TS2938/A 500mA Ultra Low Dropout Fixed Voltage Regulator with Inhibit Pin assignment: 1. Input 2. Inhibit 3. Gnd 4. N/C 5. Output Low Dropout Voltage 0.6V max. Logic Inhibit Control Pin assignment: 1. Output 8. Input 2. Gnd 7. Gnd 3. Gnd 6. Gnd 4. N/C 5. Inhibit General Description The TS2938/A series of fixed-voltage monolithic micro-power voltage regulators is designed for a wide range of applications. This device excellent choice of use in battery-power application. Furthermore, the quiescent current increases on slightly at dropout, which prolongs battery life. This series of fixed-voltage regulators features very low ground current (100uA Typ.), very low drop output voltage (Typ. 60mV at light load and 600mV at 500mA) and output inhibit control. This includes a tight initial tolerance of 1% (TS2938A) and 2% (TS2938), extremely good line regulation of 0.05% typ., and very low output temperature coefficient. This series is offered in 5-pin of TO-252-5L and 8-pin SOP-8 package. Features Dropout voltage typically 0.5V @Io=500mA Output current up to 500mA Logic control electronic shutdown Output voltage trimmed before assembly -18V Reverse peak voltage +30V Input over voltage protection +60V Transient peak voltage Low quiescent current 100uA typ. (ON mode), Internal current limit Thermal shutdown protection Ordering Information Block Diagram Part No. Operation Temp. Package (Ambient) TS2938CP5xx TO-252-5L -20 ~ +85 oC TS2938ACP5xx TS2938CSxx SOP-8 TS2938ACSxx Note: Where xx denotes voltage option, available are 8.0V, 5.0V, 3.3V and 2.5V. Contact factory for additional voltage options. Absolute Maximum Rating (Note 1) Input Supply Voltage (Note 2) Operation Input Supply Voltage Vin -18 ~ +60 V Vin (operate) 26 V PD Internally Limited Power Dissipation (Note 3) Operating Junction Temperature Range TJ Storage Temperature Range TSTG W -40 ~ +125 o C -65 ~ +150 o C o Lead Soldering Temperature (260 C) TO-252 / SOP-8 Package TS2938/A 5 1-5 S 2004/09 rev. A Electrical Characteristics Vin = Vout + 1V, IL = 5mA, Co = 6.8uF, Ta = 25 oC, Vinhibit = 0V, unless otherwise specified. Parameter Output Voltage Output Voltage Conditions o Ta = 25 C Ta = -25 ~ 85 oC Min Typ Max Unit TS2938A 0.990|Vo| 8.0 / 5.0 1.010|Vo| v TS2938 0.980|Vo| 3.3 / 2.5 1.020|Vo| V TS2938A 0.980|Vo| TS2938 0.960|Vo| 1.020|Vo| 1.040|Vo| V Input Supply Voltage -- -- 26 V Output Voltage Temp. Coefficient -- 50 150 ppm/ oC Line Regulation Vo+1V ≤ Vin ≤ 26V -- 0.05 0.5 % Load Regulation 5mA ≤ IL ≤ 500mA -- 0.2 1.0 % Dropout Voltage (Note 4) IL=100mA -- 100 200 IL=300mA -- 300 400 IL=500mA -- 500 600 Quiescent Current (Note 5) mV IL=100uA -- 100 200 uA IL=300mA -- 12 20 mA IL=500mA -- 25 50 Short Circuit Current (Note 6) Vout=0 -- 0.9 1.3 Output Noise, CL=2.2uF -- 500 -- 10Hz to 100KHz, IL=10mA CL=3.3uF -- 350 -- CL=33uF -- 120 -- Io=350mA, f=120Hz, 60 -- -- dB -- 1.3 0.7 V 2.0 -- -- Ripple Rejection Ratio A uVrms Co=100uF, Vin=Vo+3V+2Vpp Shutdown Input Input Logic Voltage Low (Regulator ON) High (Regulator OFF) Shutdown Pin Input Current Vinhibit = 2.4V -- 30 50 Vinhibit = 26V -- 450 600 Regulator Output Current in Vinhibit ≤ 2V, Vin ≤ 26V, -- -- 200 Shutdown Vout = 0V uA Thermal Performance Condition Thermal Resistance Package type Typ Unit o TO-252 150 C/W SOP-8 170 Note 1: Absolute Maximum Rating is limits beyond which damage to the device may occur. For guaranteed Specifications and test conditions see the Electrical Characteristics. Note 2: Maximum positive supply voltage of 60V must be limited duration (<100mS) and duty cycle (<1%). Note 3: The maximum allowable power dissipation is a function of the maximum junction temperature, Tj, the junction to ambient thermal resistance, θja, and the ambient temperature, Ta. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. The effective value of θja can be reduced by using a heatsink. Note 4: Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1V differential. Note 5: Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the ground pin current and output load current. Note 6: Output current will decrease with increasing temperature, but it will be not dropped below 500mA at the maximum specified temperature. Junction to Ambient TS2938/A 2-5 2004/09 rev. A Application Information The TS2938/A series is a high performance with low dropout voltage regulator suitable for moderate to high current and voltage regulator application. Its 500Mv (typ) dropout voltage at full load and over temperature makes it especially valuable in battery power systems and as high efficiency noise filters in post regulator applications. Unlike normal NPN transistor design, where the base to emitter voltage drop and collector to emitter saturation voltage limit the minimum dropout voltage, dropout performance of the PNP output of these devices is limited only by low Vce saturation voltage. The TS2938/A series is fully protected from damage due to fault conditions. Linear current limiting is provided. Output current during overload conditions is constant. Thermal shutdown the device when the die temperature exceeds the maximum safe operating temperature. Transient protection allows device survival even when the input voltage spikes above and below nominal. The output structure of these regulators allows voltages in excess of the desired output voltage to be applied without reverse current flow. Typical Application Circuit good transient response and stability over temperature. Aluminum electrolytic can also be used, as long as the ESR of the capacitor is <2ohm. The value of the output capacitor can be increased without limit. Higher capacitance values help to improved transient response and ripple rejection and reduce output noise. Minimum Load Current The TS2938/A series is specified between finite loads. If the output current is too small leakage currents dominate and the output voltage rises. A 5mA minimum load current is necessary for proper regulation. Input Capacitor An input capacitor of 1uF or greater is recommended when the device is more that 4 inches away from the bulk AC supply capacitance or when the supply is a battery. Small and surface mount ceramic chip capacitors can be used for bypassing. Larger values will help to improve ripple rejection by bypassing the input to the regulator, further improving the integrity of the output voltage. Thermal Characteristics Output Capacitor The TS2938/A series requires an output capacitor to maintain stability and improve transient response. Proper capacitor selection is important to ensure proper operation. The output capacitor selection is dependent upon the ESR of the output capacitor the maintain stability. When the output capacitor is 6.8uF or greater, the output capacitor should have an ESR less than 2 ohm. This will improve transient response as well as promoted stability. Ultra low ESR capacitors (<100mohm), such as ceramic chip capacitors may promote instability. These very low ESR levels may cause an oscillation and/or under damped transient response. A low ESR solid tantalum capacitor works extremely well and provide A heatsink may be required depending on the maximum power dissipation and maximum ambient temperature of the application. Under all possible operating conditions, the junction temperature must be within the range specified under absolute maximum ratings. To determine if the heatsink is required, the power dissipated by the regulator, PD must be calculated. The below formula shows the voltages and currents for calculating the PD in the regulator: Iin = IL / IG PD = (Vin-Vout) * IL + (Vin) * IG Ex. PD = (3.3V-2.5V) * 0.5A + 3.3V * 11mA = 400mW + 36mW = 436mW Remark: IL is output load current, IG is ground current. Vin is input voltage Vout is output voltage TS2938/A 3-5 2004/09 rev. A Application Information (continued) The next parameter which must be calculated the maximum allowable temperature rise. TR(max) is calculated by the using to formula: TR(max) = TJ(max) – TA(max) Where: TJ(max) is the maximum allowable junction o temperature, which is 125 C for commercial grade parts.TA(max) is the maximum ambient temperature which will be encountered in the application. Using the calculated values for TR(max) and PD, the maximum allowable value for the junction to ambient thermal resistance, θja, can now be found: θja = TR(max) / PD Inhibit Input TS2938/A feature an active-low (Inhibit) input that allows ON/OFF control of the regulator. The Inhibit input has TTL/CMOS compatible thresholds for simple interfacing with logic interfacing. Inhibit should be directly tied to Ground or keep open (not connected). IMPORTANT: if the maximum allowable value for is found to be ≥ 60 o C/W for the TO-220 package, ≥80 oC/W for the o TO-263 package, ≥150 C/W for the TO-252 package, o or ≥170 C/W for the SOT-223 package, no heatsink is needed since the package alone will dissipate enough heat to satisfy these requirements. If the calculated value for θja falls below these limits, a heatsink is required. TS2938/A 4-5 2004/09 rev. A SOP-8 Mechanical Drawing A DIM 9 16 B 1 P 8 G R C D M F K A B C D F G K M P R SOP-8 DIMENSION MILLIMETERS INCHES MIN MAX MIN MAX 4.80 5.00 0.189 0.196 3.80 4.00 0.150 0.157 1.35 1.75 0.054 0.068 0.35 0.49 0.014 0.019 0.40 1.25 0.016 0.049 1.27 (typ) 0.05 (typ) 0.10 0.25 0.004 0.009 0o 7o 0o 7o 5.80 6.20 0.229 0.244 0.25 0.50 0.010 0.019 TO-252-5L Mechanical Drawing DIM TS2938/A 5-5 TO-252-5L DIMENSION MILLIMETERS INCHES A B C D E MIN 6.350 9.250 0.460 2.560 2.190 MAX 6.730 10.400 0.640 2.670 2.380 MIN 0.2509 0.364 0.018 0.101 0.086 MAX 0.265 0.409 0.025 0.105 0.094 F G H I J 0.460 1.400 0.460 5.340 1.520 0.570 1.780 0.570 5.550 2.030 0.018 0.055 0.018 0.210 0.060 0.022 0.070 0.022 0.219 0.080 2004/09 rev. A