LP3943 Datasheet, PDF (10/21 Pages) National Semiconductor (TI) – RGB/White/Blue 16-LED Fun Light Driver

LP3943
SNVS256A – MAY 2004 – REVISED MAY 2004
www.ti.com
ack from slave
ack from slave repeated start ack from slave data from slave ack from master
start msb Chip Address lsb w ack msb Register Add lsb ack rs msb Chip Address lsb r ack msb DATA lsb
ack stop
SC
L
SD
A
star
t
id = h'xx
w
ac
k
addr =
h'00
ac r
ks
id = h'xx
r
ac
k
w = write (SDA = “0”)
r = read (SDA = “1”)
ack = acknowledge (SDA pulled LOW by either master or slave)
rs = repeated start
xx = 60 to 67
Figure 7. LP3943 Register Read
address h'00
data
ac sto
kp
AUTO INCREMENT
Auto increment is a special feature supported by the LP3943 to eliminate repeated chip and register addressing
when data are to be written to or read from registers in sequential order. The auto increment bit is inside the
register address byte, as shown in Figure 8. Auto increment is enabled when this bit is programmed to “1” and
disabled when it is programmed to “0”.
Bits 5, 6 and 7 in the register address byte should always be zero.
Figure 8. Register Address Byte
In the READ mode, when auto increment is enabled, I²C master could receive any number of bytes from LP3943
without selecting chip address and register address again. Every time the I²C master reads a register, the
LP3943 will increment the register address and the next data register will be read. When I²C master reaches the
last register (09H), the register address will roll over to 00H.
In the WRITE mode, when auto increment is enabled, the LP3943 will increment the register address every time
I²C master writes to register. When the last register (09H register) is reached, the register address will roll over to
02H, not 00H, because the first two registers in LP3943 are read-only registers. It is possible to write to the first
two registers independently, and the LP3943 will acknowledge, but the data will be ignored.
If auto increment is disabled, and the I²C master does not change register address, it will continue to write data
into the same register.
Figure 9. Programming with Auto Increment Disabled (in WRITE Mode)
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