ON Semiconductor Three-Terminal Adjustable Output Positive Voltage Regulator The LM350 is an adjustable three–terminal positive voltage regulator capable of supplying in excess of 3.0 A over an output voltage range of 1.2 V to 33 V. This voltage regulator is exceptionally easy to use and requires only two external resistors to set the output voltage. Further, it employs internal current limiting, thermal shutdown and safe area compensation, making it essentially blow–out proof. The LM350 serves a wide variety of applications including local, on card regulation. This device also makes an especially simple adjustable switching regulator, a programmable output regulator, or by connecting a fixed resistor between the adjustment and output, the LM350 can be used as a precision current regulator. • Guaranteed 3.0 A Output Current • Output Adjustable between 1.2 V and 33 V • Load Regulation Typically 0.1% • Line Regulation Typically 0.005%/V • Internal Thermal Overload Protection • Internal Short Circuit Current Limiting Constant with Temperature • Output Transistor Safe Area Compensation • Floating Operation for High Voltage Applications • Standard 3–lead Transistor Package • Eliminates Stocking Many Fixed Voltages LM350 THREE–TERMINAL ADJUSTABLE POSITIVE VOLTAGE REGULATOR SEMICONDUCTOR TECHNICAL DATA T SUFFIX PLASTIC PACKAGE CASE 221A Pin 1. Adjust 2. Vout 3. Vin 1 2 3 Heatsink surface is connected to Pin 2. ORDERING INFORMATION Device Simplified Application LM350T Vin vout LM350 IAdj Cin* 0.1µF LM350BT# Package TJ = 0° to +125°C Plastic Power TJ = –40° to +125°C Plastic Power # Automotive temperature range selections are available with special test conditions and additional tests. Contact your local ON Semiconductor sales office for information. R1 240 Adjust Operating Temperature Range + C ** O 1µF R2 * = Cin is required if regulator is located an appreciable distance from power supply filter. ** = CO is not needed for stability, however, it does improve transient response. R Vout 1.25V 1 2 IAdjR2 R1 Since IAdj is controlled to less than 100 µA, the error associated with this term is negligible in most applications. Semiconductor Components Industries, LLC, 2001 April, 2001 – Rev. 1 1 Publication Order Number: LM350/D LM350 MAXIMUM RATINGS Rating Symbol Value Unit VI–VO 35 Vdc Power Dissipation PD Internally Limited W Operating Junction Temperature Range TJ –40 to +125 °C Storage Temperature Range Tstg –65 to +150 °C Tsolder 300 °C Input–Output Voltage Differential Soldering Lead Temperature (10 seconds) ELECTRICAL CHARACTERISTICS (VI–VO = 5.0 V; IL = 1.5 A; TJ = Tlow to Thigh; Pmax [Note 1], unless otherwise noted.) Figure Symbol Min Typ Max Unit Line Regulation (Note 2) TA = 25°C, 3.0 V ≤ VI–VO ≤ 35 V 1 Regline – 0.0005 0.03 %/V Load Regulation (Note 2) TA = 25°C, 10 mA ≤ Il ≤ 3.0 A VO ≤ 5.0 V VO ≥ 5.0 V 2 Regload – – 5.0 0.1 25 0.5 mV % VO Regtherm – 0.002 – % VO/W 3 IAdj – 50 100 µA Adjustment Pin Current Change 3.0 V ≤ VI–VO ≤ 35 V 10 mA ≤ IL ≤ 3.0 A, PD ≤ Pmax 1,2 ∆IAdj – 0.2 5.0 µA Reference Voltage 3.0 V ≤ VI–VO ≤ 35 V 10 mA ≤ IO ≤ 3.0 A, PD ≤ Pmax 3 Vref 1.20 1.25 1.30 V Line Regulation (Note 2) 3.0 V ≤ VI–VO ≤ 35 V 1 Regline – 0.02 0.07 %/V Load Regulation (Note 2) 10 mA ≤ IL ≤ 3.0 A VO ≤ 5.0 V VO ≥ 5.0 V 2 Regload – – 20 0.3 70 1.5 mV % VO Temperature Stability (Tlow ≤ TJ ≤ Thigh) 3 TS – 1.0 – % VO Minimum Load Current to Maintain Regulation (VI–VO = 35 V) 3 ILmin – 3.5 10 mA Maximum Output Current VI–VO ≤ 10 V, PD ≤ Pmax VI–VO = 30 V, PD ≤ Pmax, TA = 25°C 3 Imax 3.0 0.25 4.5 1.0 – – – 0.003 – – 66 65 80 – – – 0.3 1.0 – – 2.3 – – 1.5 Characteristics Thermal Regulation, Pulse = 20 ms, (TA = +25°C) Adjustment Pin Current RMS Noise, % of VO TA= 25°C, 10 Hz ≤ f ≤ 10 kHz N Ripple Rejection, VO = 10 V, f = 120 Hz (Note 3) Without CAdj CAdj = 10 µF 4 Long Term Stability, TJ = Thigh (Note 4) TA= 25°C for Endpoint Measurements 3 Thermal Resistance, Junction–to–Case Peak (Note 5) Average (Note 6) A RR S % VO dB %/1.0 k Hrs. °C/W RθJC NOTES: 1. Tlow to Thigh = 0° to +125°C; Pmax = 25 W for LM350T; Tlow to Thigh = –40° to +125°C; Pmax = 25 W for LM350BT 2. Load and line regulation are specified at constant junction temperature. Changes in VO due to heating effects must be taken into account separately. Pulse testing with low duty cycle is used. 3. CAdj, when used, is connected between the adjustment pin and ground. 4. Since Long–Term Stability cannot be measured on each device before shipment, this specification is an engineering estimate of average stability from lot to lot. 5. Thermal Resistance evaluated measuring the hottest temperature on the die using an infrared scanner. This method of evaluation yields very accurate thermal resistance values which are conservative when compared to the other measurement techniques. 6. The average die temperature is used to derive the value of thermal resistance junction to case (average). http://onsemi.com 2 LM350 Representative Schematic Diagram 310 310 230 Vin 5.6K 120 6.3V 510 12.4K 30 pF 5.1K 110 5.8K 3.6K 30 pF 190 160 12K 5.0pF 6.8K 6.3V 135 125K 6.7K 170 13K 200 6.3V 2.4K 105 12.5K 4 0.45 Vout Adjust VCC Line Regulation (%/V) = * VIH VIL Vin Vout LM350 Adjust Cin *Pulse Testing Required: 1% Duty Cycleis suggested. 0.1µF IL R1 240 1% R2 1% Figure 1. Line Regulation and ∆IAdj/Line Test Circuit http://onsemi.com 3 x 100 VOH VOL CO IAdj VOH - VOL VOL + RL 1µF LM350 Load Regulation (% VO) = VO (min Load) - VO (max Load) VO (min Load) X 100 Load Regulation (mV) = VO (min Load) -VO (max Load) Vin Vin Vout LM350 IL Adjust Cin 0.1µF VO (min Load) VO (max Load) RL (max Load) 240 1% R1 + CO IAdj * RL (min Load) 1.0µF R2 1% *Pulse Testing Required: 1% Duty Cycle is suggested. Figure 2. Load Regulation and ∆IAdj/Load Test Circuit Vin Vout LM350 IL Adjust VI Cin 0.1µF 240 1% R1 IAdj Vref RL + CO 1.0µF VO ISET R2 1% To Calculate R2: Vout = ISET R2 + 1.250 V Assume ISET = 5.25 mA Pulse Testing Required: 1% Duty Cycle is suggested. Figure 3. Standard Test Circuit 24V 14V Vin f = 120 Hz LM350 Vout Adjust Cin Vout = 10 V IL 240 1% R1 0.1µF D1 * 1N4002 CO R2 ** CAdj 1.65K 1% + + RL 1.0µF 10µF *D1 Discharges CAdj if Output is Shorted to Ground. **CAdj provides an AC ground to the adjust pin. Figure 4. Ripple Rejection Test Circuit http://onsemi.com 4 VO 7 0.4 I out , OUTPUT CURRENT (A) ∆ Vout , OUTPUT VOLTAGE CHANGE (%) LM350 0.2 0 IL = 0.5 A -0.2 IL = 1.5 A -0.4 -0.6 Vin = 15 V Vout = 10 V -0.8 -1.0 -75 -50 -25 0 25 50 75 100 125 TJ, JUNCTION TEMPERATURE (°C) TJ = 55°C 5 TJ = 25°C 3 TJ = 150°C 1 0 150 0 10 20 30 Vin-Vout, INPUT VOLTAGE DIFFERENTIAL (Vdc) Figure 6. Current Limit 3.0 V in -Vout , INPUT-OUTPUT VOLTAGE DIFFERENTIAL (Vdc) IAdj, ADJUSTMENT PIN CURRENT (µA) Figure 5. Load Regulation 70 65 60 55 50 45 40 35 -75 -50 -25 0 25 50 75 100 125 TJ, JUNCTION TEMPERATURE (°C) IL = 3.0 A IL = 2.0 A 2.0 IL = 500 mA 1.5 1.0 -75 150 ∆V0 = 100 mV 2.5 Figure 7. Adjustment Pin Current IL = 200 mA IL = 20 mA -50 -25 0 25 50 75 100 125 TJ, JUNCTION TEMPERATURE (°C) 150 Figure 8. Dropout Voltage 1.260 5.0 IB , QUIESCENT CURRENT (mA) Vref , REFERENCE VOLTAGE (V) 40 1.250 1.240 1.230 4.5 TJ = -55°C 4.0 TJ = 25°C 3.5 3.0 TJ = 150°C 2.5 2.0 1.5 1.0 0.5 1.220 -75 -50 -25 0 25 50 75 100 125 TJ, JUNCTION TEMPERATURE (°C) 0 150 0 Figure 9. Temperature Stability 10 20 30 40 Vin-Vout, INPUT-OUTPUT VOLTAGE DIFFERENTIAL (Vdc) Figure 10. Minimum Operating Current http://onsemi.com 5 LM350 100 140 RR, RIPPLE REJECTION (dB) RR, RIPPLE REJECTION (dB) CAdj = 10 µF 80 Without CAdj 60 40 Vin - Vout = 5 V IL = 500 mA f = 120 Hz TJ = 25°C 20 0 0 5 10 15 20 25 30 Vout, OUTPUT VOLTAGE (V) 120 100 60 40 20 0 0.01 35 Figure 11. Ripple Rejection versus Output Voltage 0.1 1 Iout, OUTPUT CURRENT (A) IL = 500 mA Vin = 15 V Vout = 10 V TJ = 25°C 80 60 40 CAdj = 10 µF Without CAdj 20 100 1.0 k 10 k 100 k 1.0 M f, FREQUENCY (Hz) 100 10-1 Without CAdj 10-2 10-3 10 M Vin = 15 V Vout = 10 V IL = 500 mA TJ = 25°C CAdj = 10 µF 10 100 ∆ Vout , OUTPUT VOLTAGE DEVIATION (V) 1.5 1.0 CL = 1.0 µF; CAdj = 10 µF 0.5 1.0 k 10 k f, FREQUENCY (Hz) 100 k 0 3 2 1 CL = 1.0 µF; CAdj = 10 µF 0 Vin = 15 V Vout = 10 V INL = 50 mA TJ = 25°C -1 -0.5 -2 Vout = 10 V IL = 50 mA TJ = 25°C -1.0 -1.5 1.0 1.5 CL = 0; Without CAdj 1.0 Vin 0 10 CL = 0; Without CAdj -3 0.5 20 IL 0.5 30 1.0 M Figure 14. Output Impedance I L , LOAD CURRENT (A) ∆ Vin , INPUT VOLTAGE CHANGE (V) ∆ Vout , OUTPUT VOLTAGE DEVIATION (V) Figure 13. Ripple Rejection versus Frequency 0 10 101 Z O , OUTPUT IMPEDANCE ( Ω) RR, RIPPLE REJECTION (dB) Without CAdj Vin - Vout = 5 V IL = 500 mA f = 120 Hz TJ = 25°C Figure 12. Ripple Rejection versus Output Current 100 0 10 CAdj = 10 µF 80 40 0 t, TIME (µs) 20 t, TIME (µs) Figure 15. Line Transient Response Figure 16. Load Transient Response http://onsemi.com 6 0 10 30 40 LM350 APPLICATIONS INFORMATION Basic Circuit Operation External Capacitors The LM350 is a three–terminal floating regulator. In operation, the LM350 develops and maintains a nominal 1.25 V reference (Vref) between its output and adjustment terminals. This reference voltage is converted to a programming current (IPROG) by R1 (see Figure 17), and this constant current flows through R2 to ground. The regulated output voltage is given by: A 0.1 µF disc or 1 µF tantalum input bypass capacitor (Cin) is recommended to reduce the sensitivity to input line impedance. The adjustment terminal may be bypassed to ground to improve ripple rejection. This capacitor (CAdj) prevents ripple from being amplified as the output voltage is increased. A 10 µF capacitor should improve ripple rejection about 15 dB at 120 Hz in a 10 V application. Although the LM350 is stable with no output capacitance, like any feedback circuit, certain values of external capacitance can cause excessive ringing. An output capacitance (CO) in the form of a 1 µF tantalum or 25 µF aluminum electrolytic capacitor on the output swamps this effect and insures stability. Vout = Vref (1 + R2 ) + IAdj R2 R1 Since the current from the terminal (IAdj) represents an error term in the equation, the LM350 was designed to control IAdj to less than 100 µA and keep it constant. To do this, all quiescent operating current is returned to the output terminal. This imposes the requirement for a minimum load current. If the load current is less than this minimum, the output voltage will rise. Since the LM350 is a floating regulator, it is only the voltage differential across the circuit which is important to performance, and operation at high voltages with respect to ground is possible. Vin LM350 When external capacitors are used with any IC regulator, it is sometimes necessary to add protection diodes to prevent the capacitors from discharging through low current points into the regulator. Figure 18 shows the LM350 with the recommended protection diodes for output voltages in excess of 25 V or high capacitance values (CO > 25 µF, CAdj > 10 µF). Diode D1 prevents CO from discharging thru the IC during an input short circuit. Diode D2 protects against capacitor CAdj discharging through the IC during an output short circuit. The combination of diodes D1 and D2 prevents CAdj from discharging through the IC during an input short circuit. Vout + Vref Adjust Protection Diodes R1 IPROG Vout IAdj R2 D1 Vref = 1.25 V Typical 1N4002 Vin Figure 17. Basic Circuit Configuration Load Regulation LM350 Cin The LM350 is capable of providing extremely good load regulation, but a few precautions are needed to obtain maximum performance. For best performance, the programming resistor (R1) should be connected as close to the regulator as possible to minimize line drops which effectively appear in series with the reference, thereby degrading regulation. The ground end of R2 can be returned near the load ground to provide remote ground sensing and improve load regulation. Vout R1 + D2 Adjust 1N4002 R2 CAdj Figure 18. Voltage Regulator with Protection Diodes http://onsemi.com 7 CO LM350 D6 1N4002 Vin 32V Vout1 RSC LM350 (1) Vin1 Vin2 IO Vout 2 LM350 (2) VO 240 0.1µF D1 1N4001 Adjust 1 1K Current Limit Adjust Adjust 2 1N4001 D2 5.0K Q1 2N3822 + D5 IN4001 + 1.0µF Tantalum 10µF Voltage Adjust 1N4001 D3 D4 -10V Q2 2N5640 Diodes D1 and D2 and transistor Q2 are added to allow adjustment of output voltage to 0 V. Output Range: 0 ≤ VO ≤ 25 V 0 ≤ IO ≤ 1.5 A 1N4001 -10V D6 protects both LM350's during an input short circuit. Figure 19. “Laboratory” Power Supply with Adjustable Current Limit and Output Voltage +25V Vout LM350 Vin Vout R1 Iout 620 Adjust D1 D1 1N4001 R2 100 * To provide current limiting of IO to the system ground, the source of the FET must be tied to a negative voltage below -1.25 V. Vref R2 ≤ IDSS Vref R1 = IOmax + IDSS Vin D2 1N4001 Adjust 2N5640 1.0µF 1.0k VSS* TTL Control Minimum Vout = 1.25 V D1 protects the device during an input short circuit. Figure 21. 5.0 V Electronic Shutdown Regulator Vin Vout 240 Adjust 1N4001 50k MPS2907 Vout LM350 Adjust R2 + MPS2222 720 Figure 20. Adjustable Current Limiter LM350 Vout LM350 120 VO < V(BR)DSS + 1.25 V + VSS ILmin - IDSS < IO < 3.0 A As shown O < IO < 1.0 A Vin 1N4002 IAdj Iout + 10µF R1 VRref1 IAdj 1.25 V R1 10 mA ≤ Iout ≤ 3.0 A Figure 22. Slow Turn–On Regulator Figure 23. Current Regulator http://onsemi.com 8 Iout LM350 PACKAGE DIMENSIONS T SUFFIX PLASTIC PACKAGE CASE 221A–09 ISSUE AA –T– B SEATING PLANE C F T S 4 DIM A B C D F G H J K L N Q R S T U V Z A Q 1 2 3 U H K Z L R V NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION Z DEFINES A ZONE WHERE ALL BODY AND LEAD IRREGULARITIES ARE ALLOWED. J G D N http://onsemi.com 9 INCHES MIN MAX 0.570 0.620 0.380 0.405 0.160 0.190 0.025 0.035 0.142 0.147 0.095 0.105 0.110 0.155 0.018 0.025 0.500 0.562 0.045 0.060 0.190 0.210 0.100 0.120 0.080 0.110 0.045 0.055 0.235 0.255 0.000 0.050 0.045 ----0.080 MILLIMETERS MIN MAX 14.48 15.75 9.66 10.28 4.07 4.82 0.64 0.88 3.61 3.73 2.42 2.66 2.80 3.93 0.46 0.64 12.70 14.27 1.15 1.52 4.83 5.33 2.54 3.04 2.04 2.79 1.15 1.39 5.97 6.47 0.00 1.27 1.15 ----2.04 LM350 Notes http://onsemi.com 10 LM350 Notes http://onsemi.com 11 LM350 ON Semiconductor and are trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. 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