Rainbow Electronics MAX518 - Manual (Page 7)

MAX517/MAX518/MAX519
2-Wire Serial 8-Bit DACs with
Rail-to-Rail Outputs
_______________________________________________________________________________________ 7
Figure 1. MAX517/MAX519 Functional Diagram
_______________Detailed Description
Serial Interface
The MAX517/MAX518/MAX519 use a simple 2-wire
serial interface requiring only two I/O lines (2-wire bus)
of a standard microprocessor (µP) port. Figure 2 shows
the timing diagram for signals on the 2-wire bus.
Figure 3 shows a typical application. The 2-wire bus can
have several devices (in addition to the MAX517/
MAX518/MAX519) attached. The two bus lines (SDA and
SCL) must be high when the bus is not in use. When in
use, the port bits are toggled to generate the appropriate
signals for SDA and SCL. External pull-up resistors are
not required on these lines. The MAX517/MAX518/
MAX519 can be used in applications where pull-up resis-
tors are required (such as in I
2 C systems) to maintain
compatibility with existing circuitry.
The MAX517/MAX518/MAX519 are receive-only devices
and must be controlled by a bus master device. They
operate at SCL rates up to 400kHz. A master device
sends information to the devices by transmitting their
address over the bus and then transmitting the desired
information. Each transmission consists of a START
condition, the MAX517/MAX518/MAX519’s programm-
able slave-address, one or more command-byte/out-
put-byte pairs (or a command byte alone, if it is the last
byte in the transmission), and finally, a STOP condition
(Figure 4).
______________________________________________________________Pin Description
PIN
MAX517 MAX518 MAX519
NAME FUNCTION
1 1 1 OUT0 DAC0 Voltage Output
2 2 4 GND Ground
— — 5 AD3 Address Input 3; sets IC’s slave address
3 3 6 SCL Serial Clock Input
4 4 8 SDA Serial Data Input
— — 9 AD2 Address Input 2; sets IC’s slave address
5 5 10 AD1 Address Input 1; sets IC’s slave address
6 6 11 AD0 Address Input 0; sets IC’s slave address
7 7 12 VDD Power Supply, +5V; used as reference for MAX518
— — 13 REF1 Reference Voltage Input for DAC1
8 — 15 REF0 Reference Voltage Input for DAC0
— 8 16 OUT1 DAC1 Voltage Output
— — 2, 3, 7, 14 N.C. No Connect—not internally connected.
INPUT
LATCH 0
OUTPUT
LATCH 0
START/STOP
DETECTOR
DAC0
INPUT
LATCH 1
8-BIT
SHIFT
REGISTER
OUT0
REF0 (REF1)
(OUT1)
MAX517/MAX519
DECODE
ADDRESS
COMPARATOR
DAC1
OUTPUT
LATCH 1
V
DD
SCL
SDA
AD0 (AD2)
AD1 (AD3)
GND
MAX519 ONLY
( ) ARE FOR MAX519