SPX3940/41/42 1A Low Drop Out Voltage Regulator with Shutdown (PRELIMINARY INFORMATION) FEATURES APPLICATIONS • Output Accuracy 3.3V, @ 1A Output • Very Low Quiescent Current • Low Dropout Voltage • Extremely Tight Load And Line Regulation • Very Low Temperature Coefficient • Current & Thermal Limiting • Error Flag Warns Of Output Dropout • Battery Powered Systems • Cordless Telephones • Radio Control Systems • Portable/Palm Top/Notebook Computers • Portable Consumer Equipment • Portable Instrumentation • Automotive Electronics • SMPS Post-Regulator • Voltage Reference PRODUCT DESCRIPTION The SPX3940/41/42 is a low power voltage regulator. This device is an excellent choice for battery-powered applications such as cordless telephones, radio control systems and portable computers. The SPX3940/41/42 features very low quiescent current (100µA Typ.) and very low dropout voltage. This includes a tight initial tolerance of 1% max and 2% max., and very low output temperature coefficient, making the SPX3940/41/42 useful as a low-power voltage reference. The error flag output feature is used as power-on reset for warning of a low output voltage, due to a falling voltage input of batteries. Another feature is the logic-compatible shutdown input which enables the regulator to be switched on and off. The SPX3940/41/42 is offered in 3-pin and 5-pin TO-220 package SOT-223, and surface mount TO-263 packages. The regulator output voltage (of the 8-pin SO-8 and 5-pin TO-220 & TO-263) may be pin-strapped for a 3.3V or programmed from 1.24V to 29V with an external pair of resistors. PIN CONNECTIONS TO-220-5 Package Five Lead Package Pin Functions: SPX3941 SPX3942 1) ERROR ADJUST 2) INPUT SHUTDOWN 3) GND GND 4) OUTPUT 5) SHUTDOWN INPUT SPX3941/42 1 2 VOUT SPX3940 3 VIN GND/ VOUT GND/ ADJ V IN Front View ADJ Front View TO-252 Package TO-263Package OUTPUT 1 2 3 4 5 Top View SPX3940 Top View TO-220 Package SPX3940 SPX3941/42 1 2 3 4 5 SOT-223 Package 3 2 1 Front View VOUT ADJ/GND VIN SPX3940 TO-263-5 Package 3 VOUT 2 GND/ ADJ 1 V IN Front View Rev. 12/19/00 SPX3940/41/42 ABSOLUTE MAXIMUM RATINGS Power Dissipation..........................................Internally Limited Lead Temp. (Soldering, 5 Seconds) ................................ 260°C Storage Temperature Range .............................. -65° to +150°C Operating Junction Temperature Range (Note 9) SPX3940/41/42...................................... -40C° to +125°C Input Supply Voltage ................................................... +7.5V Feedback Input Voltage ..................................-1.5V to +30V Shutdown Input Voltage..................................-0.3V to +30V Error Comparator Output ................................-0.3V to +30V ESD Rating ............................................................ 2KV Min ELECTRICAL CHARACTERISTICS at VS=±15V,TA=25°C, unless otherwise specified. Boldface applies over the full operating temperature range. PARAMETER CONDITIONS Typ. (Note 2) 3.3V Version Output Voltage -40°C ≤TJ ≤+125°C 3.3 3.3 SPX3940A Min Max 3.267 3.217 3.333 3.382 SPX3940/41 Min Max 3.234 3.185 UNITS 3.366 3.415 V 1mA ≤IL ≤ 1A All Voltage Options Output Voltage Temperature Coefficient Line Regulation ( Note 3) Load Regulation ( Note 3 ) (Note 1) 6V ≤ VIN ≤30V (Note 4) IL = 50mA to 1mA Output Noise Voltage BV = 10Hz – 100kHz Ground Current IL = 5mA 4.5V<Vin<5.5V IL = 5mA 20 100 150 ppm/°C 20 35 40 50 80 60 50 80 mV mV µV(rms) 150 10 Current Limit Vin=5V IL = 1A VOUT = 0 110 1.7 Thermal Regulation Dropout Voltage (Note 5) IL = 1A 0.05 0.5 IL = 100mA 110 Typ 1.235 Adjustable Versions only Reference Voltage Reference Voltage Over Temperature (Note 6) Feedback Pin Bias Current Reference Voltage Temperature Coefficient Feedback Pin Bias Current Temperature Coefficient 20 (Note 7) 15 20 15 20 200 250 200 250 1.2 1.2 0.2 0.8 1.0 150 200 mA A 0.2 0.8 1.0 150 200 SPX3940/42 1.200 1.270 1.98 1.272 1.185 1.285 60 80 %/w V V V nA 50 ppm/°C 0.1 nA/°C Rev. 12/19/00 SPX3940/41/42 (Continued) PARAMETER CONDITIONS Typ. Output Leakage Current V0H = 30V 0.01 Output Low Voltage 150 Upper Threshold Voltage VIN = 4.5V I0L = 400µA (Note 8) Lower Threshold Voltage (Note 8) 75 Hysteresis Input logic Voltage (Note 8) Low (Regulator ON) High (Regulator OFF) VS = 2.4V 15 1.3 30 VS = 30V 450 Shut down Pin Input Current Regulator Output Current in Shutdown SPX3940/42 Min (Note 2) 60 3 UNITS Max 1.00 2.00 250 400 40 25 µA mV mV 95 140 mV mV V 2.0 0.7 90 150 800 1000 15 25 µA µA Note 1: Output or reference voltage temperature coefficients defined as the worst case voltage change divided by the total temperature range. Note 2: Unless otherwise specified all limits are guaranteed for Tj = 25°C, VIN = 6V, IL = 100µA and CL = 1µF. Additional conditions for the 8-pin versions are feedback tied to 5V tap and output tied to output sense (VOUT = 5V) and VSHUTDOWN ≤ 0.8V. Note 3: 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 4: Line regulation for the SPX3940/41/42 is tested at 150°C for IL = 1 mA. For IL = 100µA and TJ = 125°C, line regulation is guaranteed by design to 0.2%. See typical performance characteristics for line regulation versus temperature and load current. 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: VREF ≤VOUT ≤ (Vin - 1V), 2.3 ≤Vin≤30V, 100µA≤IL≤ 250 mA, TJ ≤ TJMAX. Note 7: Comparator thresholds are expressed in terms of a voltage differential at the feedback terminal below the nominal reference voltage measured at 6V input. 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 8: VSHUTDOWN ≥ 2V, VIN ≤ 30V, VOUT =0, Feedback pin tied to 5V Tap. Note 9: The junction -to-ambient thermal resistance of the TO-92 package is 180°C/ W with 0.4” leads and 160°C/ W with 0.25” leads to a PC board. The thermal resistance of the 8-Pin DIP package is 105°C/W junction-to-ambient when soldered directly to a PC board. Junction-to-ambient thermal resistance for the SOIC (S) package is 160°C/W. Rev. 12/19/00 SPX3940/41/42 APPLICATION HINTS EXTERNAL CAPACITORS The stability of the SPX3940/41/42 requires a 2.2µF or greater capacitor between output and ground. Oscillation could occur without this capacitor. Most types of tantalum or aluminum electrolytic works fine here. For operations of below -25°C solid tantalum is recommended since the many aluminum types have electrolytes the freeze at about -30°C. The ESR of about 5Ω or less and resonant frequency above 500kHz are the most important parameters in the value of the capacitor. The capacitor value can be increased without limit. At lower values of output current, less output capacitance is required for stability. For the currents below 10mA the value of the capacitor can be reduced to 0.5µF and 0.15µF for 1A. More output capacitance needed for the 8-pin version at voltages below 5V since it runs the error amplifier at lower gain. At worst case 5µF or greater must be used for the condition of 250mA load at 1.23V output. The SPX3940/41/42, unlike other low dropout regulators will remain stable and in regulation with no load in addition to the internal voltage divider. This feature is especially important in application like CMOS RAM keep-alive. When setting the output voltage of the SPX3940/41/42, a minimum load of 10mA is recommended. 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 then a 0.1µF tantalum or aluminum electrolytic capacitor should be placed from the input to the ground. Instability can occur if there is stray capacitance to the SPX3940/41/42 feedback terminal (pin 7). This could cause more problems when using a higher value of external resistors to set the output voltage. This problem can be fixed by adding a 100pF capacitor between output and feedback and increasing the output capacitor to at least 3.3µF. ERROR DETECTION COMPARATOR OUTPUT The Comparator produces a logic low output whenever the SPX3940/41/42 output falls out of regulation by more than around 5%. This is around 60mV offset divided by the 1.235 reference voltage. This trip level remains 5% below normal regardless of the programmed output voltage of the regulator. Figure 1 shows the timing diagram depicting the ERROR signal and the regulator output voltage as the SPX3940/41/42 input is ramped up and down. The ERROR signal becomes low at around 1.3V input, and goes high around 5V input (input voltage at which Vout = 4.75). Since the SPX3940/41/42’s dropout voltage is load dependent, the input voltage trip point (around 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 pull-up resistor. Depending on the system requirements the resistor may be returned to 5V output or other supply voltage. In determining the value of this resistor, note that the output is rated to sink 400µA, this value adds to battery drain in a low battery condition. Suggested values range from 100K to 1MΩ. If the output is unused this resistor is not required. PROGRAMMING THE OUTPUT VOLTAGE OF SPX3940/41/42 The SPX3940/41/42 may be pin-strapped for 5V using its internal voltage divider by tying Pin 1 (output) to Pin 2 (sense) and Pin 7 (feedback) to Pin 6 (5V Tap). 4 .7 5 V O U T PU T V OL TA GE _______ ERRO R* +5 .0 V IN P U T V OL TA GE +1 .3 V + + * S e e A p p lica tio n In fo . _______ F ig u r e 1 . E R R O R O u tp u t T im in g Rev. 12/19/00 SPX3940/41/42 Also, 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. Refer to the below equation for the programming of the output voltage:: VOUT = VREF × ( 1 + R1\ R2 )+ IFBR1 The VREF is 1.235 and IFB is the feedback bias current, nominally -20nA. The minimum recommended load current of 1 µA forces an upper limit of 1.2 MΩ on value of R2. If no load is presented the IFB produces an error of typically 2% in VOUT, which may be eliminated at room temperature by trimming R1. To improve the accuracy choose the value of R2 = 100k this reduces the error by 0.17% and increases the resistor program current by 12µA. Since the LP2951 typically draws 60 µA at no load with Pin 2 opencircuited this is a small price to pay REDUCING OUTPUT NOISE It may be an advantage to reduce the AC noise present at the output. One way 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 SPX3940/41/42 but is relatively inefficient, as increasing the capacitor from 1µF to 220µF only decreases the noise from 430µV to 160µV Vrms for a 100kHz 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 / 2πR1 × 200 Hz or choose 0.01µF. When doing this, the output capacitor must be increased to 3.3µF to maintain stability. These changes reduce the output noise from 430µV to 100µV Vrms for a 100kHz 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. HEAT SINK REQUIREMENTS Depending on the maximum ambient temperature and maximum power dissipation a heat sink may be required with the SPX3940/41/42. The junction temperature range has to be within the range specified under Absolute Maximum Ratings under all possible operating conditions. To find out if a heat sink is required, the maximum power dissipation of the device needs to be calculated. This is the maximum specific AC voltage that must be taken into consideration at input. Figure 3 shows the condition and power dissipation which should be calculated with the following formula: VIN IIN 3.3V IN PTOTAL = (VIN - 5) IL + (VIN)IG Junction to ambient thermal resistance θ(j-A) can be calculated after determining of PTOTAL & TR (max): IL SPX3940 Next step is to calculate the temperature rise TR (max). TJ (max) maximum allowable junction temperature, TA (max) maximum ambient temperature : TR (max) = TJ (max) - TA (max) OUT GND IIN = IL + IG LOAD + + 2.2 uF IG Figure 3. 3.3V Regulator Circuit θ(J-A) = TR (max)/P(max) If the θ(J-A) is 60°C/W or higher, the device could be operated without a heat sink. If the value is below 60°C/W then the heat sink is required and the thermal resistance of the heat sink can be calculated by the following formula, θ(J-C) junction to case, θ(C-H) case to heat sink, θ(H-A) heat sink to ambient: θ(J-A) = θ(J-C) + θ(C-H) + θ(H-A) Rev. 12/19/00 SPX3940/41/42 TYPICAL APPLICATIONS +VIN +VIN *V VOUT OUT = 3.3V SPX3940 + 10uF GND 4 SPX3940 FIXED +3.3V REGULATOR Rev. 12/19/00 SPX3940/41/42 ORDERING INFORMATION Ordering No. SPX3940AM3 SPX3940AM3-3.3 SPX3940AM3-5.0 SPX3940M3 SPX3940M3-3.3 SPX3940M3-5.0 SPX3940AR SPX3940AR-3.3 SPX3940AR-5.0 SPX3940R SPX3940R-3.3 SPX3940R-5.0 SPX3940AU SPX3940AU-3.3 SPX3940AU-5.0 SPX3940U SPX3940U-3.3 SPX3940U-5.0 SPX3940AT SPX5940AT-3.3 SPX3940AT-5.0 SPX3940T SPX3940T-3.3 SPX3940T-5.0 SPX3941R-3.3 SPX3941R-5.0 SPX3941U-3.3 SPX3941U-5.0 SPX3941T-3.3 SPX3941T-5.0 SPX3942R SPX3942U SPX3942T Precision Output Voltage 1% 1% 1% 2% 2% 2% 1% 1% 1% 2% 2% 2% 1% 1% 1% 2% 2% 2% 1% 1% 1% 2% 2% 2% 2% 2% 2% 2% 2% 2% 2% 2% 2% Adj 3.3V 5.0V Adj 3.3V 5.0V Adj 3.3V 5.0V Adj 3.3V 5.0V Adj 3.3V 5.0V Adj 3.3V 5.0V Adj 3.3V 5.0V Adj 3.3V 5.0V 3.3V 5.0V 3.3V 5.0V 3.3V 5.0V Adj Adj Adj Packages 3 Lead SOT-223 3 Lead SOT-223 3 Lead SOT-223 3 Lead SOT-223 3 Lead SOT-223 3 Lead SOT-223 5 Lead TO-252 3 Lead TO-252 3 Lead TO-252 5 Lead TO-252 3 Lead TO-252 3 Lead TO-252 5 Lead TO-220 3 Lead TO-220 3 Lead TO-220 5 Lead TO-220 3 Lead TO-220 3 Lead TO-220 5 Lead TO-263 3 Lead TO-263 3 Lead TO-263 5 Lead TO-263 3 Lead TO-263 3 Lead TO-263 3 Lead TO-252 3 Lead TO-252 3 Lead TO-220 3 Lead TO-220 3 Lead TO-263 3 Lead TO-263 5 Lead TO-252 3 Lead TO-220 3 Lead TO-263 Corporation SIGNAL PROCESSING EXCELLENCE Sipex Corporation Headquarters and Main Offices: 22 Linnell Circle Billerica, MA 01821 TEL: (978) 667-8700 FAX: (978) 670-9001 e-mail: [email protected] 233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 935-7600 FAX: (408) 934-7500 Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described hereing; neither does it convey any license under its patent rights nor the rights of others. Rev. 12/19/00