SEA05L Datasheet, PDF (1/12 Pages) STMicroelectronics – Advanced constant voltage and constant current controller with very efficient LED pilot-lamp driver

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_CC range (3.5 V - 36 V)
■ Low quiescent consumption: 250 µA
■ Voltage reference: 2.5 V
■ Voltage control loop accuracy ± 0.5%
■ Current sense threshold: 50 mV
■ Current control loop accuracy ± 4%
■ Low external component count
■ Open-drain output stage
■ SOT23-6L package
Applications
■ AC-DC adapter with LED pilot-lamp
■ Battery chargers with LED pilot-lamp
■ SMPS with LED pilot-lamp
Description
The device is a highly integrated solution for
SMPS applications, with an LED pilot-lamp
requiring a dual control loop to perform CV
(constant voltage) and CC (constant current)
regulation.
The IC allows very efficient LED pilot-lamp driving
which helps to reduce the standby consumption of
the SMPS. It integrates a voltage reference, two
op-amps (with OR-ed open-drain outputs), a low-
side current sensing circuit and an LED pilot-lamp
driver pin implemented with an open-drain mosfet
driven by square waveform with 12.5% duty cycle
at 1 kHz that allows reducing LED consumption.
SOT23-6L (plastic package)
Figure 1. Block diagram
1.23 V
2.5 V
+
-
V _CC
6
5
3
50mV ₊
-
4
2
GND
1
OSC
Isense
Out
Vctrl
LD
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 adequately rated
in terms of power dissipation
- the frequency compensation components (R-C
networks) for both loops.
The device is ideal for space-critical applications.
Table 1. Device summary
Order code
Package
SEA05LTR
SOT23-6L
Packing
Tape & reel
February 2011
Doc ID 18462 Rev 1
This is preliminary information on a new product now in development or undergoing evaluation. Details are subject to
change without notice.
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