ZSLS7025ZI1R ZMDI, ZSLS7025ZI1R Datasheet - Page 13

• Manufacturer Part Number: ZSLS7025ZI1R
• Description: LED Lighting Drivers LED Driver
• Manufacturer: ZMDI

Specifications of ZSLS7025ZI1R

• Rohs: yes
• Input Voltage: 5 V
• Maximum Supply Current: 400 uA
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Package / Case: SOIC-8
• Minimum Operating Temperature: - 40 C

2.6.2
As shown in Figure 2.3, a filtered PWM signal can be used as an adjustable DC voltage for LED dimming control,
and it functions the same as the DC control signal described in section 2.6.1. An external RC filter converts the
PWM signal to a DC voltage, which is summed with the FB voltage to regulate the output current. Using a fixed
frequency PWM signal and changing the duty cycle adjusts the average LED current. The LED current can be
calculated with equation (4):
Where
The LED current is inversely proportional to the PWM duty cycle; i.e., when the PWM signal has a 100% duty
cycle, the output current is minimum, ideally zero, and when the PWM signal has a 0% duty cycle, the output
current is at its maximum. See the example in section 4.4 for more details.
Note: Care must be taken to ensure that the minimum required current is not already exceeded when the LEDs
are connected to V
Figure 2.3
-
Data Sheet
June 28, 2012
ZSLS7025
Boost LED Driver
I
V
V
D
OUT
FB
PWM
PWM
Dimming Control Using an RC Filter to Convert a PWM Signal to a DC Voltage
I
= Output current through the LED(s) with a PWM control voltage
= Internal feedback reference voltage (see section 1.3, parameter 1.3.11)
= External PWM control voltage
= Duty cycle of the PWM control signal
OUT
RC Filter PWM Dimming Circuit

V
FB
IN
© 2012 Zentrum Mikroelektronik Dresden AG — Rev.1.00
All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without
the prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.
V
.
IN

C
=5 to 100 VDC
C




VDD
IN
R
3


R
V
VDD
PWM
R
R
R
FB
TOFF
4


D
R
PWM
5
VDD
TOFF
ADJ
GND
ZSLS7025

V
FB
L
1





GATE
OVP
CS
FB
PWM Control Signal
Q
R
1
CS
D
1
R
R
R
1
2
5
C
OUT
R
4
R
3
C
1
String
LED
R
FB
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