ZLED7015 Datasheet

© 2016 Integrated Device Technology, Inc.

15

April 20, 2016

S

S

R

R

R

V

V

FB

OUT

)

(

3 +

×

=

(

)

S

R

R

R

V

D

V

R

V

I

FB

PWM

PWM

FB

OUT













+

−

×

×

−

=

5

3

4

The output current controlled by the PWM voltage on FB can be calculated using equation (3):

(3)

Where

IOUT = Output current through the LED(s) with a PWM control voltage

VFB = Internal feedback reference voltage (see Table 1.3, parameter 1.3.7)

VPWM = External PWM control voltage

DPWM = Duty cycle of the PWM control signal

2.2.4

Microcontroller LED Control

A microcontroller can control the LED output current by providing a PWM control signal to the FB pin as described

in section 2.2.3.

Depending on the application, the microcontroller can also be used to control the shutdown circuitry via the EN

pin (see section 2.1) providing a fast and smooth transition to shutdown.

2.2.5

Constant Voltage Application

In addition to functioning as a constant-current boost converter for driving an LED string, the ZLED7015 can be

configured as a constant-voltage boost converter for other applications. Figure 2.4 demonstrates a typical circuit

for this application.

The output voltage controlled by the values of R3 and RS can be calculated using equation (4):

(4)

Where

VOUT = Output voltage to the load

VFB = Internal feedback reference voltage (Table 1.3, parameter 1.3.7)