ST L4920/L4921 handbook
Contents
1. lo 400 Vo 1 2V lt Vi 26V Foldback protection Note 1 Design limits are guaranteed but not 10096 production tested over the indicated temperature and supply voltage ranges These limits are not used to calculate outgoing quality levels 4 3 7 L4920 L4921 Figure 1 Output Voltage vs Temperature ETITA LLL BB 1111111111 1111111111 1 1 40 20 0 20 40 0 80 100 Tj Figure 3 Quiescent Current vs Output Current Vo 5V 400 APPLICATION INFORMATION 1 The L4920 and L4921 have Vrer 1 25V Then the output voltage can be set downto Vrer but Vi mustbe greaterthan 5 2V Tj 25 C 2 As the regulator reference voltage source works in closed loop the reference voltage may change in foldbackcondition 3 For applications with high Vi the total power dissipation of the device with respect to the ther 4 7 Figure 2 Foldback Current Limiting 4920 01 mal resistance of the package may be limiting The total power dissipation is Ptot Vi la Vi Vo lo A typical curve giving the quiescent current ly as a function of the output current lo is shownin fig 3 4 L4920 L4921 OUTLINE AND MECHANICAL DATA PowerMinidip L4920 L4921 OUTLINE AND MECHANICAL DATA Pentawatt V z LLI gt FS ua mg Z mn LLI oc RN L4920 L4921 Information furnished is believed to b2. O D 1492010 0 ky 14920 14921 VERY LOW DROP ADJUSTABLE REGULATORS a VERY LOW DROP VOLTAGE a ADJUSTABLE OUTPUT VOLTAGE FROM 1 25V TO 20V 400mA OUTPUT CURRENT LOW QUIESCENT CURRENT REVERSE VOLTAGE PROTECTION 60 60V TRANSIENT PEAK VOLTAGE PROTECTION SHORT CIRCUIT PROTECTION WITH FOLD BACK CHARACTERISTICS a THERMAL SHUT DOWN DESCRIPTION The L4920 and L4921 are adjustable voltage regu lators with a verylow voltage drop 0 4V typ at 0 4A Tj 25 C low quiescent current and comprehen sive on chip protection Thesedevices are protectedagainstload dump and field decay transients polarity reversal and over heating A foldbackcurrentlimiter protects againstload short circuits The outputvoltage is adjustablethrough an external divider from 1 25V to 20V The minimum operating input voltage is 5 2V Ty 25 C BLOCK DIAGRAM THERMAL PROTECTION June 2000 Pentawatt Minidip 4 4 ORDERING NUMBERS L4920 Pentawatt L4921 Minidip These regulators are designed for automotive in dustrial and consumer applications where low con sumption is particularly important In battery backup and standby applications the low consumption of these devices extends battery life FOLOBACK CURRENT LIMITER 5 7918 1 7 L4920 L4921 ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit 35 Vi DC Input Operating Voltage V DC Reverse Input Vol
3. e accurate and reliable However STMicroelectronics assumes no responsibility for the conse quences 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 STMi croelectronics 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 2000 STMicroelectronics Printed in Italy All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia Brazil China Finland France Germany Hong Kong India Italy Japan Malaysia Malta Morocco Singapore Spain Sweden Switzerland United Kingdom U S A http www st com 7 7 q
4. tage Transient Input Overvoltages Load Dump 5ms lt trise lt 10ms t Fall time constant 100ms Resource gt 0 50 Field Decay 5ms x tran lt 10ms Rsource gt 100 Rise time constant 33ms Junction and Storage Temperature Range 55 to 150 PIN CONNECTIONS top view GROUND Zu connected Io pin3 TEST AND APPLICATION CIRCUIT S 79 12 C 100uF is required for stability ESR lt 3Q over T range R2 6 2KQ THERMAL DATA Parameter Minidip Pentawatt 4 4 Rthj amb Thermal Resistance Junction ambient Max 80 C W 60 C W Rin j pins Thermal Resistance Junction pins Max 15 C W Rth j case Thermal Resistance Junction case Max 3 5 C W 2 7 L4920 L4921 ELECTRICAL CHARACTERISTICS forV 14 4V TJ 25 C Vo 5V Co 100uF unless Otherwise Speci fied 3 Quiescent Current lo Vo 1V Vi 26V lo 400 Vo 1V lt V 26V Maximal Output Current Short Circuit Output Current Foldback protection 3 l3 3 gt ELECTRICAL CHARACTERISTICS for Vi 14 4V 40 x Ty x 125 C note 1 Vo 5V Co 100uF unless Otherwise Specified Parameter NEN Operating Input Voltage 1 1 Line Regulation Vo 1 2V lt Vi lt 26V Vo gt 4 5V lo 5mA Vi Load Regulation 5mA lt lo 400mA Vo gt 4 5V Dropout Voltage lo 150mA lo 400mA Quiescent Current lo Vo 1 2V lt Vj 26V
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ST L4920/L4921 handbook