TIGER ELECTRONIC CO.,LTD 3-TERMINAL ADJUSTABLE REGULATOR LM317L / LM317LF DESCRIPTION The LM317 is an adjustable 3-terminal positive voltage regulator capable of supplying 100mA over a 1.2V to 37V output range. It 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 comp ensation, making it essentially blow-out proof. Also, the LM317 is available packaged in a standard TO-92 transistor package which is easy to use. The LM317 serves a wide variety of applications including local, on card regulation. This device can also be used to make a programmable output regulator, or by connecting a fixed resistor between the adjustment and output, the LM317 can be used as a precision current regulator. FEATURES PIN CONNECTION Adjustable output down to 1.2V Guaranteed 100 mA output current Line regulation typically 0.01%/V Load regulation typically 0.1% Current limit constant with temp erature Eliminates the need to stock many voltages 80 dB ripple rejection Output is short circuit protected LM317L LM317LF 1/14 LM317 SCHEMATIC DIAGRAM 2/14 LM317 ABSOLUTE MAXIMUM RATINGS (Ta=25°C) Characteristic Input-Output Voltage Differential Symbol Vi/Ao Min. -0.3 PD - Tj TL Tstg -25 -55 Power Dissipation Operating Junction Temp erature Range Lead Temperature (Soldering, 4 seconds) Storage Temp erature Range Max. 40 Internally Limited 125 250 150 Unit V W °C °C °C ELECTRICAL CHARACTERISTICS (unless otherwise specified: Vi-Vo=5.0V; Io=40mA; Tj=0~125°C; Imax=100mA and Pmax=625mW ) Characteristics Line Regulation Load Regulation Adjustment Pin Current Adjustment Pin Current Change Reference Voltage Line Regulation Load Regulation Te mp erature Stability Minimu m Current Load Current Limit Rms Noise % of Vo Ripple Rejection Long-Term Stability Test conditions Symbol Min. Typ. Max. Unit Regline - 0.01 0.05 % /V Tj=25℃ , 5mA≤ I O U T ≤ I M A X Regload - 0.1 0.5 % - 50 100 μA 0.2 6 μA 1.25 1.35 V 0.02 0.05 %/V 0.3 1.2 % - 0.65 - % - 3.5 17 1.5 6 40 200 260 mA 25 50 70 mA - 0.003 0.008 % 65 80 Tj=25℃ , I L ≤ 20mA 3 V≤ (V I N -V O U T )≤ 40V - Iadj 5 mA≤ I L ≤ 100mA 3 V≤ (V I N -V O U T ) ≤ 40V, ∆ Iadj P≤ 625mW 3 V≤ (V I N -V O U T ) ≤ 40V, 5 mA≤ I O U T ≤ 100mA, Vref 1.15 P≤ 625mW 3 V ≤ (V I N - V O U T ) ≤ 40V,I ≤ Regline 20mA Regload 5 mA≤ I O U T ≤ 100mA T M I N ≤ Tj≤ T M A X (V I N -V O U T ) ≤ 40V 3 V≤ (V I N -V O U T ) ≤ 15V 3 V≤ (V I N -V O U T ) ≤ 13V (V I N -V O U T ) =40V Tj=25℃ , 10Hz≤ f≤ 10KHz V O U T =10V, f=120Hz, C A D J =0 C A D J =10μ F Tj=125℃ , 1000Hours Ts I L min Imax N RR S 66 80 - 0.3 1 mA dB % 3/14 LM317 APPLICATION INFORMATION 1. Basic circuit operation In operation, the LM317 develops a nominal 1.25V reference voltage, Vref, between the output and adjustment terminal. The reference voltage is impressed across program resistor R1 and, since the voltage is constant, a constant current I1 then flows through the output set resistor R2, giving an output voltage of Vo u t=Vref(1 +R2 /R1 )+Iad j* (R2 ) Since the 100µA current from the adjustment VIN terminal represents an error term, the LM317 LLW317L VOU ADJ was designed to minimize Iadj and make it very I1 VRE R1 VOU constant with line and load changes. To do this, I AD all quiescent operating current is returned to the R2 J output establishing a minimu m load current requirement. If there is insufficient load on the output, the output will rise. Figure: Basic circuit configuration 2. Load Regulation The LM317 is capable of providing extremely good load regulation, but a few precautions are needed to performance. For best obtain maxi mu m performance, the programmi ng resistor (R1) should be connected as close to the regulator as possible to VIN LM317L W317L VIN VOUT ADJ mini mize line drops which effectiv ely appear in Rs VOUT R1 240 series with the reference, thereb y degradin g regulation. The ground end of R2 can be R2 returned near the load ground to provide remo te ground sensing and improve load regu lation in Regu lato r with line resistance o u tpu t lead 3.External capacitors A 0.1 µF disc or 1.0 µF tantalum input bypass capacitor (Cin) is reco mmended to reduce the sensitivity to input line impedance. Th e adju stment terminal ma y be bypassed to grou nd to impro v e ripple rejectio n. This capacitor (Cadj) prevents ripple from being amplified as the output vo ltage is increased. A 10µF capacitor should improve ripple rejection ab ou t 15dB at 120Hz in a 4/14 LM317 10V application. Although th e LM317 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 1.0µF tantalum or 25 µF aluminu m ele ctrolytic capacitor on the output swamps this effect and insures stability. 4. Protection Diodes 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. Most 10µF capacitors have low enough internal series resistance to deliver 20A spikes wh en shorted. Although the surge is short, there is enough energy to damage parts of the IC. When an output capacitor is connected to a regulator and the input is shorted, the output capacitor will discharge into the output of the regulator. The discharge current depends on the value of the capacitor, the output voltage of the regulator, and the rate of decrease of Vin . In the LM317, this discharge path is through a large junction that is able to sustain a 2A surge with no problem. This is not true of other types of positive regulators. For output capacitors of 25µF or less, the LM317’s ballast resistors and output structure limit the peak current to a low enough level so that there is no need to use a protection diode. The bypass capacitor on the adjustment terminal can discharge through a low current junction. Discharge occurs when D1 either the input or output is shorted. Internal to the LM317 is a 50Ω resistor which limits the peak discharge current. No protection is needed for output voltages of 25V or less and VIN VIN IN400 LM317L W317L VOU ADJ VOU D2 T IN400 T R1 240 C1 10µF capacitance. Figure in right shows an LM 317 with protection diodes included for R2 10u + C2 use with outputs greater than 25V and high values of output capacitance. Regulator with protection diodes 5/14 LM317 APPLICATION CIRCUIT *Sets maximum Vout Dig itally Selected Ou tp uts Hig h Gain Amp lifier 12 ≤ R1 ≤ 240 Ad ju stable Cu rren t Limiter Slow Turn-on 15V Regulator Improved Ripple Rejection Precisio n Cu rren t Limiter +Sold tantalum * D i s c h a rg e s C 1 i f o u t p u t i s s h o r t e d t o g r o u n d Adju stab le Reg u lato r with 6/14 LM317 Short circuit current is approximately 600mV/R3, At 25mA output only 3/4V of drop occurs in R3 and R4 High Stability 10V Regulator 0 V~3 0V Reg ulato r Adjustable Regulator with Current Limiter Cu rren t Po wer Fo llo wer Adjusting Multiple on-Card Regulators with Single Control 7/14 LM317 *Minimum load current=2mA 100mA Current Regulator 1.2V~12V Regulator with 50mA constant Current Min imu m Pro g ram Cu rren t Battery Ch arg er for Nick el-Cad miu m Batteries * Min imu m ou tp u t=1.2 V * Sets p eak cu rrent, Ip eak =0 .6 V/R1 **1000µF is recommended to filter out any input transients 5V Logic Regulator with Electronic Shutdown Current Limited 6V Charger 8/14 LM317 Short Circuit Protected 80V Supply Q1,Q2:NSD134 or similar C 1 , C 2 : 1 µ F, 2 0 0 V m y l a r * * *Heat sink Basic High Vo ltage Regulator 9/14 LM317 Q1,Q2:NSD134 or similar C 1 , C 2 : 1 µ F, 2 0 0 V m y l a r * * * H e a t s i n k * * M y l a r i s a r e g i s t e r e d t r a d e m a r k o f D u P o n t C o . Precision High Vo ltage Regulator Tracking Regulator Regulator with Trimmable output Voltage 10/14 LM317 Precision Reference with Short-Circuit Proof Output Ad ju stab le Reg u lato r Pro tected (Bu lletp ro o f) Lamp Flash er Lamp Driv er 11/14 LM317 CHARACTERISTICS CURVES 12/14 LM317 Precision Reference with Short-Circuit Proof Output Ad ju stab le Reg u lato r Pro tected (Bu lletp ro o f) Lamp Flash er Lamp Driv er 11/14 LM317 OUTLINE DRAWING TO-9 2 SOT-89-3L Un it:mm Unit:mm 14/14