ISL97632 Intersil Corporation, ISL97632 Datasheet - Page 4

• Manufacturer Part Number: ISL97632
• Description: White LED Driver
• Manufacturer: Intersil Corporation

Single-Wire Serial Interface
The ISL97632 uses a simple single-wire serial interface for
programming the output brightness of the LEDs. A 5-bit
interface is used to give a total of 32 levels of output
brightness. The interface uses a normally high connection
for use with open-drain driving schemes and Intersil’s
proprietary XSD bus. When held low for between 15µs and
45µs, the interface registers a logic 1. When held low for
between 90µs and 120µs the interface registers a logic 0.
When held low for greater that 215µs, the interface loads the
last 5 bits into the brightness control register and updates
the brightness level. The required minimum high time is 3µs.
This simple single-wire programming is summarized as
follow:
• Logic 0 = Negative pulse >90µs and <120µs
• Logic 1 = Negative pulse >15µs and <45µs
• Load = Negative pulse >215µs
Figure 1 shows an example of programming a binary code of
10100 and load it in to the device serial register.
The serial interface is automatically reset to 0 when the
device is disabled, or enters UVLO. Therefore, when the part
is enabled, the output brightness is automatically set to the
minimum level.
30µs
0
'1'
4
200
'0'
FIGURE 1. SINGLE-WIRE XSD INTERFACE
400
'1'
ISL97632
600
100µs
'0'
800
'0'
1000
'LOAD'
220µs
1200
µs
April 10, 2007
FN9239.2