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. 350mV dropout @ 3A Adjustable output from 1.2V to 4.8V 2.5V and 1.8V options (5 pin parts also adjustable 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. Typical Application Circuits(1)(2) 1 VIN 2 ENABLE U1 SC1566I5T-2.5 VIN VO EN GND ADJ 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 Battery powered systems Motherboards and notebook computers Peripheral cards Network cards Set top boxes Medical equipment 5 VO = See equation below 4 R1 3 VO = C1 C2 1.200 (R1+ R2) Volts R2 R2 1 VIN 2 ENABLE U1 SC1566I5T-2.5 VIN VO EN GND C1 VO = 2.5V 4 C2 3 1 VIN ADJ 5 U1 SC1566IT-1.8 VIN VO 3 VO = 1.8V GND C1 Revision: April 27, 2005 C2 2 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 Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not implied. Parameter Symbol Max Units Input Voltage VIN 7 V Power Dissipation PD Internally Limited W Thermal Resistance Junction to Ambient TO-263-X TO-220-X θJ A 60 50 °C/W Thermal Resistance Junction to Case TO-263-X TO-220-X θJ C 3 3 °C/W Operating Ambient Temperature Range TA -40 to +85 °C Operating Junction Temperature Range TJ -40 to +150 °C Storage Temperature Range TSTG -65 to +150 °C Lead Temperature (Soldering) 10 Sec. TLEAD 300 °C ESD Rating (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 Symbol Test Conditions Min Typ Max Units 5.5 V VIN Supply Voltage Range VIN Quiescent Current 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 Fixed Voltage) +2% Line Regulation(1) REG(LINE) VIN = (VO + 0.25V) to 5.5V, IOUT = 10mA 0.035 0.3 % Load Regulation(1) REG(LOAD) VIN = VO + 0.7V 0.2 0.4 % VD IO = 10mA 1 5 mV Dropout Voltage(1)(2) 10 IO = 500mA 75 100 mV 150 2005 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 Symbol Test Conditions Min Typ Max Units 200 300 mV VO (Cont.) IO = 1.5A Dropout Voltage(1)(2) 400 IO = 3A 350 450 mV 600 Minimum Load Current(3) IO Current Limit ICL VIN = VO + 0.7V 1 10 µA 3.0 4.5 6.5 A 1.188 1.200 1.212 V ADJ Reference Voltage(1) VREF VIN = 2.2V, VADJ = VOUT, IO = 10mA 1.176 Adjust Pin Current(4) Adjust Pin Threshold(5) IADJ VADJ = VREF VTH(ADJ) 0.10 1.224 10 200 nA 0.20 0.40 V 1.5 10 µA EN Enable Pin Current IEN VEN = 0V, VIN = 3.3V Enable Pin Threshold VIH VIN = 3.3V VIL VIN = 3.3V 1.8 V 0.4 Over Temperature Protection High Trip level Hysteresis 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. 2005 Semtech Corp. 3 www.semtech.com SC1566 POWER MANAGEMENT Pin Configurations Ordering Information Device(1) SC1566 5-PIN Versions SC1566IM-X.X.TR Pin Function SC1566IM-X.XTRT(6) 1 VIN SC1566I5M-X.X.TR(2) 2 EN SC1566I5MX.XTRT(2)(6) 3 GND SC1566IT-X.X 4 AD J SC1566IT-X.XT(6) 5 VO SC1566I5T-X.X(2)(5) TO-263-5 SC1566I5TX.XT(2)(5)(6) TAB IS GND SC1566I5T-X.XSB(2)(5) TO-220-5 SC1566I5TX.XSBT(2)(5)(6) SC1566 3-PIN Versions Pin Function 1 VIN 2 GND 3 VO TO-263-3 TO-263-3(3) TO-263-5(3) TO-220-3(4) TO-220-5(4) TO-220-5(4) 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. (4) Only available in tube packaging. A tube contains 50 devices. (5) T-XX = Straight in-line; T-XX-SB = Single Bend. (6) Lead free product. This product is fully WEEE and RoHS compliant. TAB IS GND Note: (1) 3-pin versions are fixed output voltage only. P ackag e TO-220-3 Pin Descriptions Pin Name Pin Desciption 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 resistors are used, the output voltage will be (See Application Circuits on page 1): VO EN GND = 1.200 (R1 + R2) R2 Volts Enable Input. Pulling this pin below 0.4V turns the regulator off, reducing the quiescent current to a fraction of its operating value. The device will be enabled if this pin is left open. Connect to VIN if not being used. Reference ground. Use the tab (electrically connected to GND) for heatsinking. VIN Input voltage. For regulation at full load, the input to this pin must be between (VO + 0.7V) and 5.5V. Minimum VIN = 2.2V. VO This pin is the power output of the device. 2005 Semtech Corp. 4 www.semtech.com SC1566 POWER MANAGEMENT Block Diagram * 5 lead versions only 2005 Semtech Corp. 5 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 2.550 VIN = 3.2V 2.540 2.540 2.530 2.530 2.520 2.520 2.510 IO = 10mA 2.500 2.490 125 150 IO = 3A 125 150 125 150 VIN = 5.5V 2.510 IO = 10mA 2.500 2.490 2.480 2.480 2.470 2.470 2.460 2.460 2.450 IO = 3A 2.450 -50 -25 0 25 50 75 100 125 150 -50 -25 0 25 TJ (°C) 1.225 1.220 Temperature vs. Output Current Temperature vs. Output Current 1.225 1.220 1.215 1.210 1.210 IO = 10mA 1.200 IO = 3A 1.190 100 Reference Voltage vs. Junction 1.215 1.195 75 Reference Voltage vs. Junction VIN = 2.2V 1.205 50 TJ (°C) VREF (V) VREF (V) 75 Output Voltage (2.5V) vs. Junction VO (V) VO (V) 2.550 50 TJ (°C) VIN = 5.5V 1.205 IO = 3A 1.200 1.195 IO = 10mA 1.190 1.185 1.185 1.180 1.180 1.175 1.175 -50 -25 0 25 50 75 100 125 150 -50 TJ (°C) 2005 Semtech Corp. -25 0 25 50 75 100 TJ (°C) 6 www.semtech.com SC1566 POWER MANAGEMENT Typical Characteristics (Cont.) 700 690 Quiescent Current vs. Off-State Quiescent Current vs. Junction Temperature Junction Temperature 12 VIN = 3.3V 10 680 670 8 660 IQ(OFF) (µA) IQ (µA) VIN = 5.5V 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 to choose an appropriate output capacitor for a given stability requirement. 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). Noise immunity: in very electrically noisy environments, it is recommended that 0.1µF ceramic capacitors be placed from IN to GND and OUT to GND as close to the device pins as possible. External voltage selection resistors (5-pin parts): the use of 1% resistors, and designing for a current flow ≥ 10µµA is recommended to ensure a well regulated output (thus R2 ≤ 120kΩ). Component Selection 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. 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: PD ≈ (VIN − VOUT ) • I O Output capacitor: a minimum bulk capacitance of 2.2µF, 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. For reference, the phase-margin contour of Figure 1. can be used 2005 Semtech Corp. The absolute worst-case dissipation is given by: PD ( MAX ) = (VIN ( MAX ) − VOUT ( MIN ) )• I O ( MAX ) + VIN ( MAX ) • I Q ( MAX ) For a typical scenario, VIN = 3.3V ± 5%, VOUT = 2.8V and IO = 2.5A, therefore: VIN(MAX) = 3.465V, VOUT(MIN) = 2.744V and IQ(MAX) = 1.75mA, Thus PD(MAX) = 1.81W. 7 www.semtech.com SC1566 POWER MANAGEMENT Applications Information (Cont.) 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): 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 Co=22uF, Stable Region: Unstable Region: Co=2.2uF, Stable Region: Unstable Region: 3mA 3mA 30mA 30mA Load Load 300mA 300mA 0.001 0.01 0.1 3A 10 1 0.001 0.01 0.1 1 3A 10 ESR(Ohms) ESR(Ohms) Co=220uF, Stable Region: Unstable Region: 3mA 30mA Load 300mA 0.001 0.01 0.1 1 3A 10 ESR(Ohms) Figure 1. Phase-margin Contour Plot 2005 Semtech Corp. 8 www.semtech.com SC1566 POWER MANAGEMENT Outline Drawing - T0-263-3 Minimum Land Pattern - TO-263-3 2005 Semtech Corp. 9 www.semtech.com SC1566 POWER MANAGEMENT Outline Drawing - TO-263-5 Minimum Land Pattern - TO-263-5 2005 Semtech Corp. 10 www.semtech.com SC1566 POWER MANAGEMENT Outline Drawing - TO-220-3 Outline Drawing - TO-220-5 2005 Semtech Corp. 11 www.semtech.com SC1566 POWER MANAGEMENT Outline Drawing - TO-220-5 (T-XX-SB Option) Contact Information Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805)498-2111 FAX (805)498-3804 2005 Semtech Corp. 12 www.semtech.com