THREE-TERMINAL ADJUSTABLE POSITIVE VOLTAGE REGULATOR

Order this document by LM350/D LM350 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 THREE–TERMINAL ADJUSTABLE POSITIVE VOLTAGE REGULATOR SEMICONDUCTOR TECHNICAL DATA T SUFFIX PLASTIC PACKAGE CASE 221A • • • • • • • • • 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 1 2 3 Pin 1. Adjust 2. Vout 3. Vin Heatsink surface is connected to Pin 2. Simplified Application Vin vout R1 240 IAdj Cin* 0.1µF R2 Adjust + C ** O 1µF LM350 ORDERING INFORMATION Device * = 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. Vout LM350T LM350BT# Operating Temperature Range TJ = 0° to +125°C TJ = –40° to +125°C Package Plastic Power Plastic Power + 1.25 V 1 ) R2 ) IAdj R2 R1 Since IAdj is controlled to less than 100 µA, the error associated with this term is negligible in most applications. # Automotive temperature range selections are available with special test conditions and additional tests. Contact your local Motorola sales office for information. © Motorola, Inc. 1996 Rev 0 MOTOROLA ANALOG IC DEVICE DATA 1 LM350 MAXIMUM RATINGS Rating Input–Output Voltage Differential Power Dissipation Operating Junction Temperature Range Storage Temperature Range Soldering Lead Temperature (10 seconds) Symbol VI–VO PD TJ Tstg Tsolder Value 35 Internally Limited – 40 to +125 – 65 to +150 300 Unit Vdc W °C °C °C ELECTRICAL CHARACTERISTICS (VI–VO = 5.0 V; IL = 1.5 A; TJ = Tlow to Thigh; Pmax [Note 1], unless otherwise noted.) Characteristics Line Regulation (Note 2) TA = 25°C, 3.0 V ≤ VI–VO ≤ 35 V Load Regulation (Note 2) TA = 25°C, 10 mA ≤ Il ≤ 3.0 A VO ≤ 5.0 V VO ≥ 5.0 V Thermal Regulation, Pulse = 20 ms, (TA = +25°C) Adjustment Pin Current Adjustment Pin Current Change 3.0 V ≤ VI–VO ≤ 35 V 10 mA ≤ IL ≤ 3.0 A, PD ≤ Pmax Reference Voltage 3.0 V ≤ VI–VO ≤ 35 V 10 mA ≤ IO ≤ 3.0 A, PD ≤ Pmax Line Regulation (Note 2) 3.0 V ≤ VI–VO ≤ 35 V Load Regulation (Note 2) 10 mA ≤ IL ≤ 3.0 A VO ≤ 5.0 V VO ≥ 5.0 V Temperature Stability (Tlow ≤ TJ ≤ Thigh) Minimum Load Current to Maintain Regulation (VI–VO = 35 V) Maximum Output Current VI–VO ≤ 10 V, PD ≤ Pmax VI–VO = 30 V, PD ≤ Pmax, TA = 25°C RMS Noise, % of VO TA= 25°C, 10 Hz ≤ f ≤ 10 kHz Ripple Rejection, VO = 10 V, f = 120 Hz (Note 3) Without CAdj CAdj = 10 µF Long Term Stability, TJ = Thigh (Note 4) TA= 25°C for Endpoint Measurements Thermal Resistance, Junction–to–Case Peak (Note 5) Average (Note 6) 4 3 1,2 Figure 1 2 Symbol Regline Regload – – Regtherm IAdj ∆IAdj – – – 5.0 0.1 0.002 50 0.2 25 0.5 – 100 5.0 mV % VO % VO/W µA µA Min – Typ 0.0005 Max 0.03 Unit %/V 3 Vref 1.20 1.25 1.30 V 1 2 Regline Regload – 0.02 0.07 %/V – – 3 3 3 TS ILmin Imax 3.0 0.25 N RR – 66 3 S RθJC – – – – 20 0.3 1.0 3.5 70 1.5 – 10 mV % VO % VO mA A 4.5 1.0 0.003 – – – % VO dB 65 80 0.3 – – 1.0 %/1.0 k Hrs. °C/W – – 2.3 – – 1.5 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). 2 MOTOROLA ANALOG IC DEVICE DATA LM350 Representative Schematic Diagram Vin 310 310 230 120 5.6K 6.3V 170 6.7K 12K 5.0pF 6.8K 510 160 200 13K 6.3V 125K 6.3V 135 12.4K 30 pF 3.6K 5.8K 5.1K 110 30 pF 2.4K 12.5K 105 4 190 0.45 Vout Adjust Figure 1. Line Regulation and ∆IAdj/Line Test Circuit VCC Line Regulation (%/V) = * VIH VIL Vin LM350 Vout IL VOH – VOL x 100 VOL VOH VOL Adjust Cin 0.1µF IAdj R1 240 1% CO RL + 1µF * Pulse Testing Required: 1% Duty Cycle is suggested. R2 1% MOTOROLA ANALOG IC DEVICE DATA 3 LM350 Figure 2. Load Regulation and ∆IAdj/Load Test Circuit Load Regulation (% VO) = VO (min Load) – VO (max Load) X 100 VO (min Load) Load Regulation (mV) = VO (min Load) –VO (max Load) Vout IL RL (max Load) * + Cin 0.1µF IAdj CO 1.0µF Vin Vin VO (min Load) VO (max Load) LM350 Adjust R1 240 1% RL (min Load) R2 1% * Pulse Testing Required: 1% Duty Cycle is suggested. Figure 3. Standard Test Circuit Vin Vout LM350 IL Adjust VI Cin 0.1µF ISET R2 1% R1 IAdj 240 1% Vref + CO 1.0µF RL VO Pulse Testing Required: 1% Duty Cycle is suggested. To Calculate R2: Vout = ISET R2 + 1.250 V Assume ISET = 5.25 mA Figure 4. Ripple Rejection Test Circuit 24V 14V f = 120 Hz Vin LM350 Vout IL Vout = 10 V Adjust Cin 0.1µF R1 240 1% D1 * 1N4002 + CO 1.0µF RL VO R2 1.65K 1% ** CAdj + 10µF * D1 Discharges CAdj if Output is Shorted to Ground. **CAdj provides an AC ground to the adjust pin. 4 MOTOROLA ANALOG IC DEVICE DATA LM350 Figure 5. Load Regulation ∆ Vout , OUTPUT VOLTAGE CHANGE (%) 0.4 I out , OUTPUT CURRENT (A) 0.2 0 –0.2 –0.4 –0.6 –0.8 –1.0 –75 –50 –25 0 25 50 75 100 125 150 Vin = 15 V Vout = 10 V IL = 1.5 A IL = 0.5 A 7 TJ = 55°C 5 TJ = 25°C TJ = 150°C Figure 6. Current Limit 3 1 0 0 10 20 30 40 TJ, JUNCTION TEMPERATURE (°C) Vin–Vout, INPUT VOLTAGE DIFFERENTIAL (Vdc) Figure 7. Adjustment Pin Current 3.0 IAdj, ADJUSTMENT PIN CURRENT ( µA) 70 65 60 55 50 45 40 35 –75 –50 –25 0 25 50 75 100 125 150 V in –Vout , INPUT–OUTPUT VOLTAGE DIFFERENTIAL (Vdc) Figure 8. Dropout Voltage ∆V0 = 100 mV IL = 3.0 A IL = 2.0 A 2.0 IL = 500 mA 1.5 IL = 20 mA –50 –25 0 25 50 75 100 TJ, JUNCTION TEMPERATURE (°C) IL = 200 mA 125 150 2.5 1.0 –75 TJ, JUNCTION TEMPERATURE (°C) Figure 9. Temperature Stability 1.260 Vref, REFERENCE VOLTAGE (V) IB , QUIESCENT CURRENT (mA) 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 1.220 –75 –50 –25 0 25 50 75 100 125 150 0 0 Figure 10. Minimum Operating Current TJ = –55°C TJ = 25°C TJ = 150°C 1.250 1.240 1.230 10 20 30 40 TJ, JUNCTION TEMPERATURE (°C) Vin–Vout, INPUT–OUTPUT VOLTAGE DIFFERENTIAL (Vdc) MOTOROLA ANALOG IC DEVICE DATA 5 LM350 Figure 11. Ripple Rejection versus Output Voltage 100 CAdj = 10 µF RR, RIPPLE REJECTION (dB) 80 60 40 20 0 Without CAdj RR, RIPPLE REJECTION (dB) Figure 12. Ripple Rejection versus Output Current 140 120 100 80 60 40 20 Vin – Vout = 5 V IL = 500 mA f = 120 Hz TJ = 25°C 0.1 1 Iout, OUTPUT CURRENT (A) 10 CAdj = 10 µF Without CAdj Vin – Vout = 5 V IL = 500 mA f = 120 Hz TJ = 25°C 0 5 10 15 20 25 30 Vout, OUTPUT VOLTAGE (V) 35 0 0.01 Figure 13. Ripple Rejection versus Frequency 100 RR, RIPPLE REJECTION (dB) 80 60 40 CAdj = 10 µF 20 0 10 Without CAdj IL = 500 mA Vin = 15 V Vout = 10 V TJ = 25°C Z O , OUTPUT IMPEDANCE ( Ω ) 101 Figure 14. Output Impedance Vin = 15 V Vout = 10 V IL = 500 mA TJ = 25°C 100 10–1 Without CAdj 10–2 CAdj = 10 µF 100 1.0 k 10 k 100 k 1.0 M f, FREQUENCY (Hz) 10 M 10–3 10 100 1.0 k 10 k f, FREQUENCY (Hz) 100 k 1.0 M ∆ Vout , OUTPUT VOLTAGE DEVIATION (V) Figure 15. Line Transient Response ∆ Vout , OUTPUT VOLTAGE DEVIATION (V) 3 2 1 0 –1 –2 –3 1.5 1.0 0.5 0 –0.5 –1.0 –1.5 1.0 0.5 0 0 10 20 t, TIME (µs) Vin 30 40 Vout = 10 V IL = 50 mA TJ = 25°C CL = 1.0 µF; CAdj = 10 µF Figure 16. Load Transient Response CL = 1.0 µF; CAdj = 10 µF Vin = 15 V Vout = 10 V INL = 50 mA TJ = 25°C ∆ Vin , INPUT VOLTAGE CHANGE (V) CL = 0; Without CAdj I L , LOAD CURRENT (A) CL = 0; Without CAdj 1.5 1.0 0.5 0 0 10 20 t, TIME (µs) IL 30 40 6 MOTOROLA ANALOG IC DEVICE DATA LM350 APPLICATIONS INFORMATION Basic Circuit Operation 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: External Capacitors 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 rippl