ZXLD1356DACTC Diodes Zetex, ZXLD1356DACTC Datasheet - Page 26

• Manufacturer Part Number: ZXLD1356DACTC
• Description: IC LED DRIVER WHITE BCKLGT 6-DFN
• Manufacturer: Diodes Zetex
• Type: Backlight, White LEDr

Specifications of ZXLD1356DACTC

• Topology: PWM, Step-Down (Buck)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: Automotive, Backlight
• Type - Secondary: High Brightness LED (HBLED), White LED
• Frequency: 500kHz
• Voltage - Supply: 6 V ~ 60 V
• Voltage - Output: 60V
• Mounting Type: Surface Mount
• Package / Case: 6-DFN
• Operating Temperature: -40°C ~ 125°C
• Current - Output / Channel: 550mA
• Internal Switch(s): Yes
• Efficiency: 97%
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ZXLD1356DACTR

A Product Line of
Diodes Incorporated
ZXLD1356
Application Information
(Continued)
Dimming Output Current Using PWM
Low frequency PWM mode
When the ADJ pin is driven with a low frequency PWM signal (eg 100Hz), with a high level voltage VADJ and a low level of zero,
the output of the internal low pass filter will swing between 0V and VADJ, causing the input to the shutdown circuit to fall below
its turn-off threshold (200mV nom) when the ADJ pin is low. This will cause the output current to be switched on and off at the
PWM frequency, resulting in an average output current IOUTavg proportional to the PWM duty cycle. (See Figure 4 - Low
frequency PWM operating waveforms).
Low frequency PWM operating waveforms
The average value of output current in this mode is given by:
0
2 .
D
=
PWM
for DPWM > 0.001
I
OUTavg
R
S
This mode is preferable if optimum LED 'whiteness' is required. It will also provide the widest possible dimming range (approx.
1000:1) and higher efficiency at the expense of greater output ripple.
26 of 29
ZXLD1356
December 2010
www.diodes.com
© Diodes Incorporated
Document number: DS33470 Rev. 3 - 2