LP4950C-5V

LP4950C-5V NSC | Alldatasheet

Document overview

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Technical content

Features

n High accuracy 5V guaranteed 100mA output n Extremely low quiescent current n Low dropout voltage n Extremely tight load and line regulation n Very low temperature coefficient n Use as Regulator or Reference n Needs only 1µF for stability n Current and Thermal Limiting LP4951C versions only n Error flag warns of output dropout n Logic-controlled electronic shutdown n Output programmable from 1.24 to 29V Block Diagram and Typical

Applications

LP4950C-5V and LP4951C Adjustable Micropower Voltage Regulators © 2002 National Semiconductor Corporation DS200528 www.national.com

Absolute Maximum Ratings(Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Input Supply Voltage −0.3 to +30V SHUTDOWN Input Voltage, Error Comparator Output Voltage, (Note 9) −0.3 to +30V FEEDBACK Input Voltage −1.5 to +30V (Note 9) (Note 10) Power Dissipation Internally Limited Junction Temperature (T J) +150˚C Ambient Storage Temperature −65˚ to +150˚C Soldering Dwell Time, Temperature Wave Infrared Vapor Phase 4 seconds, 260˚C 10 seconds, 240˚C 75 seconds, 219˚C ESD TBD Operating Ratings(Note 1) Maximum Input Supply Voltage 30V Junction Temperature Range (Note 8) LP4950C, LP4951C −40˚C to 125˚C Electrical Characteristics(Note 2) Parameter Conditions (Note 2) LP4950CZ Units LP4951CM Tested Design Typ Limit Limit (Note 3) (Note 4) Output Voltage T J = 25˚C 5.0 5.1 V max

4.9 V min

−25˚C ≤ TJ ≤ 85˚C 5.15 V max

4.85 V min

Full Operating 5.2 V max Temperature Range 4.8 V min Output Voltage 100 µA ≤ IL ≤ 100 mA 5.24 V max TJ ≤ TJMAX 4.76 V min Output Voltage Temperature Coefficient (Note 12) 150 ppm/˚C Line Regulation (Note 14) 6V ≤ VIN ≤ 30V (Note 15) 0.04 0.2 % max 0.4 % max Load Regulation (Note 14) 100µA ≤ IL ≤ 100mA 0.1 0.2 % max 0.3 % max Dropout Voltage (Note 5) IL = 100µA 50 80 mV max 150 mV max IL = 100mA 380 450 mV max 600 mV max Ground Current I L = 100µA 75 150 µA max 170 µA max IL = 100mA 8 15 mA max 19 mA max Dropout Ground Current V IN = 4.5V 110 200 µA max IL = 100µA 230 µA max Current Limit V OUT = 0 160 200 mA max 220 mA max Thermal Regulation (Note 13) 0.05 0.2 %/W max Output Noise, C L = 1µF 430 µV rms

10 Hz to 100 kHz C L = 200µF 160 µV rms

CL = 3.3µF (Bypass = 0.01µF Pins 7 to 1 (LP4951C) 100 µV rms LP4950C-5V and LP4951C www.national.com 2

Electrical Characteristics

Parameter Conditions (Note 2) Typ Tested Limit (Note Desgin Limit (Note Units 8-PIN VERSIONS ONLY Reference Voltage 1.235 1.285 V max

1.295 V max

1.185 V min

1.165 Vmin

Reference Voltage (Note 7) 1.335 V max

1.135 V min

(Note 12) 50 ppm/˚C Feedback Pin Bias Current Temperature Coefficient 0.1 nA/˚C Error Comparator Output Leakage Current V OH = 30V 0.01 1 µA max 2 µA max Output Low Voltage V IN = 4.5V IOL = 400µA 150 250 mV max 400 mV max Upper Threshold Voltage (Note 4) 60 40 mV min 25 mV min Lower Threshold Voltage (Note 6) 75 95 mV max 140 mV max Hysteresis (Note 6) 15 mV Shutdown Input Input Logic Voltage 1.3 V Low (Regulator ON) 0.7 V max High (Regulator OFF) 2.0 V min Shutdown Pin Input Current V SHUTDOWN = 2.4V 30 50 µA max 100 µA max VSHUTDOWN = 30V 450 600 µA max 750 µA max Regulator Output Current in Shutdown (Note 11) 3 10 µA max 20 µA max Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, se e the Electrical Characteristics tables. Note 2: Unless otherwise specified all limits guaranteed for V IN =6 V ,IL = 100µA and C L = 1µF. Limits appearing in boldface type apply over the entire junction temperature range for operation. Limits appearing in normal type apply for TA =T J = 25˚C. Additional conditions for the 8-pin versions are FEEDBACK tied to VTAP, OUTPUT tied to SENSE (V OUT = 5V), and V SHUTDOWN ≤ 0.8V. Note 3: Guaranteed and 100% production tested. Note 4: Guaranteed but not 100% production tested. These limits are not used to calculate outgoing AQL levels. Note 5: Dropout Voltage is defined as the input to output differential at which the output voltage drops 100 mV below its nominal value measured at 1V differential. At very low values of programmed output voltage, the minimum input supply voltage of 2V (2.3V over temperature) must be taken into account. Note 6: Comparator thresholds are expressed in terms of a voltage differential at the Feedback terminal below the nominal reference voltage measured at V IN = 6V. To express these thresholds in terms of output voltage change, multiply by the error amplifier gain = VOUT/VREF = (R1 + R2)/R2.For example, at a programmed output voltage of 5V, the Error output is guaranteed to go low when the output drops by 95 mV x 5V/1.235V = 384 mV.Thresholds remain constant as a percent o f VOUT as VOUT is varied, with the dropout warning occurring at typically 5% below nominal, 7.5% guaranteed. Note 7: VREF ≤ VOUT ≤ (VIN − 1V), 2.3V ≤ VIN ≤ 30V, 100µA ≤ IL ≤ 100mA, TJ ≤ TJMAX. Note 8: The junction-to-ambient thermal resistances are as follows: 180˚C/W and 160˚C/W for the TO-92 package with 0.40 inch and 0.25 inch leads to the printed circuit board (PCB) respectively, 160˚C/W for the molded plastic SOP (M). The above thermal resistances for the M package apply when the package is sol dered directly to the PCB. LP4950C-5V and LP4951C www.national.com3

Electrical Characteristics (Continued) Note 9: May exceed input supply voltage. Note 10: When used in dual-supply systems where the output terminal sees loads returned to a negative supply, the output voltage should be diode-clamped to ground. Note 11: VSHUTDOWN ≥ 2V, VIN ≤ 30V, VOUT = 0, Feedback pin tied to V TAP. Note 12: Output or reference voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range. Note 13: Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding load or line regulati on effects. Specifications are for a 50 mA load pulse at V IN = 30V (1.25W pulse) for T = 10ms. Note 14: Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects a re covered under the specification for thermal regulation. Note 15: Line regulation for the LP4951C is tested at 150˚C for I L = 1 mA. For I L = 100µA and TJ = 125˚C, line regulation is guaranteed by design to 0.2%. See Typical Performance Characteristics for line regulation versus temperature and load current. Connection Diagrams TO-92 Plastic Package (Z) Surface-Mount Package (M) 20052802 Bottom View 20052826 Top View

Ordering Information

Package Output Voltage Temperature 5.0V TO-92 (Z) LP4950CZ-5.0 −40˚C < TJ < 125˚C M (M08A) LP4951CM −40˚C < TJ < 125˚C LP4950C-5V and LP4951C www.national.com 4

Typical Performance Characteristics Quiescent Current Dropout Characteristics 20052827 20052828 Input Current Input Current 20052829 20052830 Output Voltage vs. Temperature of 3 Representative Units Quiescent Current 20052831 20052832 LP4950C-5V and LP4951C www.national.com5

Typical Performance Characteristics (Continued) Quiescent Current Quiescent Current 20052833 20052834 Quiescent Current Short Circuit Current 20052835 20052836 Dropout Voltage Dropout Voltage 20052837 20052838 LP4950C-5V and LP4951C www.national.com 6

Typical Performance Characteristics (Continued) LP4951C Minimum Operating Voltage LP4951C Feedback Bias Current 20052839 20052840 LP4951C Feedback Pin Current LP4951C Error Comparator Output 20052841 20052842 LP4951C Comparator Sink Current Line Transient Response 20052843 20052844 LP4950C-5V and LP4951C www.national.com7

Typical Performance Characteristics (Continued) Load Transient Response Load Transient Response 20052845 20052846 LP4951C Enable Transient Output Impedance 20052847 20052848 Ripple Rejection Ripple Rejection 20052849 20052850 LP4950C-5V and LP4951C www.national.com 8

Typical Performance Characteristics (Continued) Ripple Rejection Output Noise 20052851 20052852 LP4951C Divider Resistance Shutdown Threshold Voltage 20052853 20052854 Line Regulation LP4951C Maximum Rated Output Current 20052855 20052857 LP4950C-5V and LP4951C www.national.com9

Typical Performance Characteristics (Continued) Thermal Response 20052858 Application Hints EXTERNAL CAPACITORS A 1.0µF (or greater) capacitor is required between the output and ground for stability at output voltages of 5V or more. At lower output voltages, more capacitance is required. Without this capacitor the part will oscillate. Most types of tantalum or aluminum electrolytics work fine here; even film types work but are not recommended for reasons of cost. Many alumi- num electrolytics have electrolytes that freeze at about −30˚C, so solid tantalums are recommended for operation below −25˚C. The important parameters of the capacitor are an ESR of about 5Ω or less and a resonant frequency above 500 kHz. The value of this capacitor may be increased without limit. At lower values of output current, less output capacitance is required for stability. The capacitor can be reduced to 0.33 µF for currents below 10 mA or 0.1 µF for currents below 1 mA. Using the 8-pin version at voltages below 5V runs the error amplifier at lower gains so that more output capacitance is needed. For the worst-case situation of a 100 mA load at 1.23V output (Output shorted to Feedback) a 3.3 µF (or greater) capacitor should be used. Unlike many other regulators, the LP4950C will remain stable and in regulation with no load in addition to the internal voltage divider. This is especially important in CMOS RAM keep-alive applications. When setting the output volt- age of the LP4951C version with external resistors, a mini- mum load of 1µA is recommended. A 0.1µF capacitor should be placed from the LP4950C/ LP4951C input to ground if there is more than 10 inches of wire between the input and the AC filter capacitor or if a battery is used as the input. Stray capacitance to the LP4951C Feedback terminal (pin 7) can cause instability. This may especially be a problem when using high value external resistors to set the output voltage. Adding a 100pF capacitor between Output and Feedback and increasing the output capacitor to at least 3.3µF will fix this problem. ERROR DETECTION COMPARATOR OUTPUT The comparator produces a logic low output whenever the LP4951C output falls out of regulation by more than approxi- mately 5%. This figure is the comparator’s built-in offset of about 60 mV divided by the 1.235 reference voltage. (Refer to the block diagram in the front of the datasheet.) This trip level remains “5% below normal” regardless of the pro- grammed output voltage of the 4951C. For example, the error flag trip level is typically 4.75V for a 5V output or 11.4V for a 12V output. The out of regulation condition may be due either to low input voltage, current limiting, or thermal limit- ing. Figure 1below gives a timing diagram depicting the ERROR signal and the regulated output voltage as the LP4951C input is ramped up and down. The ERROR signal becomes valid (low) at about 1.3V input. It goes high at about 5V input (the input voltage at which V OUT = 4.75V). Since the LP4951C’s dropout voltage is load-dependent (see curve in typical performance characteristics), the input voltage trip point (about 5V) will vary with the load current. The output voltage trip point (approx. 4.75V) does not vary with load. The error comparator has an open-collector output which requires an external pullup resistor. This resistor may be returned to the output or some other supply voltage depend- ing on system requirements. In determining a value for this resistor, note that while the output is rated to sink 400µA, this sink current adds to battery drain in a low battery condition. Suggested values range from 100k to 1 M Ω. The resistor is not required if this output is unused. LP4950C-5V and LP4951C www.national.com 10

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Physical Dimensions inches (millimeters) unless otherwise noted Surface Mount Package (M) Molded TO-92 Package (Z) LP4950C-5V and LP4951C www.national.com13

NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. National Semiconductor Corporation Americas Email: support@nsc.com National Semiconductor Europe Fax: +49 (0) 180-530 85 86 Email: europe.support@nsc.com Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: ap.support@nsc.com National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507 www.national.com LP4950C-5V and LP4951C Adjustable Micropower Voltage Regulators National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the righ t at any time without notice to change said circuitry and specifications.