SEA05LTR STMicroelectronics

SEA05L Advanced constant voltage and constant current controller with very efficient LED pilot-lamp driver Preliminary data Features Constant voltage and constant current control Very efficient LED pilot-lamp driver Wide operating V range (3.5 V - 36 V) CC SOT23-6L (plastic package) Low quiescent consumption: 250 A Figure 1. Block diagram Voltage reference: 2.5 V V CC Voltage control loop accuracy 0.5% 6 2.5 V 1.23 V Current sense threshold: 50 mV 5 + Out Current control loop accuracy 4% - 3 Low external component count 50m V Vctrl + Open-drain output stage - 4 SOT23-6L package LD OSC 2 1 Applications GND Isense AC-DC adapter with LED pilot-lamp The voltage reference, along with one op-amp, is Battery chargers with LED pilot-lamp the core of the voltage control loop. The current sensing circuit and the other op-amp make up the SMPS with LED pilot-lamp current control loop. Description The external components needed to complete the two control loops are: The device is a highly integrated solution for - a resistor divider that senses the output of the SMPS applications, with an LED pilot-lamp power supply and fixes the voltage regulation requiring a dual control loop to perform CV setpoint at the specified value (constant voltage) and CC (constant current) regulation. - a sense resistor that feeds the current sensing circuit with a voltage proportional to the DC output The IC allows very efficient LED pilot-lamp driving current this resistor determines the current which helps to reduce the standby consumption of regulation setpoint and must be adequately rated the SMPS. It integrates a voltage reference, two in terms of power dissipation op-amps (with OR-ed open-drain outputs), a low- side current sensing circuit and an LED pilot-lamp - the frequency compensation components (R-C driver pin implemented with an open-drain mosfet networks) for both loops. driven by square waveform with 12.5% duty cycle The device is ideal for space-critical applications. at 1 kHz that allows reducing LED consumption. Table 1. Device summary Order code Package Packing SEA05LTR SOT23-6L Tape & reel February 2011 Doc ID 18462 Rev 1 1/12 This is preliminary information on a new product now in development or undergoing evaluation. Details are subject to www.st.com 1 change without notice.Contents SEA05L Contents 1 Operation 3 2 Application information 6 2.1 Voltage and current control 6 2.2 Compensation 8 2.3 LD pin function 8 3 Package mechanical data 10 4 Revision history . 11 2/12 Doc ID 18462 Rev 1