUM RATINGS
Symbol VS Tj, Tstg ISI IEN VEN VRES, VSO IRES, ISO PD DC Supply Voltage Transient Supply Voltage (T < 1s) Junction and Storage Temperature Range Sense Input Current (VSI 0.3V or VSI > VS) Enable Input Current (VEN 0.3V) Enable Input Voltage Reset and Sense Output Voltage Reset and Sense Output Current Power Dissipation Parameter Value 28 40 -55 to 150 1 1 VS 20 5 875 V mA mW Unit V V C mA mA
Note : The circuit is ESD protected according to MIL-STD-883C.
APPLICATION CIRCUIT
VS1 CS
VO1 CO1
REFERENCE
1.23V REG1 VO2
VS2 EN REG2
ADJ CO2
1.23V 2
CT RES
CT
RRES RESET SI 2.0V RSO SO SENSE (optional) 1.23V VO1
GND
D94AT144A
CS 1F ; C01 6F ; C02 10F, ESR < 10 at 10KHz
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L4938N - L4938ND - L4938NPD
ELECTRICAL CHARACTERISTICS (VS = 14V; -40C TJ 125C unless otherwise specified)
Symbol VS VO1 VO2 - VO1 Parameter Operating Supply Voltage Standby Output Voltage Output Voltage 2 Tracking Error (note 1) ADJ Input Current Dropout Voltage 1 Input to Output Voltage Difference in Undervoltage Condition Dropout Voltage 2 Input to Output Voltage Difference in Undervoltage Condition Line Regulation Load Regulation 1 Load Regulation 2 Current Limit 1 Current Limit 2 6V VS 25V 1mA IO1 50mA 6V VS 25V 5mA IO2 500mA Enable = LOW IO1 = 1mA; IO2 = 5mA IO1 = 10mA IO1 = 50mA VS = 4V, IO1 = 35mA 4.90 -25 5.00 Test Conditions Min. Typ. Max. 25 5.10 +25 Unit V V mV
IADJ VDP1 VIO1
-1
0.1 0.1 0.2
1 0.25 0.4 0.4
A V V V
VDP2 VIO2
IO1 = 100mA IO1 = 500mA VS = 4.6V, IO1 = 350mA
0.2 0.3
0.3 0.6 0.6
V V V
VOL 1.2 VOLO1 VOLO2 ILIM1 ILIM2 IQSB
6V VS 25V IO1 = 1mA; IO2 = 5mA 1mA IO1 50mA 5mA IO2 500mA VO1 = 4.5V VO1 = 0V (note 2) VO2 = 0V 55 25 550 100 50 1000
20 25 50 200 100 1700
mV mV mV mA mA mA
Quiescent Current Standby Mode IO1 = 0.3mA; TJ < 100C (output 2 disabled) VEN 2.4V VS = 14V VS = 3.5V Quiescent Current IO1 = 50mA IO1 = 500mA
210 340
290 850 30
A A mA
IQ
ENABLE
VENL VENH VENhyst IEN Enable Input LOW Voltage (output 2 active) Enable Input HIGH Voltage Enable Hysteresis Enable Input Current 0V < VEN < 1.2V 2.5V < VEN < 7V -0.3 2.4 30 -10 -1 75 -1.5 0 1.5 7 200 -0.5 +1 V V mV A A
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L4938N - L4938ND - L4938NPD
ELECTRICAL CHARACTERISTICS (continued) RESET
Symbol VRt VRth tRD tRR VRL ILRES VCTh VCTh, hyst Parameter 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 CT = 100nF; tR > 100s CT = 100nF RRES = 10K to V01 VS = 1.5V VRES = 5V 2.0 100 Test Conditions Min. Vo1 -0.4 50 55 1 Typ. 4.7 100 100 10 Max. Vo1 -0.1 200 180 50 0.4 1 Unit V mV mV s V A V mV
SENSE
VSlth VSlth, hyst VSOL ILSO Sense Threshold Voltage Sense Threshold Hysteresis Sense Output LOW Voltage Sense Output Leakage VSI = 1,16V; VS 3V RSO = 10K to V01 VSO = 5V; VSI 1.5V 1.16 40 1.23 100 1.35 200 0.4 1 V mV V A
Note : 1 : VO2 connected to ADJ.VO2 can be set to higher values by inserting an external resistor divider. 2 : Foldback characteristic
FUNCTIONAL DESCRIPTION The L4938N is based on the STMicroelectronics modular voltage regulator approach. Several outstanding features and auxiliary functions are provided to meet the requirements of supplying the microprocessor systems used in automotive applications. Furthermore the device is suitable also in other applications 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 feature 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.
The current consumption of the device (quiescent current) is less than 250A when output 2 is disabled (standby mode). The dropout voltage is controlled 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 structure 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 connected to VO2. By connecting a resistor divider R1, R2 to the pin ADJ as shown in fig. 3, the output voltage 2 can be programmed to the value : VO2 = VO1 (1 + R1/R2) 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 V02 Pin.
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L4938N - L4938ND - L4938NPD
Figure 1 : Output Voltage vs. Input Voltage.
Figure 2 : Quiescent Current vs. Supply Voltage.
400
200
Figure 3 : Programmable Output 2 Voltage with External Resistors.
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L4938N - L4938ND - L4938NPD
RESET CIRCUIT The block circuit diagram of the reset circuit is shown in fig. 4. The reset circuit supervises the standby output voltage. The reset threshold of 4.7V is defined by the internal reference voltage and the standby output divider. The reset pulse delay time tRD, is defined by the charge time of an external capacitor CT : CT x 2V tRD = 2A occurs. The nominal reset delay is generated for standby output voltage drops longer than the time necessary for the complete discharging of the capacitor CT. This time is typically equal to 50s if CT = 100nF. The typical reset output waveforms are shown in fig. 5. SENSE COMPARATOR This circuit compares an input signal with an internal voltage reference of typically 1.23V. The use of an external voltage divider makes the comparator very flexible in the application. This function can be used to supervise the input voltage - either before or after the protection diode - and to give additional information to the microprocessor such as low voltage warnings. If this feature is not used SI and SO have to connected to GND. In this case the St-by quiescent current (14V) increases from 290A to 300A.
The reaction time of the reset circuit depends on the discharge time limitation of the reset capacitor CT and is proportional to the value of CT. The reaction time of the reset circuit increases the noise immunity. In fact, if the standby output voltage drops below the reset threshold for a time shorter than the reaction time tRR, no reset output variation Figure 4: Block Diagram of the Reset Circuit.
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L4938N - L4938ND - L4938NPD
Figure 5 : Typical Reset Output Waveforms.
1.5V
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L4938N - L4938ND - L4938NPD
DIM. MIN. a1 B b b1 D E e e3 F I L Z 0.38 0.51 0.85
mm TYP. MAX. MIN. 0.020 1.40 0.50 0.50 20.0 8.80 2.54 17.78 7.10 5.10 3.30 1.27 0.015 0.033
inch TYP. MAX.
OUTLINE AND MECHANICAL DATA
0.055 0.020 0.020 0.787 0.346 0.100 0.700 0.280 0.201 0.130
Powerdip 16
0.050
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L4938N - L4938ND - L4938NPD
DIM. A a1 a2 a3 b c D (1) D1 E e e3 E1 (1) E2 E3 G H h L N S T mm TYP. inch TYP.
MIN. 0.1 0 0.4 0.23 15.8 9.4 13.9
MAX. 3.6 0.3 3.3 0.1 0.53 0.32 16 9.8 14.5
MIN. 0.004 0.000 0.016 0.009 0.622 0.370 0.547
MAX. 0.142 0.012 0.130 0.004 0.021 0.013 0.630 0.386 0.570
OUTLINE AND MECHANICAL DATA
1.27 11.43 10.9 5.8 0 15.5 0.8 11.1 0.429 2.9 6.2 0.228 0.1 0.000 15.9 0.610 1.1 1.1 0.031 10 (max.) 8 (max.) 10
0.050 0.450 0.437 0.114 0.244 0.004 0.626 0.043 0.043
JEDEC MO-166
0.394
(1) "D and F" do not include mold flash or protrusions. - Mold flash or protrusions shall not exceed 0.15 mm (0.006"). - Critical dimensions: "E", "G" and "a3"
PowerSO20
N
N a2 b e A
R
c DETAIL B a1 E DETAIL A
DETAIL A e3 H
lead
D a3 DETAIL B
20 11
Gage Plane 0.35
slug
-C-
S E2 T E1 BOTTOM VIEW
L
SEATING PLANE G C
(COPLANARITY)
E3
1 10
h x 45
PSO20MEC
D1
10/12
L4938N - L4938ND - L4938NPD
mm DIM. MIN. A A1 B C D E e H h L K 10 0.25 0.4 2.35 0.1 0.33 0.23 12.6 7.4 1.27 10.65 0.75 1.27 0.394 0.010 0.016 TYP. MAX. 2.65 0.3 0.51 0.32 13 7.6 MIN. 0.093 0.004 0.013 0.009 0.496 0.291
inch TYP. MAX. 0.104 0.012 0.020 0.013 0.512 0.299 0.050 0.419 0.030 0.050
OUTLINE AND MECHANICAL DATA
SO20
0 (min.)8 (max.)
L
h x 45
A B e K H D A1 C
20
11 E
1
0 1
SO20MEC
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L4938N - L4938ND - L4938NPD
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specification mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics (c) 1999 STMicroelectronics - Printed in Italy - All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - France - Germany - Italy - Japan - Korea - Malaysia - Malta - Mexico - Morocco - The Netherlands Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A. http://www.st.com
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