LTC1427-50 Datasheet, PDF (1/8 Pages) Linear Technology – Micropower, 10-Bit Current Output DAC with SMBus Serial Interface

LTC1427-50
Micropower, 10-Bit Current
Output DAC with SMBus
Serial Interface
FEATURES
s _{Precision 50µA, ±1.5% Initial Full-Scale Output}
Current, ±2.5% Over Temperature
s _{Wide Output Voltage DC Compliance: – 15V to}
(V_CC – 1.3V)
s _{Wide Supply Range: 2.7V ≤ VCC ≤ 5.5V}
s _{Supply Current in Shutdown: 10µA Typ}
s _{Low Supply Current: 115µA Typ}
s _{Available in 8-Pin SO}
s _{SMBus Serial Interface}
s _{Four Selectable SMBus Addresses}
s _{DAC Powers Up at Zero or Midscale}
s _{DAC Contents Are Retained in Shutdown}
U
APPLICATIONS
s _{LCD Contrast and Backlight Brightness Control}
s _{Power Supply Voltage Adjustment}
s _{Battery Charger Voltage/Current Adjustment}
s _{GaAs FET Bias Adjustment}
s _{Trimmer Pot Elimination}
DESCRIPTION
The LTC^®1427-50 is a micropower, 10-Bit current output
DAC with an output range of 0µA to 50µA. The DAC output is
guaranteed monotonic and DNL is less than 0.9LSB under all
operating conditions. Full-scale accuracy is ±2.5% over
the commercial temperature range. The LTC1427-50 oper-
ates with power supply voltages from 2.7V to 5.5V and the
DAC current source output can be biased from (V_CC – 1.3V)
to – 15V.
The LTC1427-50 communicates with external circuitry by
using the SMBus serial interface. It acts as an SMBus slave
device using one of four selectable SMBus addresses set by
the two address pins AD0 and AD1 .
On power-up, the DAC output assumes midrange or zero
scale, depending on the logic state of the two address pins.
The LTC1427-50 can be shut down through the SHDN pin or
by setting the SHDN bit = 1 in the SMBus command byte.
Digital data for the DAC output is retained internally and the
supply current drops to 10µA typically when in shutdown.
The LTC1427-50 is available in an 8-pin SO package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
Digitally Controlled LCD Bias Generator
L1
D1
V_OUT*
6
5
R1
V_IN
SW
226k
LT1317
1%
2 TO 4
CELLS
SHDN
3
SHDN
2
FB
1µF
GND
V_C
R2
C1
12.1k
1µF
4
1
1%
4700pF
100k
L1 = 10 µH SUMIDA CD43
MURATA-ERIE LQH3C
OR COILCRAFT DO1608
D1 =MBR0530
*V_OUT = 12.7V TO 24V IN 11mV STEPS
15mA (2 CELLS)
35mA ( 3 CELLS)
V_CC
3.3V
LTC1427-50
1
SHDN
2
AD1
3
AD0
8
V_CC
7
I_OUT
6
SCL
4
GND
5
SDA
µPU
(e.g., 8051)
P1.2
P1.1
P1.0
1427 TA02
1