MAX16808 Maxim Integrated Products, MAX16808 Datasheet - Page 16

• Manufacturer Part Number: MAX16808
• Description: (MAX16807 / MAX16808) Integrated 8-Channel LED Drivers
• Manufacturer: Maxim Integrated Products

Table 1. 4-Wire Serial-Interface Truth Table
Integrated 8-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
The MAX16807/MAX16808 also operate in a stand-
alone mode (see the Typical Operating Circuits ). For
use with a microcontroller, the MAX16807/MAX16808
feature a 4-wire serial interface using DIN, CLK, LE, OE
inputs and DOUT as a data output. This interface is
used to write the LED channels’ data to the MAX16807/
MAX16808. The serial-interface data word length is 8
bits, D0–D7. See Figure 3.
The functions of the five interface pins are as follows:
DIN is the serial-data input, and must be stable when it
is sampled on the rising edge of CLK. Data is shifted in
MSB first. This means that data bit D7 is clocked in first,
followed by 7 more data bits, finishing with the LSB, D0.
CLK is the serial-clock input that shifts data at DIN into
the MAX16807/MAX16808’s 8-bit shift register on its ris-
ing edge.
L = Low Logic Level
H = High Logic Level
X = Don’t Care
P = Present State (Shift Register)
R = Previous State (Latched)
16
SERIAL
INPUT
DATA
DIN
H
L
X
______________________________________________________________________________________
CLOCK
INPUT
CLK
SHIFT REGISTER CONTENTS
D0 D1 D2 … Dn-1
R0 R1 R2 … Rn-1
P0
H
X
L
R0 R1 … Rn-2 Rn-1
R0 R1 … Rn-2 Rn-1
P1 P2 … Pn-1
X
X
…
X
4-Wire Interface
LED Driver
Dn
Rn
Pn
X
INPUT
LOAD
LE
H
L
D0 D1 D2 … Dn-1 Dn
R0 R1 R2
P0 P1 P2
X
LATCH CONTENTS
X
LE is the latch enable input of the MAX16807/
MAX16808 that transfers data from the 8-bit shift regis-
ter to its 8-bit output latch (transparent latch). The data
is latched on the falling edge of LE (Figure 4). The
fourth input (OE) provides output-enable control of the
output drivers. When OE is driven high, the outputs
(OUT0–OUT7) are forced to high impedance without
altering the contents of the output latches. Driving OE
low enables the outputs to follow the state of the output
latches. OE is independent of the operation of the serial
interface operation. Data can be shifted into the serial-
interface shift register and latched, regardless of the
state of OE. DOUT is the serial-data output that shifts
data out from the MAX16807/MAX16808’s 8-bit shift
register on the rising edge of CLK. Data at DIN propa-
gates through the shift register and appears at DOUT
eight clock cycles later. Table 1 shows the 4-wire seri-
al-interface truth table.
X
… Rn-1 Rn
… Pn-1 Pn
…
X
X
BLANKING
INPUT
OE
H
L
D0 D1 D2 …
P0 P1 P2
L
OUTPUT CONTENTS
CURRENT AT OUT_
L
L
…
…
Dn-1 Dn
Pn-1 Pn
L
L