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FEATURES
* 5V, 3.3V, and 3V Versions at 100mA Output Current * High Accuracy Output Voltage * Extremely Low Quiescent Current * Low Dropout Voltage * Extremely Tight Load and Line Regulation * Very Low Temperature Coefficient * Current and Thermal Limiting * Needs Minimum Capacitance (1F) for Stability * Unregulated DC Positive Transients 60V
LP2950/LP2951
100mA LOW DROPOUT VOLTAGE REGULATOR
RoHS compliant
APPLICATIONS
* Battery Powered Systems * Portable Consumer Equipment * Cordless Telephones * Portable (Notebook) Computers * Portable Instrumentation * Radio Control Systems * Automotive Electronics * Avionics * Low-Power Voltage Reference
ADDITIONAL FEATURES (LP2951 ONLY)
* 1.24V to 29V Programmable Output * Error Flag Warning of Voltage Output Dropout * Logic Controlled Electronic Shutdown
GENERAL DESCRIPTION
The LP2950 and LP2951 are micropower voltage regulators ideally suited for use in battery-powered systems. These devices feature very low quiescent current (typ.75A), and very low dropout voltage (typ.45mV at light loads and 380mV at 100mA) thus prolonging battery life. The quiescent current increases only slightly in dropout. The LP2950/LP2951 has positive transient protection up to 60V and can survive unregulated input transient up to 20V below ground. The LP2950 and LP2951 were designed to include a tight initial tolerance (typ. 0.5%), excellent load and line regulation (typ. 0.05%), and a very low output voltage temperature coefficient, making these devices useful as a low-power voltage reference. The LP2950 is offered in the 3-pin TO-92 package. LP2951 is available in 8-pin plastic SOIC and DIP packages and offers three major additional system features. An error flag output warns of a low output voltage, often due to failing batteries on input. The LP2951 also features the logic-compatible shutdown input which enables the regulator to be switched on and off. The LP2951 device may be pin-strapped for a 5V, 3.3V, or 3V output, or programmed from 1.24V to 29V with an external pair of resistors.
ORDERING INFORMATION
PACKAGE TYPE TO-92 8 LEAD PDIP 8 LEAD SOIC LP2950ACN-X LP2951ACP-X LP2951ACS-X LP2950CN-X LP2951CP-X LP2951CS-X X = 3.3V, or 3V OPERATING TEMP. RANGE IND. IND
PIN CONNECTION
8L SOIC/ 8L PDIP
OUTPUT 1 SENSE 2 SHUTDOWN 3 GROUND 4 8 INPUT 7 FEEDBACK 6 VTAP 5 ERROR
Top View TO-92
OUTPUT INPUT
GND
Bottom View
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LP2950/LP2951
ABSOLUTE MAXIMUM RATINGS (Note 1)
Input Supply Voltage SHUTDOWN Input Voltage, Error Comparator Output Voltage,(Note 9) FEEDBACK Input Voltage (Note 9) (Note 10) Power Dissipation Junction Temperature Storage Temperature Soldering Temperature (25 sec) -0.3 to +30V
OPERATING RATINGS
(Note 1) Max. Input Supply Voltage Junction Temperature Range (TJ) (Note 8) LP2950AC-XX, LP2950C-XX LP2951AC-XX, LP2951C-XX 30V
-1.5 to +30V Internally Limited +150C -65C to +150C 260C
-40C to +125C
ELECTRICAL CHARACTERISTICS at Vs=Vout+1V, Ta=25C, unless otherwise noted.
Parameter
3 V Versions (Note 16) Output Voltage TJ = 25C (Note 3) -25C TJ 85C Full Operating Temperature Range 100 A IL 100 mA TJ TJMAX TJ = 25C (Note 3) -25C TJ 85C Full Operating Temperature Range 100 A IL 100 mA TJ TJMAX TJ = 25C (Note 3) -25C TJ 85C Full Operating Temperature Range 100 A IL 100 mA TJ TJMAX 2.985 2.970 2.964 2.958 3.0 3.0 3.0 3.0 3.015 3.030 3.036 3.042 2.970 2.955 2.940 2.928 3.0 3.0 3.0 3.0 3.030 3.045 3.060 3.072 V V V V
Conditions
(Note 2) Min.
LP2950AC LP2951AC
Typ. Max. Min.
LP2950C LP2951C
Typ. Max.
Units
Output Voltage 3.3 V Versions (Note 16) Output Voltage
3.284 3.267 3.260 3.254
3.3 3.3 3.3 3.3
3.317 3.333 3.340 3.346
3.267 3.251 3.234 3.221
3.3 3.3 3.3 3.3
3.333 3.350 3.366 3.379
V V V V
Output Voltage 5 V Versions (Note 16) Output Voltage
4.975 4.95 4.94 4.925
5.0 5.0 5.0 5.0
5.025 5.050 5.06 5.075
4.95 4.925 4.90 4.88
5.0 5.0 5.0 5.0
5.05 5.075 5.10 5.12
V V V V
Output Voltage All Voltage Options Output Voltage Temperature Coefficient Line Regulation (Note 14) Load Regulation (Note 14) Dropout Voltage (Note 5) Ground Current
(Note 12) (Note 4) 6V Vin 30V (Note 15) 100 A IL 100 mA IL = 100 A IL = 100 mA IL = 100 A IL = 100 mA Vout = 0 (Note 13)
20 0.03 0.04 50 380 75 8 160 0.05 0.1 0.1 80 450 120 12 200 0.2
50 0.04 0.1 50 380 75 8 160 0.05 0.2 0.2 80 450 120 12 200 0.2
ppm/C % % mV mV A mA mA %/W
Current Limit Thermal Regulation
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LP2950/LP2951
ELECTRICAL CHARACTERISTICS (Note 2) (Continued)
PARAMETER
Output Noise, 10Hz to 100KHz
CONDITIONS
(Note 2)
CL = 1F CL = 200 F CL = 13.3 F (Bypass = 0.01 F pins 7 to 1(LP2951)) Min.
LP2950AC LP2951AC
Typ. 430 160 100 LP2951AC 1.22 1.235 1.25 1.27 40 20 60 1.21 1.185 Max. Min.
LP2950C LP2951C
Typ. 430 160 100 LP2951C 1.235 1.26 1.285 40 60 50 Max.
Units
V rms V rms V rms
8-Pin Versions only Reference Voltage Reference Voltage Feedback Pin Bias Current Reference Voltage Temperature Coefficient Feedback Pin Bias Current Temperature Coefficient Error Comparator Output Leakage Current Output Low Voltage Upper Threshold Voltage Lower Threshold Voltage Hysteresis Shutdown Input Input logic Voltage Shutdown Pin Input Current (Note 3) Regulator Output Current in Shutdown (Note 3) V
OH
V V nA ppm/C
Over Temperature (Note 7)
1.19
( Note 12 ) 0.1 0.1 nA/C
= 30V
0.01 150 40 60 75 15
1 250 40 95
0.01 150 60 75 15
1 250
A mV mV
Vin = 4.5V IOL = 400A (Note 6) (Note 6) (Note 6) Low (Regulator ON) High (Regulator OFF) Vs = 2.4V Vs = 30V (Note 11)
95
mV mV
1.3 2 30 450 3
0.7 2 50 600 10
1.3 30 450 3
0.7 50 600 10
V V A A A
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, see the Electrical Characteristics tables. Note 2: Unless otherwise specified all limits guaranteed for VIN = ( VONOM +1)V, IL = 100 A and CL = 1 F for 5V versions and 2.2F for 3V and 3.3V versions. Limits appearing in boldface type apply over the entire junction temperature range for operation. Limits appearing in normal type apply for TA = TJ = 25C Additional conditions for the 8-pin versions are FEEDBACK tied to VTAP, OUTPUT tied to SENSE and VSHUTDOWN 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 VIN = ( VONOM +1)V. 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/1.235 = 384 mV. Thresholds remain constant as a percent of Vout as Vout is varied, with the dropout warning occurring at typically 5% below nominal, 7.5% guaranteed. Note 7: Vref Vout (Vin - 1V), 2.3 Vin30V, 100AIL 100 mA, TJ TJMAX. Note 8: The junction-to-ambient thermal resistance are as follows:180C/W and 160C/W for the TO-92 (N) package with 0.40 inch and 0.25 inch leads to the printed circuit board (PCB) respectively, 105C/W for the molded plastic DIP (P) and 160C/W for the molded plastic SO-8 (S). The above thermal resistances for the N, S and P packages apply when the package is soldered directly to the PCB. 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 5VTAP. Note 12: Output or reference voltage temperature coefficients defined as the worst case voltage change divided by the total temperature range.
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LP2950/LP2951
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 regulation effects. Specifications are for a 50mA load pulse at VIN =30V (1.25W pulse) for T =10 ms. 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 are covered under the specification for thermal regulation. Note 15: Line regulation for the LP2951 is tested at 150C for IL = 1 mA. For IL = 100 A and TJ = 125C, line regulation is guaranteed by design to 0.2%. See typical performance characteristics for line regulation versus temperature and load current. Note 16: All LP2950 devices have the nominal output voltage coded as the last two digits of the part number. In the LP2951 products, the 3.0V and 3.3V versions are designated by the last two digits, but the 5V version is denoted with no code of the part number.
BLOCK DIAGRAM AND TYPICAL APPLICATIONS
LP2950-XX LP2951-XX
VOUT IL 100mA 8 INPUT 1 OUTPUT 2 + FROM CMOS OR TTL 3 SHUTDOWN + 50mV + ERROR 4 GROUND ERROR AMPLIFIER SENSE 6 VTAP 5 TO CMOS OR TTL + 330k SEE APPLICATION HINTS
UNREGULATED DC +
+
UNREGULATED DC 7 FEEDBACK
INPUT OUTPUT + ERROR AMPLIFIER + SEE APPLICATION HINTS VOUT IL 100mA
+
1.23V REFERENCE
+
1.23V REFERENCE
GROUND
ERROR DETECTION COMPARATOR
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LP2950/LP2951
TYPICAL PERFORMANCE CHARACTERISTICS
Quiescent Current 10 GROUND CURRENT (mA) OUTPUT VOLTAGE (V) 6
Dropout Characteristics
5V OUTPUT
Input Current 250 225 INPUT CURRENT ( A) 200 175 150 125 100 75 50 25 0
RL= 5V OUTPUT RL= 50 k
5 4 3
RL= 50 RL= 50 k
1
0.1
2 1 0
0.01 0.1
1 10 LOAD CURRENT (mA)
100
0
1
2 3 4 5 INPUT VOLTAGE (V)
6
0
1
2345678 INPUT VOLTAGE (V)
9 10
Input Current 120 110 100 90 80 70 60 50 40 30 20 10 0 5.06
5V OUTPUT RL= 50
Temperature Drift of 3 Representative Units 160
5V OUTPUT
Quiescent Current 140 120 100 80
IL= 0 IL= 1 mA 5V OUTPUT
OUTPUT VOLTAGE (V)
INPUT CURRENT (mA)
5.04 5.02 5.0 4.98 4.96
0.2%
QUIESCENT CURRENT ( A)
60 40 20 0 0 1 23 45 6 INPUT VOLTAGE (V) 7 8
0
1
2345678 INPUT VOLTAGE (V)
9 10
4.94 -75 -50 -25 0 25 50 75 100 125 150 TEMPERATURE ( C)
Quiescent Current 120 QUIESCENT CURRENT ( A)
5V OUTPUT
Quiescent Current 10 QUIESCENT CURRENT (mA)
VIN= 6V
Quiescent Current 8 QUIESCENT CURRENT ( A)
5V OUTPUT
110 100 90 80 70 60
IL= 100A
5V OUTPUT
7 6 5 4 3 2 1 0 0 1 234 5 6 INPUT VOLTAGE (V) 7 8
IL= 100mA
9
VIN= 6V IL= 100mA
8
50 -75 -50 -25 0 25 50 75 100 125 150 TEMPERATURE ( C)
7 -75 -50 -25 0 25 50 75 100 125 150 TEMPERATURE ( C)
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LP2950/LP2951
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
Short Circuit Current 170 SHORT CIRCUIT CURRENT ( mA) DROPOUT VOLTAGE (mV) 160 150 140 130 120 110 100 -75 -50 -25 0 25 50 75 100 125 150 TEMPERATURE ( C) 600 500 400 300
Dropout Voltage 500 DROPOUT VOLTAGE (mV) 400 300 200
Dropout Voltage
IL= 100mA
~ ~
100 50
IL= 100A
TJ = 25C
100 0 100A
0 -75 -50 -25 0 25 50 75 100 125 150 TEMPERATURE ( C)
1mA 10mA OUTPUT CURRENT
100mA
LP2951 Minimum Operating Voltage MINIMUM OPERATING VOLTAGE (V) 2.2 2.1 2.0 1.9 1.8 1.7 1.6 -75 -50 -25 0 25 50 75 100 125 150 TEMPERATURE ( C) BIAS CURRENT (nA) 20
LP2951 Feedback Bias Current 50 FEEDBACK CURRENT (A) 0 -50
LP2951 Feedback Pin Current
PIN 7 DRVEN BY EXTERNAL SOURCE (REGULATOR RUN OPEN LOOP)
10 0 -10
TA = 125C
-100 -150
TA = 25C
-20 -30 -75 -50 -25 0 25 50 75 100 125 150 TEMPERATURE ( C)
-200
TA = -55C
-250 -2.0
0 0.5 -1.5 -1.0 -0.5 FEEDBACK VOLTAGE (V)
1.0
LP2951 Error Comparator Output 9 8 ERROR OUTPUT (V) 7 6 5 4 3 2 1 0 0 1 234567 INPUT VOLTAGE (V) 8
50k RESISTOR TO VOUT HYSTERESIS 50k RESISTOR TO EXTERNAL 5V SUPPLY VOUT= 5V
LP2951 Comparator Sink Current 2.5 2.0 1.5
TA = 25C TA = 125C
INPUT OUTPUT VOLTAGE VOLTAGE CHANGE
SINK CURRENT (mA)
100 mV 50 mV 0 -50 mV 8V 6V 4V
Line Transient Response
CL= 1F IL= 1mA
1.0
TA = -55C
~ ~
VOUT= 5V
0.5 0.0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 OUTPUT LOW VOLTAGE (V)
0
200 400 TIME (s)
600
800
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LP2950/LP2951
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
Load Transient Response 250 200 150 100 50 0 -50 -100 80 60 40 20 0 -20 -40 -60 OUTPUT VOLTAGE CHANGE (mV) OUTPUT VOLTAGE CHANGE (mV)
Load Transient Response OUTPUT VOLTAGE (V) 7 6 5 4 3 2 1 0 2
LP2951 Enable Transient
CL= 1 F
CL= 10 F VOUT = 5V
CL= 10 F
IL= 10 mA VIN = 8V VOUT = 5V
LOAD CURRENT
LOAD CURRENT
~ ~
100 mA 100 A 0 1 2 3 TIME (ms)
~ ~
100 mA 100 A 0 4 8 12 TIME (ms) 16 20
SHUTDOWN PIN VOLTAGE (V) RIPPLE REJECTION (dB)
CL= 1 F VOUT = 5V
~ ~
4
5
0 -2 -100 0 100 200 300 400 500 600 700 TIME (s)
Output Impedance 10 5 OUPUT IMPEDANCE () 2 1 0.5 0.2 0.1 0.05 0.02 0.01 10 100 1K 10K 100K FREQUENCY (Hz) 1M
VOUT = 5V CL= 1 F IO= 100mA IO= 1 mA
Ripple Rejection 90 90 80 70 60 50 40 30
Ripple Rejection
IO= 100A
RIPPLE REJECTION (dB)
80 70 60 50 40 30 20 10 1
CL= 1 F VIN= 6V VOUT = 5V IL= 100A IL= 0
IL= 1mA
CL= 1 F VIN= 6V VOUT = 5V
IL= 10mA
10 2
10 5 10 3 10 4 FREQUENCY (Hz)
10 6
20 10 1
10 2
10 5 10 3 10 4 FREQUENCY (Hz)
10 6
Ripple Rejection 80 RIPPLE REJECTION (dB) 70 60 50 40 30 20 10 10 1 10 2 10 5 10 3 10 4 FREQUENCY (Hz) 10 6
CL= 1F VIN= 6V VOUT= 5V
LP2951 Output Noise 3.5 VOLTAGE NOISE SPECTRAL DENSITY(mV/Hz) 400
5V OUTPUT IL= 100mA
LP2951 Divider Resistance PIN 2 TO PIN 4 RESISTANCE (k ) 10 5
IL= 50mA
3.0 2.5 2.0 1.5 1.0 0.5 0.0
0.01 F BYPASS PIN 1 TO PIN 7 CL= 3.3 F CL= 220 F CL= 1 F
IL= 100mA
300
200
100
10 2
10 3 10 4 FREQUENCY (Hz)
0 -75 -50 -25 0 25 50 75 100 125 150 TEMPERATURE ( C)
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LP2950/LP2951
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
Shutdown Treshold Voltage SHUTDOWN TRESHOLD VOLTAGE (V) 1.8 OUTPUT VOLTAGE CHANGE (V) 1.6 1.4 1.2 1.0 0.8 0.6 -75 -50 -25 0 25 50 75 100 125 150 TEMPERATURE ( C)
REGULATOR ON REGULATOR OFF
Line Regulation 30 25 20 15 10 5 0 120 OUTPUT CURRENT ( mA)
IL= 100A TJ = 150 C IL= 1mA
LP2951 Maximum Rated Output Current
8 PIN MOLDED DIP SOLDERED TO PC BOARD TJMAX= 125 C VOUT = 5V TA= 25 C TA= 50 C
100 80 60 40 20 0
~ ~
10 5 0 -5 -10
TJ = 125 C IL= 100A
TA= 85 C
5
15 20 25 10 INPUT VOLTAGE (V)
30
0
10 5 15 20 INPUT VOLTAGE (V)
25
30
LP2950 Maximum Rated Output Current 120 OUTPUT CURRENT ( mA) 100 80 60
TA= 25 C TO-92 PACKAGE .25"LEADS SOLDERED TO PC BOARD TJMAX= 125 C
Thermal Response POWER OUTPUT VOLTAGE DISSIPATION (W) CHANGE (mV) 5 4 2 0 -2 1 0 -1 0 10 20 30 TIME (s) 40 50
40 20 0 0 10 5 15 20 INPUT VOLTAGE (V) 25 30
TA= 85 C
~ ~
1.25W
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APPLICATION HINTS
External Capacitors A 1.0 F or greater capacitor is required between output and ground for stability at output voltages of 5V or more. At lower output voltages, more capacitance is required (2.2 or more is recommended for 3V and 3.3V versions). Without this capacitor the part will oscillate. Most types of tantalum or aluminum electrolytic works fine here; even film types work but are not recommended for reasons of cost. Many aluminum types have electrolytes that freeze at about -30C, so solid tantalums are recommended for operation below -25C. The important parameters of the capacitor are an ESR of about 5 or less and resonant frequency above 500 kHz parameters in the value of the capacitor. 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 F for currents below 10 mA or 0.1 F for currents below 1 mA. Using the adjustable versions 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 100mA load at 1.23V output (Output shorted to Feedback) a 3.3F (or greater) capacitor should be used. Unlike many other regulators, the LP2950, 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 voltage of the LP2951 version with external resistors, a minimum load of 1A is recommended. A 1F tantalum or aluminum electrolytic capacitor should be placed from the LP2950/LP2951 input to the 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 LP2951 Feedback terminal can cause instability. This may especially be a problem when using a higher value of external resistors to set the output voltage. Adding a 100 pF capacitor between Output and Feedback and increasing the output capacitor to at least 3.3 F will fix this problem. Error Detection Comparator Output The comparator produces a logic low output whenever the LP2951 output falls out of regulation by more than approximately 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 programmed output voltage of the 2951. 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 limiting. Figure 1 gives a timing diagram depicting the ERROR signal and the regulator output voltage as the LP2951 input is ramped up and down. For 5V versions the ERROR signal becomes valid (low) at about 1.3V input. It goes high at about 5V input (the input voltage at which Vout = 4.75 ). Since the LP2951'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 depending on system requirements. In determining a value for this resistor, note that the output is rated to sink 400A, this sink current adds to battery drain in a low battery condition. Suggested values range from 100K to 1M. The resistor is not required if this output is unused. Programming the Output Voltage (LP2951) The LP2951 may be pin-strapped for the nominal fixed output voltage using its internal voltage divider by tying the output and sense pins together, and also tying the feedback and VTAP pins together. Alternatively, it may be programmed for any output voltage between its 1.235V reference and its 30V maximum rating. As seen in Figure 2, an external pair of resistors is required. The complete equation for the output voltage is: Vout = VREF x (1 + R1/ R2)+ IFBR1 where VREF is the nominal 1.235 reference voltage and IFB is the feedback pin bias current, nominally -20 nA. The minimum recommended load current of 1 A forces an upper limit of 1.2 M on value of R2, if the regulator must work with no load (a condition often found in CMOS in standby) IFB will produce a 2% typical error in VOUT which may be eliminated at room temperature by trimming R1. For better accuracy, choosing R2 = 100k reduces this error to 0.17% while increasing the resistor program current by 12 A. Since the LP2951 typically draws 60 A at no load with Pin 2 open-circuited, this is a small price to pay. Reducing Output Noise In reference applications it may be an advantageous to reduce the AC noise present at the output. One method is to reduce the regulator bandwidth by increasing the size of the output capacitor. This is the only way that noise can be reduced on the 3 lead LP2950 but is relatively inefficient, as increasing the capacitor from 1 F to 220 F only decreases the noise from 430 V to 160 V rms for a 100 kHz bandwidth at 5V output. Noise could also be reduced fourfold by a bypass capacitor across R1, since it reduces the high frequency gain from 4 to unity. Pick CBYPASS 1 / 2R1 x 200 Hz or about 0.01 F. When doing this, the output capacitor must be increased to 3.3 F to maintain stability. These changes reduce the output noise from 430 V to 100 V rms for a 100 kHz bandwidth at 5V output. With the bypass capacitor added, noise no longer scales with output voltage so that improvements are more dramatic at higher output voltages.
LP2950/LP2951
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APPLICATION HINTS (Continued)
+VIN
OUTPUT VOLTAGE
4.75V
100k
8 +VIN 5 ERROR* 3 1 VOUT 1.2 30V
ERROR*
ERROR OUPUT **SHUTDOWN INPUT
VOUT
LP2951 SD GND 4 FB 7 R1
INPUT VOLTAGE 1.3V
5V
*+ .01 F
3.3F
1.23V
VREF
R2
FIGURE 1. ERROR Output Timing
*When VIN 1.3V the error flag pin becomes a high impedance, and the error flag voltage rises to its pull-up voltage. Using Vout as the pull-up voltage (see Figure 2), rather than an external 5V source, will keep the error flag voltage under 1.2V (typ.) in this condition. The user may wish to drive down the error flag voltage using equal value resistors (10 k suggested), to ensure a low-level logic signal during any fault condition, while still allowing a valid high logic level during normal operation.
FIGURE 2. Adjustable Regulator
*See Application Hints. Vout = VREF x (1 + R1/ R2) **Drive with TTL- high to shut down. Ground or leave if shutdown feature is not used. Note: Pins 2 and 6 are left open.
TYPICAL APPLICATIONS
300 mA Regulator with 0.75 Dropout
UNREGULATED INPUT 8 IN LP2951 6 VTAP FB 7 SENSE GND 4 2 4.7F OUT 1 330 2N5432 (2) 27k 5V OUTPUT LOAD 50mA TO 300mA
Wide Input Voltage Range Current Limiter
+VIN 8 +VIN ERROR OUPUT 5 ERROR LP2951 SHUTDOWN 3 SD INPUT GND 4 FB 7 VOUT 1 *VOUT V
*Minimum Input-Output voltage ranges from 40mV to 400mV, depending on load current. Current limit is typically 160 mA
LP2950/LP2951
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TYPICAL APPLICATIONS (Continued)
Low Drift Current Source
+V = 2 IL 30V
5Volt Current Limiter
LOAD
5V BUS
8 VIN VOUT LP2951 SHUTDOWN 3 SD INPUT GND 4 R 1% FB 7 + 0.1F 1
+VIN LP2950 -5.0 VOUT 1F GND *VOUT 5V
1F
*Minimum Input-Output voltage ranges from 40mV to 400mV, depending on load current. Current limit is typically 160 mA
5V Regulator with 2.5V Sleep Function
+VIN *SLEEP INPUT 47k 8 +VIN ERROR OUPUT 5 ERROR VOUT 1 +VOUT C - MOS GATE
Open Circuit Detector for 4 to 20mA Current Loop
+5V 4.7k 4 20mA 1 8 *OUTPUT 5
470k
+VIN VOUT LP2951 1N4001 7 FB GND 4 1N457 360 2 1 4
SHUTDOWN 3 SD INPUT GND 4
LP2951 100pF FB 7 2N3906
200k 1% + 3.3F
0.1F
100k 1% 100k
MIN. VOLTAGE 4V
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LP2950/LP2951
TYPICAL APPLICATIONS (Continued)
2 Ampere Low Dropout Regulator
CURRENT LIMIT SECTION
Regulator with Early Warning and Auxiliary Output
+VIN 8 +VIN 6 VTAP 2 SENSE VOUT 1 D2 5V MEMORY SUPPLY
+VIN = VOUT +.5V
D1
680
0.05
470
7
2N3906 4.7M 8 +VIN ERROR LP2951 3 SD GND 4 20k .033 FB VOUT 1 5 ERROR FLAG 7 R1 1% R2 + + 10k MJE2955 +VOUT @ 2A
LP2951 #1 5 ERROR FB GND 4
+ 1F
20 3.6V NICAD
27 k 4.7 TANT.
100F
2.7M D4 Q1 6 7 3
D3
EARLY WARNING
220
8 +VIN VTAP FB SD
2 SENSE VOUT
330 k MAIN 5V OUTPUT
RESET P VDD
LP2951 #2 5 ERROR GND 4
+
1F
VOUT = 1.23V(1+R1/R2) For 5V VOUT, use internal resistors. Wire pin 6 to 7 and pin 2 to +VOUTBuss.
* Early warning flag on low input voltage * Main output latches off at lower input voltages * Battery backup on auxiliary output Operation: Reg.#1's VOUT is programmed one diode drop above 5V. It's error flag becomes active when VIN 5.7V. When VIN drops below 5.3V, the error flag of Reg.#2 becomes active and via Q1 latches the main output off. When VIN again exceeds 5.7V Reg.#1 is back in regulation and the early warning signal rises, unlatching Reg.#2 via D3.
1A Regulator with 1.2V Dropout
UNREGULATED INPUT 1F 10k 0.01F SUPERTEX VP12C 8 IN 6 VTAP SENSE LP2951 7 FB GND 4 OUT 1 0.002F 2k IQ 400A 2 + 220F OUTPUT 5V 1% @ 0 TO 1A
Latch Off When Error Flag Occurs
+VIN
470k 5 470k
8 +VIN 1 VOUT ERROR LP2951 3 SD FB GND 4 7 R1 + 1F VOUT
RESET
R2
1
Advanced Monolithic Systems, Inc.
www.advanced-monolithic.com
Phone (925) 443-0722
Fax (925) 443-0723
LP2950/LP2951
PACKAGE DIMENSIONS inches (millimeters) unless otherwise noted.
3 LEAD TO-92 PLASTIC PACKAGE (N)
0.0600.005 (1.5240.127) DIA
0.1800.005 (4.5720.127) 0.0600.010 (1.5240.254) 0.1400.010 (3.5560.127)
0.1800.005 (4.5720.127)
0.90 (2.286) NOM
5 NOM 0.500 (12.70) MIN
10 NOM
0.050 (1.270) MAX
UNCONTROLLED LEAD DIMENSIONS
0.0500.005 (1.2700.127)
0.0160.003 (0.4060.076)
0.0150.002 (0.3810.051)
N (TO-92 ) AMS DRW# 042391
8 LEAD SOIC PLASTIC PACKAGE (S)
0.189-0.197* (4.801-5.004) 8 7 6 5
0.228-0.244 (5.791-6.197)
0.150-0.157** (3.810-3.988)
1
2
3
4
0.053-0.069 (1.346-1.752) 0.004-0.010 (0.101-0.254) 0.008-0.010 (0.203-0.254)
0.010-0.020 x 45 (0.254-0.508) 0-8 TYP
0.014-0.019 (0.355-0.483)
0.050 (1.270) TYP
0.016-0.050 (0.406-1.270)
S (SO-8 ) AMS DRW# 042293
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
Advanced Monolithic Systems, Inc.
www.advanced-monolithic.com
Phone (925) 443-0722
Fax (925) 443-0723
LP2950/LP2951
PACKAGE DIMENSIONS inches (millimeters) unless otherwise noted (Continued).
8 LEAD PLASTIC DIP PACKAGE (P)
0.400* (10.160) MAX 8 7 6 5
0.2550.015* (6.4770.381)
1
2
3
4
0.045-0.065 (1.143-1.651)
0.1300.005 (3.3020.127)
0.300-0.325 (7.620-8.255)
0.065 (1.651) TYP 0.005 (0.127) MIN 0.1000.010 (2.5400.254) 0.125 (3.175) MIN 0.0180.003 (0.4570.076) 0.015 (0.380) MIN
0.009-0.015 (0.229-0.381) 0.325 +0.025 -0.015
(8.255 +0.635 )
-0.381
P (8L PDIP ) AMS DRW# 042294
*DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTUSIONS. MOLD FLASH OR PROTUSIONS SHALL NOT EXCEED 0.010" (0.254mm)
Advanced Monolithic Systems, Inc.
www.advanced-monolithic.com
Phone (925) 443-0722
Fax (925) 443-0723

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