Preliminary data

This is preliminary information on a new product now in development or undergoing evaluation. Details are subject to

change without notice.

February 2011

Doc ID 18462 Rev 1

1/12

1

SEA05L

Advanced constant voltage and constant current controller

with very efficient LED pilot-lamp driver

Features

Applications

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.

Figure 1.

Block diagram

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

Packing

SEA05LTR

SOT23-6L

Tape & reel

SOT23-6L (plastic package)

Out

LD

Vctrl

Isense

+

-

+

-

1.23 V

2.5 V

1

2

5

3

4

6

50m V

OSC

GND

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