Document
www.DataSheet4U.com
SEA05
Advanced constant voltage and constant current controller
Features
■ ■ ■ ■ ■ ■ ■ ■ ■
Constant voltage and constant current control Wide operating VCC range [3.5 - 36] V Low quiescent consumption: 200 µA Voltage reference: 2.5 V Voltage control loop accuracy +/- 0.5% Current sense threshold: 50 mV Open-drain output stage Low external component count SOT23-6L micro package
SOT23 - 6L adequately rated in terms of power dissipation; the frequency compensation components (R-C networks) for both loops. The device, housed in one of the smallest available package, is ideal for space-shrunk applications such as adapters and chargers. Figure 1. Internal schematic
2.5 V 1.23 V Vcc 6
Applications
■ ■ ■
Battery chargers AC-DC adapters LED drivers
Description
The SEA05 is a highly integrated solution for SMPS applications requiring a dual control loop to perform CV (constant voltage) and CC (constant current) regulation. The device integrates a voltage reference, two opamps (with OR-ed open-drain outputs), and a lowside current sensing circuit. The voltage reference, along with one op-amp, is the core of the voltage control loop; the current sensing circuit and the other op-amp make up the current control loop. 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 Table 1.
+ + -
5 3
Out Vctrl
2 1 Isense
Gnd
4 Ictrl
Device summary
Package SOT23-6L Packing Tape and reel
Order code SEA05TR
April 2010
Doc ID 17014 Rev 1
1/10
www.st.com 10
www.DataSheet4U.com
Pin description
SEA05
1
Pin description
Figure 2. Pin configuration
Isense GND Vctrl
Note:
1 2 3
6 5 4
Vcc Out Ictrl
The adjacent pins have the same AMR to increase the robustness of the IC against accidental short circuit among pins. Table 2.
n. 1
Pin description
Name Isense Function Inverting input of the current loop op-amp. The pin is tied to the cold end of the current sense resistor through a decoupling resistor. Ground. Return of the bias current of the device. 0 V reference for all voltages. 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 resistor divider that senses the output voltage. Non-inverting input of the current loop op-amp. It is tied directly to the hot (negative) end of the current sense resistor Common open-drain output of the two internal op-amps. The pin, able to sink current only, is connected to the branch of the optocoupler’s photodiode to transmit the error signal to the primary side. Supply Voltage of the device. A sm.