MAX1739EEP+ Maxim Integrated Products, MAX1739EEP+ Datasheet - Page 10

• Manufacturer Part Number: MAX1739EEP+
• Description: Display Drivers Wide Brightness Rang e CCFL Backlight Con
• Manufacturer: Maxim Integrated Products

Specifications of MAX1739EEP+

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MAX1739/MAX1839 regulate the brightness of a
CCFL in three ways:
1) Linearly controlling the lamp current.
2) Digitally pulse-width modulating (or chopping) the
lamp current (DPWM).
3) Using both methods simultaneously for widest dim-
ming range.
DPWM is implemented by pulse-width modulating the
lamp current at a rate faster than the human eye can
Wide Brightness Range
CCFL Backlight Controllers
Figure 1. Brightness Control Methods
10
______________________________________________________________________________________
V
V
(DAC SET TO MIDSCALE)
EFFECTIVE BRIGHTNESS IS:
50% IN CONTINUOUS AND DPWM CONTROL
25% IN COMBINED CONTROL
MINDAC
CTL
CONTINUOUS CURRENT CONTROL
= V
Detailed Description
CRF
= 0
/2 or BRIGHT[4:0] = 10,000
V
LAMP CURRENT
V
TRANSFORMER
VOLTAGE
V
CSAV
V
CTAP
CTAP
CSAV
detect. Figure 1 shows the current and voltage wave-
forms for the three operating modes with the brightness
control set to 50% of full scale.
The MAX1739/MAX1839 include a 5.3V linear regulator
to power most of the internal circuitry, drivers for the
buck and Royer switches, and the synchronizable
DPWM oscillator. The MAX1739/MAX1839 are very flex-
ible and include a variety of operating modes, an ana-
log interface, an SMBus interface (MAX1739 only), a
shutdown mode, lamp-out detection, and buck-switch
short detection.
CURRENT + DPWM CONTROL
DPWM CONTROL