LTC1428CS8-50 Linear Technology, LTC1428CS8-50 Datasheet - Page 6

• Manufacturer Part Number: LTC1428CS8-50
• Description: IC D/A CONV 8BIT SINK OUT 8-SOIC
• Manufacturer: Linear Technology

Specifications of LTC1428CS8-50

• Number Of Bits: 8
• Data Interface: Serial
• Number Of Converters: 1
• Voltage Supply Source: Single Supply
• Power Dissipation (max): 120µW
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Settling Time: -

SERIAL I/O OPERATI G SEQUE CE
D
LTC1428-50
8-BIT CURRENT OUTPUT DAC
The LTC1428-50 is an 8-bit, current sink output digital-to-
analog (DAC) converter. The LTC1428-50 is guaranteed
monotonic and is digitally adjustable in 256 equal steps.
Upon power up, the counter resets to 1000000B and the
DAC output assumes midrange. The I
from 2V to 10V. The LTC1428-50 features a full-scale
output current of 50 A 3% at room temperature ( 5%
over temperature). This device also includes a flexible
serial digital interface that allows easy interconnection to
a variety of digital systems.
DIGITAL INTERFACE
Automatic Mode Selection
The LTC1428-50 includes a serial interface capable of com-
municating with the host system using one of three pro-
tocols; standard 3-wire mode, a 2-wire up/down pulse mode
and a 1-wire increment-only pulse mode. The LTC1428-50
is designed to autoconfigure itself depending on the method
6
APPLICATIONS
CLK
OUT
D
CS
IN
Hi-Z
3-WIRE MODE
t
t
CSS
CKS
CS GOES
Figure 2. LTC1428-50 Operating Modes
t
LOW
DV
D7
D7
D
INCREMENT/
DECREMENT
POWER-UP
GOES LOW
IN
U
(UP/DN)
D6
INFORMATION
U
D6
PULSE MODE
CS STAYS
HIGH
U
D5
W
OUT
INCREMENT-
Figure 1. 3-Wire Interface Timing Specification
D
HIGH
t
D5
DS
IN
pin can be biased
ONLY
STAYS
D4
1428-50 F02
U
D4
U
t
DH
t
CSLO
D3
D3
of data presentation. A diagram illustrating this
autodetection behavior is shown in Figure 2. At power-up,
the interface is set to 1-wire pulse mode. If the CS line ever
goes low (as it will at the beginning of a valid 3-wire serial
transfer) the chip immediately reconfigures itself into 3-wire
mode and remains in this mode until power is cycled. If CS
stays high, the device stays in pulse mode and monitors the
UP/DN pin to determine whether to switch to 2-wire mode.
If UP/DN ever goes low (as it will the first time a “down”
command is given) the chip switches into 2-wire pulse
mode and remains in this mode until power is cycled. In a
properly configured 1-wire system, CS and UP/DN will
always remain high. 2-wire pulse mode systems must
provide a single logic low pulse before the first data pulses
are sent to prevent the LTC1428-50 from remaining in
1-wire mode if the first several pulses are logic high.
Standard 3-Wire Mode (Figure 3)
Refer to the Serial Interface Operating Sequence in Figure
1. When operating in 3-wire mode, the LTC1428-50 will
interface directly with most standard 3- or 4-wire serial
interface systems. The clock (CLK) input synchronizes the
data transfer with each input bit captured at the rising edge
of CLK and each output data bit shifted through D
falling edge. Data is shifted into and out of the LTC1428-
50 starting with the MSB bit. A falling edge at CS initiates
the data transfer and brings the D
The serial 8-bit data representing the new DAC setting is
shifted into the D
setting is shifted out of the D
t
DO
D2
D2
t
CKHI
IN
D1
pin. Simultaneously, the previous DAC
t
D1
CKLO
OUT
D0
D0
OUT
pin. After the new data is
pin out of three-state.
t
CKH
t
CSH
D7
t
DZ
t
CSHI
OUT
Hi-Z
at the
1428-50 F01