L4922.pdf part of SGS-Thomson L4922 L4922.pdf, Very low drop regulator with reset text manual preview

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L4922

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VERY LOW DROP REGULATOR WITH RESET
VERY LOW DROP (max. 0.9 V at 1 A) OVER FULL OPERATING TEMPERATURE RANGE ( 40 / + 125°C) LOW QUIESCENT CURRENT (max 70 mA at 1 A) OVER FULL T RANGE PRECISE OUTPUT VOLTAGE (5 V ± 4 %) OVER FULL T RANGE POWER ON-OFF INFORMATION WITH SETTABLE DELAY REVERSE BATTERY PROTECTION SHORT CIRCUIT PROTECTION THERMAL SHUTDOWN

Pentaw att ORDERING NUMBER : L4922

DESCRIPTION The L4922 is a high current monolithic voltage regulator with very low voltage drop (0.70 V max at 1 A, TJ = 25 °C). The device is internally protected against load dumps transient of + 60V, reverse polarity, over-

heatingand output short circuit : thanks toted for the automotive and industrial applications.

BLOCK DIAGRAM

October 1991
This is advanced information on a new product now in development or undergoing evaluation. Details are subject to change without notice.

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L4922
ABSOLUTE MAXIMUM RATINGS
Symbol Vi Vr VD TJ T op Tstg DC Input Voltage DC Reverse Voltage Positive Load Dump Protection (t = 300ms) Junction Temperature Range Operating Temperature Range Storage Temperature Range Parameter Value 35 18 60 40 to 150 40 to 125 55 to 150 Unit V V V °C °C °C

Note: The circuit is ESD protected according to MIL-STD-883C

THERMAL DATA
Symbol Rth j-case Parameter Thermal Resistance Junction-case Max. Value 3.5 Unit °C/W

PIN CONNECTION (Top view)

FUNCTIONAL DESCRIPTION The operating principle of the voltage regulator is based on the reference, the error amplifier, the driver and the power PNP. This stage uses an Isolated Collector Vertical PNP transistor which allows to obtain very low dropout voltage (typ. 450mV) and low quiescentcurrent (IQ = 20mAtypically atIo = 1A). Thanks to these features the device is particularly suited when the power dissipation must be limited as, for example, in automotive or industrial applications supplied by battery. The three gain stages (operational amplifier, driver and power PNP) require the external capacitor (Comin = 22µF) to guarantee the global stability of the system.

The antisaturationcircuit allows to reduce drastically the current peak which takes place during the start up. The reset function is LOW active when the output voltage level is lower than the reset threshold voltage VRthOFF (typ.value : Vo 150mV). When the output voltage is higher than VRthON the reset becomes HIGH after a delay time settablewith the externalcapacitor Cd. Typically td = 20ms, Cd = 0.1µF. The reset and delay threshold hysteresis improve the noise immunity allowing to avoid false switchings. The typical reset output waveform is shown in fig. 1.

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L4922
ELECTRICAL CHARACTERISTICS (Vi = 14. 4V, 40°C TJ + 125°C unless otherwise specified)
Symbol Vi Vo VLine SVR Parameter Operating Input Voltage Output Voltage Line Regulation Supply Voltage Rejection Test Conditions (*) Note 1 Io = 0mA to 1A TJ = 25°C Vi = 6 to 26V; IO = 10mA Io = 700mA f = 120Hz; Co = 47µF Vi = 12Vdc + 5Vpp Io = 10mA to 1A TJ = 25°C, IO = 1A Over Full T, Io = 1A Iq ISC VR VRT peak IR tD VRthOFF Quiescent Current Short Circuit Current Rset Output Saturation Voltage Power On-Off Reset out Peak Voltage Reset Output Leakage Current (high level) Reset Pulse Delay Time Power OFF Vo Threshold 1.5V < VO < VRT (off), IR = 1.6mA 3V < VO < VRT (off), IR = 8mA 1K Reset Pull-up to VO Vo in Regul. VR = 5V CD = 100nF Vo @ Reset out H to L Transition; TJ = 25°C 40°C TJ + 125°C V4 = 3V Vo @ Reset out L to H Transition Reset out = "1" H to L Transition Reset out = "0" L to H Transition V6H Delay Comparator Hysteresis 3.2 3.7 4 500 4.75 4.70 20 Vo 0.15 20 VrthOFF + 0.03V Vo 0.04V 3.8 4.4 0.65 Io = 10mA Io = 1A 7 25 1.8 0.40 0.40 1.0 50 Min. 6 4.8 4.9 5 55 Typ. Max. 26 5.2 5.1 25 Unit V V V mV dB

VLOAD Vi Vo

Load Regulation Dropout Voltage

15 0.45

50 0.70 0.90 12 70

mV V V mA mA A V V V µA ms V V µA V V V mV

IC6 VRthON V4

Delay Capacitor Charging Current (current generator) Power ON Vo Threshold Delay Comparator Threshold

(*) Note 1 : The device is not operating within the range : 26 V < Vi < 37 V.

EXTERNAL COMPENSATION Since the purpose of a voltage regulator is to supply a fixed output voltage in spite of supply and load variations, the open loop gain of the regulator must be very high at low frequencies. This may cause instability as a result of the various poles present in the loop. To avoid this instability dominant pole compensation is used to reduce phase shifts due to other poles at the unity gain frequency. The lower the frequency of these other poles, the greater must be the capacitor used to create the dominant pole for the same DC gain.

Where the output transistor is a lateral PNP type there is a pole in the regulation loop at a frequency too low to be compensated by a capacitor wich can be integrated. An external compensation is therefore necessary so a very high value capacitor must be connected from the output to ground. The parassitic equivalent series resistance of the capacitor used adds a zero to the regulation loop. This zero may compromise the stability of the system since its effect tends to cancel the effect of the pole added. In regulatorsthis ESR must be less than 3 and the minimum capacitor value is 47µF.

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L4922
Figure 1 : Typical Reset Output Waveform.

Figure 2 : Typical Application Circuit.

(*) RECOMMENDED VALUE : C0 = 47 µF, ESR < 10 ohm, (Iout > 10 mA) OVER FULL Trange.

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L4922
PENTAWATT PACKAGE MECHANICAL DATA
DIM. MIN. A C D D1 E F F1 G G1 H2 H3 L L1 L2 L3 L5 L6 L7 M M1 Dia 3.65 2.6 15.1 6 4.5 4 3.85 0.144 10.05 17.85 15.75 21.4 22.5 3 15.8 6.6 0.102 0.594 0.236 0.177 0.157 0.152 2.4 1.2 0.35 0.8 1 3.4 6.8 10.4 10.4 0.396 0.703 0.620 0.843 0.886 0.118 0.622 0.260 mm TYP. MAX. 4.8 1.37 2.8 1.35 0.55 1.05 1.4 0.094 0.047 0.014 0.031 0.039 0.126 0.260 0.134 0.268 MIN. inch TYP. MAX. 0.189 0.054 0.110 0.053 0.022 0.041 0.055 0.142 0.276 0.409 0.409

L E L1

A

C

D1

L2 L5 L3

D

Dia. F

L6

H2

L7

F1

G

G1

H3

M

M1

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L4922

Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics 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 SGS-THOMSON Microelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics. © 1994 SGS-THOMSON Microelectronics - All Rights Reserved SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands - Singapore Spain - Sweden - Switzerland - Taiwan - Thaliand - United Kingdom - U.S.A.

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