SC1566 Very Low Dropout 3.0 Amp Regulator With Enable POWER MANAGEMENT Description Features The SC1566 is a high performance positive voltage regulator designed for use in applications requiring very low dropout voltage at up to 3 Amps. Since it has superior dropout characteristics compared to regular LDOs, it can be used to supply 2.5V on motherboards or 2.8V on peripheral cards from the 3.3V supply thus allowing heat sink size reduction or elimination. Additionally, the five pin versions of SC1566 have an enable pin, to further reduce power dissipation while shut down. The SC1566 provides excellent regulation over variations in line, load and temperature. u 350mV dropout @ 3A u Adjustable output from 1.2V to 4.8V u 2.5V and 1.8V options (5 pin parts also adjustable u u u u u u externally using resistors) Over current and over temperature protection Enable pin 10µA quiescent current in shutdown Low reverse leakage (output to input) Full industrial temperature range TO-220 and TO-263 packages Applications The SC1566 is available as three terminal fixed output voltage and five terminal fixed or adjustable output voltage devices with enable. Two package options are available: TO-263 and TO-220. u u u u u u Typical Application Circuits(1)(2) Battery powered systems Motherboards and notebook computers Peripheral cards Network cards Set top boxes Medical equipment U1 SC1566I5T-2.5 1 VIN 2 ENABLE VIN VO EN GND ADJ 5 VO = See equation below 4 R1 3 VO = C1 C2 1.200 (R1+ R2) Volts R2 R2 U1 SC1566I5T-2.5 1 VIN 2 ENABLE VIN VO EN GND C1 ADJ 5 VO = 2.5V 4 C2 3 U1 SC1566IT-1.8 1 VIN VIN VO 3 VO = 1.8V GND C1 C2 2 Revision 1, January 2001 1 Notes: (1) Maximum VO setpoint for 1.8V parts = 5.4V (2) This device is designed to operate with ceramic input and output capacitors www.semtech.com SC1566 POWER MANAGEMENT Absolute Maximum Ratings Parameter Sy mbol Max U nits Input Voltage VIN 5.5 V Power D i ssi pati on PD Internally Li mi ted W Thermal Resi stance Juncti on to Ambi ent SC 1566IM (TO-263) SC 1566IT (TO-220) q JA 60 50 °C /W Thermal Resi stance Juncti on to C ase SC 1566IM (TO-263) SC 1566IT (TO-220) q JC 3 3 °C /W Operati ng Ambi ent Temperature Range TA -40 to +85 °C Operati ng Juncti on Temperature Range TJ -40 to +150 °C Storage Temperature Range TSTG -65 to +150 °C Lead Temperature (Solderi ng) 10 Sec. TLEAD 300 °C ESD Rati ng (Human Body Model) V ESD 2 kV Electrical Characteristics Unless specified: VEN = VIN. Adjustable Option (VADJ > VTH(ADJ)): VIN = 2.2V to 5.5V and IO = 10µA to 3A. Fixed Options (VADJ = GND): VIN = (VO + 0.7V) to 5.5V and IO = 0A to 3A. Values in bold apply over the full operating temperature range. Parameter Sy mbol Test C onditions Min Ty p Max U nits 5.5 V VIN Supply Voltage Range VIN Qui escent C urrent IQ 2.2 VIN = 3.3V 0.75 1.75 mA VIN = 5.5V, VEN = 0V 10 35 µA VO +1% V VO Output Voltage(1) VO VIN = VO + 0.7V, IO = 10mA -1% -2% (Internal Fi xed Voltage) +2% Li ne Regulati on(1) REG(LINE) VIN = (VO + 0.25V) to 5.5V, IOUT = 10mA 0.035 0.3 % Load Regulati on(1) REG(LOAD) VIN = VO + 0.7V 0.2 0.4 % VD IO = 10mA 1 5 mV D ropout Voltage(1)(2) 10 IO = 500mA 75 100 mV 150 ã 2001 Semtech Corp. 2 www.semtech.com SC1566 POWER MANAGEMENT Electrical Characteristics (Cont.) Unless specified: VEN = VIN. Adjustable Option (VADJ > VTH(ADJ)): VIN = 2.2V to 5.5V and IO = 10µA to 3A. Fixed Options (VADJ = GND): VIN = (VO + 0.7V) to 5.5V and IO = 0A to 3A. Values in bold apply over the full operating temperature range. Parameter Sy mbol Test C onditions Min Ty p Max U nits 200 300 mV VO (C ont.) IO = 1.5A D ropout Voltage(1)(2) 400 IO = 3A 350 450 mV 600 Mi ni mum Load C urrent(3) IO C urrent Li mi t ICL VIN = VO + 0.7V 1 10 µA 3.0 4.5 6.5 A 1.188 1.200 1.212 V AD J Reference Voltage(1) VREF VIN = 2.2V, VADJ = VOUT, IO = 10mA 1.176 Adjust Pi n C urrent(4) Adjust Pi n Threshold(5) IADJ VADJ = VREF VTH(ADJ) 0.10 1.224 10 50 nA 0.20 0.40 V 1.5 10 µA EN Enable Pi n C urrent IEN VEN = 0V, VIN = 3.3V Enable Pi n Threshold VIH VIN = 3.3V VIL VIN = 3.3V 1.8 V 0.4 Ov er Temperature Protection Hi gh Tri p level Hysteresi s THI 175 °C THYST 10 °C Notes: (1) Low duty cycle pulse testing with Kelvin connections required. (2) Defined as the input to output differential at which the output voltage drops to 1% below the value measured at a differential of 0.7V. (3) Required to maintain regulation. Voltage set resistors R1 and R2 are usually utilized to meet this requirement. Adjustable versions only. (4) Guaranteed by design. (5) When VADJ exceeds this threshold, the Sense Select switch disconnects the internal feedback chain from the error amplifier and connects VADJ instead. ã 2001 Semtech Corp. 3 www.semtech.com SC1566 POWER MANAGEMENT Pin Configurations Ordering Information SC 1566 5-PIN Versions D ev ice(1) P ackag e SC 1566IM-X.X.TR TO-263-3(3) Pin Function SC 1566I5M-X.X.TR(2) TO-263-5(3) 1 VIN SC 1566IT-X.X TO-220-3(4) 2 EN SC 1566I5T-X.X(2) TO-220-5(4) 3 GND 4 AD J 5 VO TO-263-5 Notes: (1) Where -X.X denotes voltage options. Available voltages are: 2.5V and 1.8V. (2) Output voltage can be adjusted using external resistors, see Pin Descriptions below. (3) Only available in tape and reel packaging. A reel contains 800 devices. (6) Only available in tube packaging. A tube contains 50 devices. TAB IS GND TO-220-5 SC 1566 3-PIN Versions Pin Function 1 VIN 2 GND 3 VO TO-263-3 Block Diagram TAB IS GND Note: (1) 3-pin versions are fixed output voltage only. TO-220-3 * 5 lead versions only Pin Descriptions Pin N ame Pin D esciption AD J Thi s pi n, when grounded, sets the output voltage to that set by the i nternal feedback resi stors. If external feedback resi stors are used, the output voltage wi ll be (See Appli cati on C i rcui ts on page 1): VO EN GND = 1.200 (R1 + R2) R2 Volts Enable Input. Pulli ng thi s pi n below 0.4V turns the regulator off, reduci ng the qui escent current to a fracti on of i ts operati ng value. The devi ce wi ll be enabled i f thi s pi n i s left open. C onnect to VIN i f not bei ng used. Reference ground. Use the tab (electri cally connected to GND ) for heatsi nki ng. VIN Input voltage. For regulati on at full load, the i nput to thi s pi n must be between (VO + 0.7V) and 5.5V. Mi ni mum VIN = 2.2V. VO Thi s pi n i s the power output of the devi ce. ã 2001 Semtech Corp. 4 www.semtech.com SC1566 POWER MANAGEMENT Typical Characteristics Dropout Voltage vs. Output Current Dropout Voltage vs. Junction vs. Junction Temperature Temperature vs. Output Current 500 500 150°C 450 450 400 350 350 0°C -40°C 300 VD (mV) VD (mV) IO = 3A 400 25°C 250 200 250 200 150 150 100 100 50 50 0 IO = 1.5A 300 IO = 0.5A 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 -50 -25 0 25 IO (A) 100 Output Voltage (2.5V) vs. Junction Temperature vs. Output Current Temperature vs. Output Current 150 125 150 125 150 VIN = 5.5V 2.540 2.530 2.530 2.520 2.520 2.510 125 2.550 VIN = 3.2V 2.540 IO = 10mA 2.500 2.490 2.510 IO = 10mA 2.500 2.490 IO = 3A IO = 3A 2.480 2.480 2.470 2.470 2.460 2.460 2.450 2.450 -50 -25 0 25 50 75 100 125 150 -50 -25 0 25 TJ (°C) 50 75 100 TJ (°C) Reference Voltage vs. Junction Reference Voltage vs. Junction Temperature vs. Output Current Temperature vs. Output Current 1.225 1.225 VIN = 2.2V VIN = 5.5V 1.220 1.220 1.215 1.215 1.210 1.210 1.205 VREF (V) VREF (V) 75 Output Voltage (2.5V) vs. Junction VO (V) VO (V) 2.550 50 TJ (°C) IO = 10mA 1.200 1.195 IO = 3A 1.205 1.195 1.190 1.190 1.185 1.185 1.180 1.180 1.175 IO = 3A 1.200 IO = 10mA 1.175 -50 -25 0 25 50 75 100 125 150 -50 TJ (°C) ã 2001 Semtech Corp. -25 0 25 50 75 100 TJ (°C) 5 www.semtech.com SC1566 POWER MANAGEMENT Typical Characteristics (Cont.) Quiescent Current vs. Off-State Quiescent Current vs. Junction Temperature Junction Temperature 12 700 VIN = 5.5V VIN = 3.3V 690 10 680 8 IQ(OFF) (µA) IQ (µA) 670 660 650 640 6 4 630 620 2 610 600 0 -50 -25 0 25 50 75 100 125 -50 150 -25 0 25 50 75 100 125 150 TJ (°C) TJ (°C) Applications Information Introduction External voltage selection resistors (5-pin parts): the use of 1% resistors, and designing for a current flow ³ 10µA is recommended to ensure a well regulated output (thus R2 £ 120kW). The SC1566 is intended for applications such as graphics cards where high current capability and very low dropout voltage are required. It provides a very simple, low cost solution that uses very little pcb real estate and typically does not require a heatsink. Additional features include an enable pin to allow for a very low power consumption standby mode, and a fully adjustable output (5-pin versions). Thermal Considerations The power dissipation in the SC1566 is approximately equal to the product of the output current and the input to output voltage differential: Component Selection PD ≈ (VIN − VOUT ) • I O Input capacitor: a 4.7µF or 10µF ceramic capacitor is recommended. This allows for the device being some distance from any bulk capacitance on the rail. Additionally, input droop due to load transients is reduced, improving load transient response. Additional capacitance may be added if required by the application. The absolute worst-case dissipation is given by: PD ( MAX ) = (VIN ( MAX ) − VOUT )• I O ( MAX ) + VIN ( MAX ) • I Q ( MAX ) For a typical scenario, VIN = 3.3V ± 5%, VOUT = 2.8V and IO = 2.5A, therefore: Output capacitor: a minimum bulk capacitance of 22µF, along with a 0.1µF ceramic decoupling capacitor is recommended. Increasing the bulk capacitance will improve the overall transient response. The use of multiple lower value ceramic capacitors in parallel to achieve the desired bulk capacitance will not cause stability issues. Although designed for use with ceramic output capacitors, the SC1566 is extremely tolerant of output capacitor ESR values and thus will also work comfortably with tantalum output capacitors. ã 2001 Semtech Corp. ( MIN ) VIN(MAX) = 3.465V, VOUT(MIN) = 2.744V and IQ(MAX) = 1.75mA, Thus PD(MAX) = 1.81W. Using this figure, and assuming TA(MAX) = 85°C, we can calculate the maximum thermal impedance allowable to maintain TJ £ 150°C (see page 7): 6 www.semtech.com SC1566 POWER MANAGEMENT Applications Information (Cont.) R TH ( J − A )( MAX ) (T = J( MAX ) − TA (MAX ) ) PD (MAX ) This should be achievable for the TO-263 package using pcb copper area to aid in conducting the heat away from the device, such as a large (~2 squ. inch) pad connected to the tab of the device. Internal ground/power planes and air flow will also assist in removing heat. For higher power dissipations it may be necessary to use a small heatsink and the TO-220 package. (150 − 85 ) = 36 °C / W = 1 .81 R TH ( J − C )( MAX ) = 3 °C / W and R TH ( C − S ) = 0 °C / W , therefore R TH ( S − A )( MAX ) = 33 °C / W Outline Drawing - T0-263-3 Minimum Land Pattern - TO-263-3 ã 2001 Semtech Corp. 7 www.semtech.com SC1566 POWER MANAGEMENT Outline Drawing - TO-263-5 Minimum Land Pattern - TO-263-5 ã 2001 Semtech Corp. 8 www.semtech.com SC1566 POWER MANAGEMENT Outline Drawing - TO-220-3 Outline Drawing - TO-220-5 Contact Information Semtech Corporation Power Management Products Division 652 Mitchell Rd., Newbury Park, CA 91320 Phone: (805)498-2111 FAX (805)498-3804 ã 2001 Semtech Corp. 9 www.semtech.com