SEA05TR STMicroelectronics

SEA05 Advanced constant voltage and constant current controller Features Constant voltage and constant current control Wide operating V range 3.5 - 36 V CC Low quiescent consumption: 200 A Voltage reference: 2.5 V Voltage control loop accuracy +/- 0.5% Current sense threshold: 50 mV SOT23 - 6L Open-drain output stage adequately rated in terms of power dissipation Low external component count the frequency compensation components (R-C SOT23-6L micro package networks) for both loops. The device, housed in one of the smallest Applications available package, is ideal for space-shrunk applications such as adapters and chargers. Battery chargers AC-DC adapters Figure 1. Internal schematic LED drivers Vcc 2.5 V 6 Description 1.23 V 5 Out + - The SEA05 is a highly integrated solution for 3 Vctrl SMPS applications requiring a dual control loop to perform CV (constant voltage) and CC (constant + current) regulation. 2 Gnd - The device integrates a voltage reference, two op- 4 1 amps (with OR-ed open-drain outputs), and a low- side current sensing circuit. Ictrl Isense The voltage reference, along with one op-amp, is the core of the voltage control loop the current Table 1. Device summary sensing circuit and the other op-amp make up the Order code Package Packing current control loop. SEA05TR SOT23-6L Tape and reel The external components needed to complete the two control loops are: a resistor divider that senses the output of the power supply and fixes the voltage regulation setpoint at the specified value a sense resistor that feeds the current sensing circuit with a voltage proportional to the dc output current this resistor determines the current regulation setpoint and must be April 2010 Doc ID 17014 Rev 1 1/10 www.st.com 10 Pin description SEA05 1 Pin description Figure 2. Pin configuration 6666 Isense 1111 Vcc GND Out 5555 2222 Vctrl 3333 4444 Ictrl Note: The adjacent pins have the same AMR to increase the robustness of the IC against accidental short circuit among pins. Table 2. Pin description n. Name Function Inverting input of the current loop op-amp. The pin is tied to the cold end of the 1 Isense current sense resistor through a decoupling resistor. Ground. Return of the bias current of the device. 0 V reference for all voltages. 2GND The pin should be tied as close to the ground output terminal of the converter as possible to minimize load current effect on the voltage regulation setpoint. Inverting input of the voltage loop op-amp. The pin is tied to the mid-point of a 3Vctrl resistor divider that senses the output voltage. Non-inverting input of the current loop op-amp. It is tied directly to the hot 4Ictrl (negative) end of the current sense resistor Common open-drain output of the two internal op-amps. The pin, able to sink 5OUT current only, is connected to the branch of the optocouplers photodiode to transmit the error signal to the primary side. Supply Voltage of the device. A small bypass capacitor (0.1 F typ.) to GND, 6Vcc located as close to ICs pins as possible, might be useful to get a clean supply voltage. 2/10 Doc ID 17014 Rev 1