SC553 150mA Ultra Low Dropout Regulator with Adjustable Output POWER MANAGEMENT Description Features The SC553 is a low dropout linear regulator that operates from a +2.25V to +6.5V input range and delivers up to 150mA. A PMOS pass transistor allows the low 75µA supply current to remain independent of load, making these devices ideal for battery operated portable equipment such as cellular phones, cordless phones and personal digital assistants. ! “5205” compatible pinout ! 2% output accuracy guaranteed over line, load and ! ! ! ! ! ! ! ! ! The SC553 has an adjust pin (ADJ) enabling the user to set the output voltage anywhere from 1.25V to 6V. For a low noise version, see SC1453 and for an error flag see SC1457. Other features include low powered shutdown, short circuit protection, thermal shutdown protection and reverse battery protection. The SC553 comes in the tiny 5 lead SOT-23 package. temperature Guaranteed 150 mA output current Very small external components - designed to work with ceramic capacitors Output adjustable from 1.25V to 6V Very low supply current Thermal overload protection Reverse battery protection Low power shutdown Full industrial temperature range Surface mount packaging (5 pin SOT-23) Applications ! ! ! ! ! ! ! Battery Powered Systems Cellular Telephones Cordless Telephones Personal Digital Assistants Portable Instrumentation Modems PCMCIA cards Typical Application Circuit 1 VIN C1 1uF 3 U1 SC553 IN OUT EN GND ADJ 5 4 VOUT R1 C2 1uF R1 VOUT = 1.250 • 1 + R2 2 R2 Revision: April 20, 2004 1 www.semtech.com SC553 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 Maximum Units Input Supply Voltage VIN -0.6 to +7 V Enable Voltage V EN -0.6 to VIN V Output Pin Voltage VOUT -0.6 to +7 V Adjust Pin Voltage V AD J -0.6 to +7 V Thermal Resistance Junction to Ambient θJ A 256 °C/W Thermal Resistance Junction to Case θJ C 81 °C/W Operating Ambient Temperature Range TA -40 to +85 °C Operating Junction Temperature Range TJ -40 to +125 °C Storage Temperature Range TSTG -65 to 150 °C Lead Temperature (Soldering) 10 Sec. TLEAD 300 °C Electrical Characteristics Unless specified: VIN = 2.25V, VEN = VIN, IOUT = 100µA, CIN = COUT = 1µF, TA = 25°C. Values in bold apply over full operating ambient temperature range. Parameter Symbol Conditions Min Typ Max Units 6.50 V 130 µA IN Supply Voltage Range VIN Supply Current IQ 2.25 IOUT = 0mA to150mA, 2.25V ≤ VIN ≤ 6.5V 75 160 Off-State Supply Current IQ(OFF) VIN = 6.5V, VEN = 0V 0.1 1.0 µA 1.5 ADJ Adjust Pin Voltage (1) Adjust Pin Input Current (2) V AD J IADJ IOUT = 1mA -1.5% 0mA ≤ IOUT ≤ 150mA, 2.25V ≤ VIN ≤ 5.5V -2.0% VADJ = 1.3V 1.250 +1.5% V +2.0% 0.015 2.500 nA 5.000 OUT Line Regulation (1) REG(LINE) VIN = 2.25V to 5.5V, IOUT = 1mA, VADJ = VOUT 1.5 10 mV 12 Load Regulation (1) REG(LOAD) IOUT = 0.1mA to 150mA, VIN = 2.25V, VADJ = VOUT 2004 Semtech Corp. 2 -1 -10 mV -20 www.semtech.com SC553 POWER MANAGEMENT Electrical Characteristics (Cont.) Unless specified: VIN = 2.25V, VEN = VIN, IOUT = 100µA, CIN = COUT = 1µF, TA = 25°C. Values in bold apply over full operating ambient temperature range. Parameter Symbol Conditions Min Typ Max Units OUT (Cont.) Current Limit ILIM Dropout Voltage(1)(3) VD 400 mA IOUT = 1mA 1 IOUT = 50mA 50 mV 65 mV 75 IOUT = 100mA 100 125 mV 155 IOUT = 150mA 150 190 mV 230 EN Enable Input Threshold Enable Input Bias Current (2) VIH 2.25V ≤ VIN ≤ 6.5V VIL 2.25V ≤ VIN ≤ 6.5V IEN 0V ≤ VEN ≤ VIN 1.6 V 0.4 -0.5 0 +0.5 µA Over Temperature Protection High Trip Level Hysteresis THI 150 °C THYST 15 °C Notes: (1) Low duty cycle pulse testing with Kelvin connections required. (2) Guaranteed by design. (3) VOUT = 3.3V. Defined as the input to output differential at which the output voltage drops 100mV below the value measured at a differential of 1V. Not measurable on outputs set below 2.25V due to minimum VIN constraints. See Typical Characteristics for typical dropout voltage at other output voltage settings. 2004 Semtech Corp. 3 www.semtech.com SC553 POWER MANAGEMENT Pin Configuration Ordering Information Top View Part Number (1) P ackag e SC553ISKTR SOT-23-5 SC553ISKTRT(2) Notes: (1) Only available in tape and reel packaging. A reel contains 3000 devices. (2) Lead free product. This product is fully WEEE and RoHS compliant. SOT-23-5L Pin Descriptions Pin # Pin Name Pin Function 1 IN 2 GND 3 EN Active high enable pin. Connect to IN if not being used. 4 AD J Adjust pin. Connecting this pin to an external resistor divider (see Typical Application Circuit on page 1) sets VOUT to: R1 VOUT = 1.250 • 1 + R 2 5 OUT Regulator output, sourcing up to 150mA. Input pin. Ground pin. Can be used for heatsinking if needed. Block Diagram 2004 Semtech Corp. 4 www.semtech.com SC553 POWER MANAGEMENT Marking Information Top Mark Bottom Mark 553 yyww yyww = Datecode (Example: 0108) Applications Information Theory Of Operation Component Selection - General The SC553 is intended for applications where very low dropout voltage, low supply current and low output noise are critical. It provides a very simple, low cost solution that uses very little pcb real estate. Only two external capacitors are required for operation. Output capacitor - Semtech recommends a minimum capacitance of 1µF at the output with an equivalent series resistance (ESR) of < 1Ω over temperature. While the SC553 has been designed to be used with ceramic capacitors, it does not have to be used with ceramic capacitors, allowing the designer a choice. Increasing the bulk capacitance will further reduce output noise and improve the overall transient response. The SC553 contains a bandgap reference trimmed for optimal temperature coefficient which is fed into the inverting input of an error amplifier. The output voltage of the regulator is divided down externally using a resistor divider and compared to the bandgap voltage via the adjust pin (ADJ). The error amplifier drives the gate of a low RDS(ON) P-channel MOSFET pass device to maintain VOUT such that VADJ = VREF. Input capacitor - Semtech recommends the use of a 1µF ceramic capacitor at the input. 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 overall load transient response. External voltage selection resistors - the use of 1% resistors, and designing for a current flow ≥ 10µA is recommended to ensure a well regulated output (thus R2 ≤ 125kΩ). The output voltage (referring to Figure 1 below) will be: An active high enable pin (EN) allows the regulator to be shut down. Pulling this pin low causes the device to enter a very low power shutdown mode, where it will draw typically 0.1µA from the input supply. The regulator has its own current limit circuitry to ensure that the output current will not damage the device during output short, overload or start-up. The current limit is guaranteed to be greater than 400mA to allow fast charging of the output capacitor and high initial currents for DSP initialization. R1 VOUT = 1.250 • 1 + R 2 1 VIN The SC553 includes thermal shutdown circuitry to turn off the device if T J exceeds 150°C (typical), with the device remaining off until TJ drops by 15°C (typical). Reverse battery protection circuitry ensures that the device cannot be damaged if the input supply is accidentally reversed, limiting the reverse current to less than 1.5mA. 2004 Semtech Corp. C1 1uF 3 U1 SC553 IN OUT EN GND ADJ 5 4 VOUT R1 C2 1uF 2 R2 Figure 1 5 www.semtech.com SC553 POWER MANAGEMENT Applications Information (Cont.) Thermal Considerations Layout Considerations The worst-case power dissipation for this part is given by: While layout for linear devices is generally not as critical as for a switching application, careful attention to detail will ensure reliable operation. PD(MAX ) = (VIN(MAX) − VOUT(MIN) ) • IOUT(MAX ) + VIN(MAX ) • IQ(MAX ) (1) 1) Attaching the part to a larger copper footprint will enable better heat transfer from the device, especially on PCBs where there are internal ground and power planes. For all practical purposes, equation (1) can be reduced to the following expression: (2) 2) Place the input and output capacitors close to the device for optimal transient response and device behaviour. Looking at a typical application, 3.3V to 2.8V at 150mA: VIN(MAX) = 3.3 + 5% = 3.465V VOUT(MIN) = 2.8V - 2% = 2.744V IOUT = 150mA TA = 85°C 3) While the external resistor divider does not need to be close to the device, care should be taken to avoid routing the connections next to any lines carrying large amounts of noise. The simplest solution is to place these resistors close to the device and routing the top of R1 to the load if not adjacent to the part. Inserting these values into equation (2) gives us: 4) Connect all ground connections directly to the ground plane. If there is no ground plane, connect to a common local ground point before connecting to board ground. Using this figure, we can calculate the maximum thermal impedance allowable to maintain TJ ≤ 125°C: θ JA (MAX ) = (T J(MAX ) − TA (MAX ) ) PD(MAX ) = Typical Characteristics (125 − 85) = 370°C / W Dropout Voltage vs. Output Voltage 0.108 vs. Output Current 250 With the standard SOT-23-5 Land Pattern shown at the end of this datasheet, and minimum trace widths, the thermal impedance junction to ambient for SC553 is 256°C/W. Thus no additional heatsinking is required for this example. 225 200 Top to bottom: IOUT = 150mA IOUT = 100mA IOUT = 50mA VD (mV) 175 The junction temperature can be reduced further (or higher power dissipation can be allowed) by the use of larger trace widths and connecting PCB copper to the GND pin (pin 2), which connects directly to the device substrate. Adding approximately one square inch of PCB copper to pin 2 will reduce θ JA to approximately 130°C/W and T J(MAX) for the example above to approximately 100°C. The use of multi layer boards with internal ground/power planes will lower the junction temperature and improve overall output voltage accuracy. 2004 Semtech Corp. TA = 25°C 150 125 100 75 50 25 0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 VOUT (V) 6 www.semtech.com SC553 POWER MANAGEMENT Outline Drawing - SOT-23-5 Land Pattern - SOT-23-5 This land pattern is for reference only. Consult your manufacturing group to ensure you meet your company’s manufacturability guidelines. Contact Information Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805)498-2111 FAX (805)498-3804 2004 Semtech Corp. 7 www.semtech.com