ZLED7002

Toggle (Side-Step) Dual-Channel LED Driver

© 2011 Zentrum Mikroelektronik Dresden AG — Rev. 3.0

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Brief Description

The ZLED7002 toggle (side-step) dual-channel LED

driver is one of our ZLED family of LED control ICs. It

operates in the lower DC voltage supply range of 2.7V to

5.5V. This unique LED driver is capable of controlling a

MAIN channel and a SUB channel. Typically, only one of

the two channels is active and the ZLED7002 toggles

between the channels automatically in response to the

voltage supply level and the related voltage at the UV

(under-voltage protection) pin. A high-to-low transition of

the power supply causes the output current to switch

from the MAIN channel to the SUB channel if the UV pin

sition switches the output current from the SUB channel

to the MAIN channel if the UV pin voltage is 80mV (typi-

cal) above the under-voltage threshold.

The MAIN channel is a configurable constant current

source driving the MAIN LED string with a maximum

current draw of 250mA. The MAIN LED channel current

is set by an external resistor (R3) connected to the Iset

pin. Alternately, the SUB channel is activated when the

ZLED7002’s SUB pin is pulled to ground. Its current is

determined by the forward voltage of the SUB LED and

external components. The SUB channel can drive up to

100mA current through the LED channel when active.

The ZLED7002 enables voltage-level indicator applica-

tions and low-power battery-driven lighting applications

that require switching to a lower-current LED channel

when the supply is low, which extends the lighting life-

low as 0.1V when the MAIN channel output current is

~200mA), the ZLED7002 is optimal for battery-powered

applications. Capable of operating efficiently with DC

voltage supplies ranging from 2.7V to 5.5V, it is ideal for

small portable lighting applications.

The ZLED7002 can also reduce bill-of-material costs

because very few external components are required for

most applications, making it an optimal fit for small

devices for which lighting lifetime is critical. Only four

resistors, a diode, and a capacitor are needed for a

typical basic application.

Features

• Automatic MAIN channel short-circuit protection

switches the output current to the SUB channel

if the MAIN LED is shorted

• Under-voltage power supply detection

• Over-temperature protection

Benefits

• Extends lighting life-time by switching to a lower-

current LED channel when the supply is low

• 80mV (typical) hysteresis prevents unintended

switching activation due to power supply ripple

• Ultra low quiescent current: 250µA typical

• Very few external components needed for operation

Available Support

• Evaluation Kit

Physical Characteristics

• Voltage supply: 2.7V to 5.5V DC

• Operating temperature: -25°C to 85°C

• Small SOP8 package

For additional information on our ZLED driver family,

ZLED7002 Typical Application Circuit