Technology Licensed from International Rectifier APU1160 6A ULTRA LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR DESCRIPTION FEATURES 0.62V Dropout at 6A Fast Transient Response 1% Voltage Reference Initial Accuracy Built-In Thermal Shutdown RoHS Compliant The APU1160 is a 6A regulator with extremely low dropout voltage using a proprietary bipolar process that achieves comparable equivalent on resistance to that of discrete MOSFETs. This product is specifically designed to provide well regulated supply for applications requiring 2.8V or lower voltages from 3.3V ATX power supplies where high efficiency of a switcher can be achieved without the cost and complexity associated with switching regulators. APPLICATIONS VGA Card Applications On-Board Low Voltage Regulator Supply such as 3.3V to 2.8V TYPICAL APPLICATION 3.3V C1 100uF APU1160 VIN 5 VCTRL 4 VOUT 3 Adj VSENSE 2.7V R1 100 1% 2 R2 124 1% 1 5V C3 100uF C2 100uF Figure 1 - Typical application of APU1160 in a 3.3V to 2.8V. PACKAGE ORDER INFORMATION TJ (°C) 5-PIN PLASTIC TO-263 (S) 0 To 125 APU1160S Data and specifications subject to change without notice. 200428061-1/5 APU1160 ABSOLUTE MAXIMUM RATINGS Input Voltage (V IN) .................................................... Control Input Voltage (V CTRL) ..................................... Power Dissipation ..................................................... Storage Temperature Range ...................................... Operating Junction Temperature Range ..................... 7V 14V Internally Limited -65°C To 150°C 0°C To 150°C PACKAGE INFORMATION 5-PIN PLASTIC TO-263 (S) FRONT VIEW Tab is V OUT 5 VIN 4 VCTRL 3 VOUT 2 Adj 1 VSENSE θJA=35°C/W for 0.5" square pad ELECTRICAL SPECIFICATIONS Unless otherwise specified, these specifications apply over CIN=mF, COUT=10mF, and TJ=0 to 1258C. Typical values refer to TJ=258C. VOUT=VSENSE. PARAMETER Reference Voltage SYM VREF TEST CONDITION VCTRL=2.75, VIN=2V, Io=10mA, TJ=258C, V ADJ=0V MIN TYP MAX UNITS 1.225 1.250 1.275 V 1.225 1.250 1.275 VCTRL=2.7 to 12V, VIN=2.05V to 5.5V, Io=10mA to 6A, VADJ=0V Line Regulation Load Regulation (Note 1) Dropout Voltage (Note 2) (V CTRL - VOUT) Dropout Voltage (Note 2) (V IN - VOUT) Current Limit Minimum Load Current (Note 3) Thermal Regulation Ripple Rejection VCTRL=2.5V to 7V, VIN=1.75V to 5.5V, Io=10mA, V ADJ=0V VCTRL=2.75V, VIN=2.1V, Io=10mA to 6A, VADJ=0V VADJ=0V for all conditions below: VIN=2.05V, Io=1.5A VIN=2.05V, Io=5A VIN=2.05V, Io=6A VADJ=0V for all conditions below: VCTRL=2.75V, Io=1.5A VCTRL=2.75V, Io=5A VCTRL=2.75V, Io=6A VCTRL=2.75V, VIN=2.05V, DVo=100mV, V ADJ=0V VCTRL=5V, VIN=3.3V, V ADJ=0V 30ms Pulse VCTRL=5V, VIN=5V, Io=5A, VADJ=0V, TJ=258C, VRIPPLE=1V PP at 120Hz 3 mV 6 mV 1.00 1.10 1.20 V 1.30 0.15 0.40 0.55 0.20 0.52 0.62 5 0.01 10 0.02 6.2 60 70 V A mA %/W dB 2/5 APU1160 PARAMETER Control Pin Current SYM Adjust Pin Current IADJ TEST CONDITION VADJ=0V for all below conditions: VCTRL=2.75V, VIN=2.05V, Io=1.5A VCTRL=2.75V, VIN=2.05V, Io=5A VCTRL=2.75V, VIN=2.05V, Io=6A VCTRL=2.75V, VIN=2.05V, V ADJ=0V Note 1: Low duty cycle pulse testing with Kelvin connections are required in order to maintain accurate data. Note 2: Dropout voltage is defined as the minimum differential between V IN and V OUT required to maintain regulation at VOUT. It is measured when the output voltage drops 1% below its nominal value. MIN TYP 15 50 60 50 MAX UNITS mA 120 mA Note 3: Minimum load current is defined as the minimum current required at the output in order for the output voltage to maintain regulation. Typically the resistor dividers are selected such that it automatically maintains this current. PIN DESCRIPTIONS PIN # PIN SYMBOL 1 VSENSE 2 3 Adj VOUT 4 VCTRL 5 VIN PIN DESCRIPTION This pin is the positive side of the reference which allows remote load sensing to achieve excellent load regulation. A resistor divider from this pin to the VOUT pin and ground sets the output voltage. The output of the regulator. A minimum of 10mF capacitor must be connected from this pin to ground to insure stability. This pin is the supply pin for the internal control circuitry as well as the base drive for the pass transistor. This pin must always be higher than the V OUT pin in order for the device to regulate. (See specifications) The input pin of the regulator. Typically a large storage capacitor is connected from this pin to ground to insure that the input voltage does not sag below the minimum dropout voltage during the load transient response. This pin must always be higher than VOUT in order for the device to regulate. (See specifications) BLOCK DIAGRAM V IN 5 3 VOUT V CTRL 4 1 VSENSE + 1.25V + CURRENT LIMIT THERMAL SHUTDOWN 2 Adj Figure 2 - Simplified block diagram of the APU1160. 3/5 APU1160 APPLICATION INFORMATION Introduction The APU1160 adjustable regulator is a five-terminal device designed specifically to provide extremely low dropout voltages comparable to the PNP type without the disadvantage of the extra power dissipation due to the base current associated with PNP regulators. This is done by bringing out the control pin of the regulator that provides the base current to the power NPN and connecting it to a voltage that is grater than the voltage present at the VIN pin. This flexibility makes the APU1160 ideal for applications where dual inputs are available such as a computer mother board with an ATX style power supply that provides 5V and 3.3V to the board. One such application is the new graphic chip sets that require anywhere from 2.4V to 2.7V supply such as the Intel I740 chip set. The APU1160 can easily be programmed with the addition of two external resistors to any voltages within the range of 1.25 to 5.5 V. Another major requirement of these graphic chips such as the Intel I740 is the need to switch the load current from zero to several amps in tens of nanoseconds at the processor pins, which translates to an approximately 300 to 500ns of current step at the regulator. In addition, the output voltage tolerances are also extremely tight and they include the transient response as part of the specification. The APU1160 is specifically designed to meet the fast current transient needs as well as providing an accurate initial voltage, reducing the overall system cost with the need for fewer number of output capacitors. Another feature of the device is its true remote sensing capability which allows accurate voltage setting at the load rather than at the device. Output Voltage Setting The APU1160 can be programmed to any voltages in the range of 1.25V to 5.5V with the addition of R1 and R2 external resistors according to the following formula: ( VOUT = VREF3 1+ R2 R1 ) +I VIN APU1160 VCTRL VCTRL V SENSE Adj V REF IADJ = 50uA R1 R2 Figure 3 - Typical application of the APU1160 for programming the output voltage. The APU1160 keeps a constant 1.25V between the V SENSE pin and the VADJ pin. By placing a resistor R1 across these two pins and connecting the VSENSE and VOUT pin together, a constant current flows through R1, adding to the IADJ current and into the R2 resistor producing a voltage equal to the (1.25/R1)3R2 + IADJ3R2. This voltage is then added to the 1.25V to set the output voltage. This is summarized in the above equation. Since the minimum load current requirement of the APU1160 is 10mA, R1 is typically selected to be a 121V resistor so that it automatically satisfies this condition. Notice that since the IADJ is typically in the range of 50mA, it adds a small error to the output voltage and should be considered when very precise output voltage setting is required. Load Regulation Since the APU1160 has separate pins for the output (V OUT ) and the sense (V SENSE), it is ideal for providing true remote sensing of the output voltage at the load. This means that the voltage drops due to parasitic resistance such as PCB traces between the regulator and the load are compensated for using remote sensing. Figure 4 shows a typical application of the APU1160 with remote sensing. VI N V IN V OUT APU1160 3R2 ADJ VC T R L Where: VREF = 1.25V Typically IADJ = 50mA Typically R1 & R2 as shown in Figure 3: VOUT V OUT V IN V SENSE V CTRL RL Adj R1 R2 Figure 4 - Schematic showing connection for best load regulation. 4/5 APU1160 Stability The APU1160 requires the use of an output capacitor as part of the frequency compensation in order to make the regulator stable. Typical designs for the microprocessor applications use standard electrolytic capacitors with typical ESR in the range of 50 to 100mV and an output capacitance of 500 to 1000mF. Fortunately as the capacitance increases, the ESR decreases resulting in a fixed RC time constant. The APU1160 takes advantage of this phenomena in making the overall regulator loop stable. For most applications a minimum of 100mF aluminum electrolytic capacitor such as Sanyo, MVGX series, Panasonic FA series as well as the Nichicon PL series insures both stability and good transient response. Thermal Design The APU1160 incorporates an internal thermal shutdown that protects the device when the junction temperature exceeds the allowable maximum junction temperature. Although this device can operate with junction temperatures in the range of 1508C, it is recommended that the selected heat sink be chosen such that during maximum continuous load operation the junction temperature is kept below this number. The example below shows the steps in selecting the proper surface mount package. Assuming, the following conditions: VOUT = 2.8V VIN = 3.3V VCTRL = 5V IOUT = 3A (DC Avg) Calculate the maximum power dissipation using the following equation: ( I60 )3(V - V ) 3 = 13(3.3 - 2.8)+( ) 3(5 - 2.8) = 1.61W 60 PD = IOUT3(V IN - VOUT)+ PD OUT CTRL OUT Using table below select the proper package and the amount of copper board needed. Pkg TO-263 TO-263 TO-263 TO-263 Copper θJA(°C/W) Area 1.4"X1.4" 25 1.0"X1.0" 30 0.7"X0.7" 35 Pad Size 45 Max Pd (TA=25°C) 4.4W 3.7W 3.1W 2.4W Max Pd (TA=45°C) 3.6W 3.0W 2.6W 2.0W Note: Above table is based on the maximum junction temperature of 1358C. 5/5