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L4938E/ED L4938EPD
ADVANCED VOLTAGE REGULATOR
ENABLE AND SENSE INPUTS (EN, SI) PROTECTED AGAINST NEGATIVE TRANSIENTS DOWN TO -5V RESET THRESHOLD ADJUSTABLE FROM 3.8 TO 4.7V EXTREMELY LOW QUIESCENT CURRENT, 65A (LESS THAN 90A) IN STANDBY MODE OPERATING DC SUPPLY VOLTAGE RANGE 5V - 28V OPERATING TRANSIENT SUPPLY VOLTAGE UP TO 40V HIGH PRECISION STANDBY OUTPUT VOLTAGE 5V 1% WITH 100mA CURRENT CAPABILITY OUTPUT 2 VOLTAGE 5V 2% WITH 400mA CURRENT CAPABILITY (ADJ WIRED TO VOUT2) OUTPUT 2 VOLTAGE ADJUSTABLE BY EXTERNAL VOLTAGE DIVIDER OUTPUT 2 DISABLE FUNCTION FOR STANDBY MODE PIN CONNECTIONS
DIP (12+2+2)
SO20 (12+4+4)
PowerSO20
ORDERING NUMBERS: L4938E (DIP) L4938ED (SO) L4938EPD (PSO)
DESCRIPTION The L4938E/ED/EPD is a monolithic integrated dual voltage regulator with two very low dropout outputs and additional functions as power-on reset and input voltage sense. It is designed for supplying the microcomputer controlled systems especially in automotive applications.
PR
1 2 3 4 5 6 7 8 9 10
D94AT076A
20 19 18 17 16 15 14 13 12 11
SI VS1 VS2 GND GND GND GND N.C. OUT2 ADJ
PR CT EN GND GND RES SO OUT1
1 2 3 4 5 6 7 8
D94AT075A
16 15 14 13 12 11 10 9
SI VS1 VS2 GND GND N.C. OUT2 ADJ
GND N.C. VS2 VS1 SI PR CT EN N.C. GND
1 2 3 4 5 6 7 8 9 10
L4938EPD
20 19 18 17 16 15 14 13 12 11
GND N.C. OUT2 ADJ OUT1 SO RESET N.C. N.C. GND
CT EN GND GND GND GND RES SO OUT1
DIP (12+2+2)
SO (12+4+4)
PowerSO20
February 1999
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ABSOLUTE MAXIMUM RATINGS
Symbol VINDC V INTR IO VSI ISI V EN IEN VRES , VSO IRES , ISO PO Tstg Tj TJSD Parameter DC Operating Supply Voltage Transient Operating Supply Voltage (T < 400ms) Output Current Sense Input Voltage (Voltage Forced) (note 2) Sense Input Current (Current Forced) (note 2) Enable Input Voltage (Voltage Forced) (note 2) Sense Input Current (Current Forced) (note 2) Output Voltages Output Currents (Output Low) Power Dissipation at Tamb = 80C (note 3) Powerdip 12+2+2 Storage Temperature Operating Junction Temperature Thermal shutdown junction temperature Output 2 will shut-down typically at Tj 10K lower than output 1 Value 28 -14 to 40 internally limited -20 to 20 1 -20 to 20 1 -0.3 to 20 5 875 -65 to 150 -40 to 150 165 Unit V V V mA V mA V mA mW C C 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 2 Note 3: Typical value soldered on a PC board with 8cm copper ground plane (35mm thick).
BLOCK DIAGRAM
VS1
OUT1
1.23V REG1 VS2
REFERENCE
OUT2 ADJ
EN REG2
1.23V
1.23V
CT RES
PR RESET
1.4V
SI 1.23V SENSE
D94AT074A
SO
GND
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THERMAL DATA
Symbol Rth j-amb Rth j-case Parameter Thermal Resistance Junction to ambient Thermal Resistance Junction to case
2
DIP 12+2+2 SO 12+4+4 PowerSO20 40 50 <2
Unit C/W C/W
Note 3: Typical value soldered on a PC board with 8cm copper ground plane (35mm thick).
PIN FUNCTIONS
PIN (DIP 12+2+2) 14 15 16 1 2 3 4, 5, 12, 13 6 7 8 9 10 11 PIN (SO 12+4+4) 18 19 20 1 2 3 4, 5, 6, 7, 14, 15, 16, 17 8 9 10 11 12 13 PIN PowerSO20 3 4 5 6 7 8 1,10,11,20 14 15 16 17 18 2,9,19 Name VS2 VS1 S1 PR CT EN GND RES SO OUT 1 ADJ OUT 2 NC Function Supply Voltage (400mA Regulator) Supply Voltage (100mA Regulator, Reset, Sense) Sense Input Reset Theresold Programming Reset Delay Capacitor Enable (low will activate the 400mA regulator) Ground Reset Output Sense Output 100mA Regulator Output Feedback of 400mA Regulator 400mA Regulator Output Not Connected
ELECTRICAL CHARACTERISTICS (VS = 14V; Tj = -40 to 150C unless otherwise specified.)
Symbol Parameter Supply Output Voltage Test Condition VS = 6 to 28V; IO1 = 400A to 100mA Tj 125C; IO1 = 50 to 400A IOUT1 = 10mA IOUT1 = 100mA; VS = 4.8V IOUT1 = 1 to 100mA (after regulation setting) VOUT1 = 0.8 to 4.5V IEN 2.4V (output 2 disabled) IO1 = 0.1mA; VSI > 1.3V TJ < 85C; R PR = 0 Enable = LOW; VS = 6 to 28V; I02 = 5 to 400mA IOUT2 = 100mA IOUT2 = 400mA; VS = 4.8V IOUT1 = 5 to 400mA (after regulation setting) V02 = 0.8 to 4.5V IOUT1 = 100mA; IOUT2 = 400mA VS = 6 to 28V; IO1 = 1mA, IO2 = 5mA, (after regulation setting) Min. 4.9 4.8 Typ. 5 5 0.1 0.2 Max. 5.1 5.2 0.2 0.4 25 400 90 Unit V V V V mV mA A A 5.1 0.2 0.3 0.3 0.6 50 150 1300 20 20 V V V mV mA mA mA mV
OUT 1
V O1
VDP1 VOL01 VLIM1 IQSB
Dropoutput Voltage 1 Load Regulation 1 Current Limit 1 Quiescent Current in Standby Mode
100
200 65 75
OUT 2
V O2 VDP2 VOL02 RADJ ILIM2 IQ VOLi 1,2 Output Voltage 2 ADJ connected to OUT 2 Dropoutput Voltage 2 Load Regulation 2 Adjust Input Resistance Current Limit 2 Quiescent Current Line Regulation 4.9
60 450
100 650
OUT1, OUT 2
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ELECTRICAL CHARACTERISTICS (Continued)
Symbol Parameter Test Condition Min. Typ. Max. Unit
ENABLE INPUT
VENL VENH VENhyst IEN LOW IEN HIGH Enable Input Low Voltage (Output 2 Active) Enable Input High Voltage Enable Hysteresis Enable Input Current Low Enable Input Current High VEN = 0 VEN = 1.1 to 7V; TJ < 130C; VEN = 1.1 to 7V; TJ = 130 to 150C; -20 1.4 20 -20 -1 -10 30 -8 0 0 1 20 60 -3 1 10 V V mV A A A
RESET CIRCUIT
V RT VRTH tRD min tRD nom tRR ICT ICT VRESL VRESH Reset Theresold Voltage (note4) Reset Theresold Hysteresis Reset Pulse Delay Reset Pulse Delay Reset Reaction Time Pull Down Capability of the Discharge circuit Charge Current Reset Output Low Voltage Reset Output High Leakage current R PR = R PR = 0 R PR = C RES = 47nF; t r 30s; (note 5) C RES = 47nF; (note 6) C RES = 47nF VOUT1 < VRT VOUT1 > VRT RRES = 10K to VOUT1 VOUT1 1.5V VRES = 5V 4.5 3.65 30 40 60 10 3 -1.3 VO1-0.3 VO1-0.2 3.8 60 60 100 50 6 -1 3.95 120 100 140 150 15 0.7 0.4 1 V V mV ms ms s mA A V A
SENSE COMPARATOR
VSI VSIT VSITH VSOL ISOH ISI HIGH ISI LOW Functional Range Sense Threshold Voltage Sense Threshold Hysteresis Sense Output Low Voltage Sense Output Leakage Sense Input Current High Sense Input Current Low V SI 1.05V; RSO =10K connected to 5V; VS 5V VSO = 5V; VSI 1.5V VSI = 1.1 to 7V; TJ <130C VSI = 1.1 to 7V; TJ <130 to 150C VSI = 0V -1 -10 -20 0 0 -8 Falling Edge; TJ <130C Falling Edge; TJ <130 to 150C -20 1.08 1.05 10 1.16 1.16 30 20 1.24 1.29 60 0.4 1 1 10 -3 V V V mV V A A A 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 VOUT1 exceeding VRT 6) This is the nominal reset time depending on the discharging limit of CT (saturation voltage) and theupper threshold of the timer comparator. Delay time starts with VOUT1 exceeding VRT 7) The leakage of CT must be less than 0.5mA (2V). If an external resistor between CT and VOUT1 is applied, the leakage current may be increased. The external resistor should have more than 30K. for stability: Cs 1F, C01 10F, C02 10F, 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.
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Figure 1. Application Diagram.
VS1 CS 1.23V REG1 (Note 8) 100K 15V EN REG2 1.23V REFERENCE
OUT1 CO1
OUT2 VS2 ADJ CO2
for example BZX97C15 PR
1.23V
CT
CT (Note 7)
RES VOUT1 RESET SI 1.4V SO RSO
1.23V SENSE
D94AT079A
GND
FUNCTIONAL DESCRIPTION The L4938E/ED/EPD is a monolithic integrated dual voltage regulator, based on the STM modulator voltage regulator approach. Several outstanding features and auxiliary functions are implemented to meet the requirements of supplying microprocessor systems in automotive applications. Nevertheless, it is suitable also in other applications where two stabilized voltages are required. The modular approach of this device allows to get easly also other features and functions 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 voltage is regulated up to the transient input supply voltage of 40V. With this feature no functional interruption due to overvoltage pulses is generated. In the standby mode when the output 2 is disabled, the current consumption of the device (quiescent current) is less than 90A (14V supply voltage).
To reduce the quiescent current peak in the undervoltage region and to improve the transient response in this region, the dropout voltage is controlled. 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 VOUT2. The output 2 regulator can be switches OFF via the enable input. Figure 2.
OUT2 R1E R2E RADJ R2i total 100K typical
D94AT080
ADJ R1i + 1.23V
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L4938E - L4938ED - L4938EPD
Connecting a resistor divider R1E, R2E to the ADJ, OUT2 pin the output voltage 2 can be programmed to the value of R1E(R2E + RADJ) VOUT2 = VOUT1 1 + R2E RADJ with RADJ = 60K to 150K and VOUT1 = 4.95 to 5.05V. For an exact calculation the temperature coefficient (Tc -2000pprm) of the internal resistor (RADJ) must be taken into account. Pin ADJ in this mode should not have a capacitive burden because this would reduce the phase margin of the regulator loop. Reset circuit The reset circuit supervises the standby output voltage. The reset output (RES) is defined from VOUT 1V. Even if VS is lacking, the reset generator is supplied by the output voltage V OUT1. The reset threshold of 4.7V is defined with the internal reference voltage (note 9) and standby output divider, when pin PR is left open. The reset threshold voltage can be programmed in the range from 3.8V to 4.7V by connecting an external resistor from pin PR to GND. The value of the programming resistor RPR can be calculated with: RPR = 22K - 92.9K,3.8V VRT 4.7V 4.7K -1 VRT than approximately 50s. The minimum rset time is generated if reset condition only occures for a short time triggering a reset pulse but not completely discharging CT. The reset can be related to output2 on request. If higher charge currents for the reset capacitor are required a resistors from Pin CT to OUT1, may be used to increase the current. We recommended the use of 10K to 5V as an output pull up. Sense Comparator The sense comparator compares an input signal with an internal voltage reference of typical 1.23V. The use of an external voltage divider makes this comparator very flexible in the application. It can be used to supervise the input voltage either before or after the protection diode and to give additional information to the microprocessor like low voltage warnings. We recommended the use of 10K to 5V as an output pull up.
Note 9: The reference is alternatively supplied from VS or VOUT1. If one supply is present, the reference is operating.
The reset pulse delay time t RD, is defined with the charge time of an external capacitor CT: CT 0.6V (note 5) tRDmin = 1A tRDnom = CT 1.4V (note 6) 1A
Thermal Protection Both outputs are provided with an overtemperature shut down regulation power dissipation down to uncritical values. Output 2 will shut down approximately 10K before output 1. Under normal conditions shut down of output 2 will allow the chip to cool down again. Thus output 1 will be unaffected. The thermal shut down reduces the output voltages until power dissipation and the flow of thermal energy out of the chip balance. Transient Sensitivity In proper operation (VOUT > 4.5V) the reference is supplied by V OUT1 thus reducing sensitivity to input transients. Precise Data will be issued as soon as samples are available.
The reaction time of the reset circuit originates from the noise immunity. Standby output voltage drops below the reset threshold only a bit longer than the reaction time results in a shorter reset delay time. The nominal reset delay time will be generated for standby output voltage drops longer
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Figure 3. Reset Generator
OUT1 REF 1.23V 1A 17K PR VOUT1 REG 74K + RES
10...100K
Low threshold VBE at 1A=0.5V at 25C High threshold CT CT
D94AT081
=1.4
Figure 4:
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L4938E - L4938ED - L4938EPD
INPUT PROTECTION The Inputs Enable (EN) and sense in(SI) are proFigure 5. tected against negative transients. Figure 5 is showing the simplified schematic
Input Characteristics of SI, EN:
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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 0.050
Powerdip 16
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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
mm TYP. MAX. 2.65 0.3 0.51 0.32 13 7.6 1.27 10.65 0.75 1.27 0.394 0.010 0.016 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
10/12
L4938E - L4938ED - L4938EPD
mm TYP. inch TYP.
DIM. A a1 a2 a3 b c D (1) D1 E e e3 E1 (1) E2 E3 G H h L N S T
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
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L4938E - L4938ED - L4938EPD
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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