Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsData collecting ICsData acquisition IC - DA converter (DAC) SOIC 8

LTC1257

Complete Single Supply

12-Bit Voltage Output

DAC in SO-8

CODE

DNL ERROR (LSBs)

0.5

0.0

–0.5

1024 2048 2560

1257 TA05

512 1536 3072 3584

4098

Differential Nonlinearity

vs Input Code

■

Digital Offset/Gain Adjustment

■

Industrial Process Control

■

Automatic Test Equipment

The LTC

1257 is a complete single supply, 12-bit voltage

output D/A converter (DAC) in an SO-8 package. The

LTC1257 includes an output buffer amplifier, 2.048V

voltage reference and an easy to use three-wire cascadable

serial interface. An external reference can be used to

override the internal reference and extend the output

voltage range to 12V. The power supply current is a low

350µA when operating from a 5V supply, making the

LTC1257 ideal for battery-powered applications. The space-

saving 8-pin SO package and operation with no external

components provide the smallest 12-bit D/A system

available.

■

8-Pin SO Package

■

Buffered Voltage Output

■

Built-In 2.048V Reference

■

500µV/LSB with 2.048V Full Scale

■

1/2LSB Max DNL Error

■

Guaranteed 12-Bit Monotonic

■

3-Wire Cascadable Serial Interface

■

Wide Single Supply Range: V

= 4.75V to 15.75V

■

Low Power: I

Typ = 350µA with 5V Supply

, LTC and LT are registered trademarks of Linear Technology Corporation.

µP

0.1µF

CONTROL OUTPUT 1

CONTROL OUTPUT 2

REF

GND

OUT

CLK

LOAD

OUT

LTC1257

REF

GND

OUT

CLK

LOAD

OUT

LTC1257

TO NEXT DAC

1257 TA01

Daisy-Chained Control Outputs

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

Summary of content (12 pages)

PAGE 1
LTC1257 Complete Single Supply 12-Bit Voltage Output DAC in SO-8 U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO 8-Pin SO Package Buffered Voltage Output Built-In 2.048V Reference 500µV/LSB with 2.048V Full Scale 1/2LSB Max DNL Error Guaranteed 12-Bit Monotonic 3-Wire Cascadable Serial Interface Wide Single Supply Range: VCC = 4.75V to 15.
PAGE 2
LTC1257 W W W AXI U U ABSOLUTE RATI GS U U W PACKAGE/ORDER I FOR ATIO (Note 1) VCC to GND ............................................ – 0.5V to 16.5V TTL Input Voltage .......................... – 0.5V to VCC + 0.5V VOUT .............................................. – 0.5V to VCC + 0.5V REF ................................................ – 0.5V to VCC + 0.5V Operating Temperature Range LTC1257C ............................................. 0°C to 70°C LTC1257I ...................................
PAGE 3
LTC1257 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = TMIN to TMAX. VCC = 4.75V to 15.75V, internal or external reference (2.475V ≤ VREF ≤ VCC – 2.7V), unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS 15.75 V 600 1500 µA µA 60 mA 60 mA 500 Ω Power Supply VCC Positive Supply Voltage For Specified Performance ● ICC Supply Current 4.75V ≤ VCC ≤ 5.25V 4.
PAGE 4
LTC1257 U W TYPICAL PERFOR A CE CHARACTERISTICS Minimum Supply Voltage vs Load Current #2 Minimum Supply Voltage vs Load Current #1 4.4 4.2 4.0 3.8 3.6 3.4 3.2 3.0 0.01 0.1 1 OUTPUT LOAD CURRENT (mA) VREF = 10V VOUT = FULL SCALE TA = 25°C 14.5 14.0 13.5 13.0 12.5 12.0 0.1 1 OUTPUT LOAD CURRENT (mA) OUTPUT VOLTAGE SWING (V) 0.39 4.0 ZERO SCALE RL TIED TO VCC 3.5 3.0 FULL SCALE RL TIED TO GND 2.5 2.0 1.5 1.0 0.5 0.34 4 100 1k LOAD RESISTANCE (Ω) 0.8 2.0480 2.0475 2.
PAGE 5
LTC1257 U W TYPICAL PERFOR A CE CHARACTERISTICS Reference Compensation Resistance vs CL Differential Nonlinearity (DNL) 0.0 –0.5 0 512 1024 1536 2048 2560 3072 3584 4098 CODE 70 CODE = FFFH BW = 3Hz TO 1MHz GAIN = 1100× 60 50 40 0.1V/DIV REFERENCE COMPENSATION RESISTANCE (Ω) DNL ERROR (LSBs) 0.5 Broadband Noise 30 20 10 0 0.01 0.1 1257 TA05 1 CL (µF) 10 100 TIME = 5ms/DIV 1257 G12 1257 G11 U U U PI FU CTIO S CLK (Pin 1): The TTL level input for the serial interface clock.
PAGE 6
LTC1257 U U DEFI ITIO S LSB: The least significant bit or the ideal voltage difference between two successive codes. LSB = n = VOS = VFS = (VFS – VOS)/2n – 1 The number of digital input bits The zero code error or offset of the DAC The full-scale output voltage of the DAC measured when all bits are set to 1 Resolution: The resolution is the number of DAC output states (2n) that divide the full-scale range. The resolution does not imply linearity.
PAGE 7
LTC1257 W BLOCK DIAGRA LOGIC SUPPLY CLK DIN 5V REGULATOR VCC 12-BIT SHIFT REGISTER DOUT 12 LOAD GND 12-BIT LATCH 12 REF 2.
PAGE 8
LTC1257 U OPERATIO Serial Interface Reference The data on the DIN input is loaded into the shift register on the rising edge of the clock. The MSB is loaded first and the LSB last. The DAC register loads the data from the shift register when LOAD is pulled low, and remains transparent until LOAD is pulled high and the data is latched. The LTC1257 includes an internal 2.048V reference, making 1LSB equal to 500µV.
PAGE 9
LTC1257 U TYPICAL APPLICATIO S Auto Ranging 8-Channel ADC with Shutdown 22µF 5V VCC CH0 8 ANALOG INPUT CHANNELS CS DOUT • • • LTC1296 µP CLK DIN CH7 COM REF + REF – SSO 50k 50k 5V 74HC04 0.1µF VCC DIN 100Ω VOUT LTC1257 0.1µF DIN 100Ω VOUT LTC1257 GND VREF 0.1µF LOAD DOUT GND VREF VCC CLK CLK LOAD DOUT 1257 TA02 12-Bit Single 5V Control System with Shutdown 5V 100k 10k 10µF 2N3906 VCC –IN – J DATA CLK GND COMMON µP DAC LOAD LTC1297 ADC LT1025A + CLK DOUT 0.
PAGE 10
LTC1257 U PACKAGE DESCRIPTIO N8 Package 8-Lead PDIP (Narrow .300 Inch) (Reference LTC DWG # 05-08-1510) 0.400* (10.160) MAX 8 7 6 5 1 2 3 4 0.255 ± 0.015* (6.477 ± 0.381) 0.300 – 0.325 (7.620 – 8.255) 0.009 – 0.015 (0.229 – 0.381) ( +0.035 0.325 –0.015 8.255 +0.889 –0.381 ) 0.045 – 0.065 (1.143 – 1.651) 0.065 (1.651) TYP 0.100 (2.54) BSC *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm) 10 0.130 ± 0.005 (3.
PAGE 11
LTC1257 U PACKAGE DESCRIPTIO S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) 0.189 – 0.197* (4.801 – 5.004) 8 7 6 5 0.150 – 0.157** (3.810 – 3.988) 0.228 – 0.244 (5.791 – 6.197) 1 0.010 – 0.020 × 45° (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 0.053 – 0.069 (1.346 – 1.752) 0°– 8° TYP 0.016 – 0.050 (0.406 – 1.270) 0.014 – 0.019 (0.355 – 0.483) TYP *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.
PAGE 12
LTC1257 UO TYPICAL APPLICATI Driving LTC1257 with Optoisolators 12V 2k 5% MOC5008 CLK LT1021-5 VOUT VIN 2k 5% 2k 5% 0.1µF CLK VCC 6 VREF DIN VOUT LOAD LTC1257 1 4 2 DOUT VOUT GND 5 MOC5008 DIN 6 1 4 2 5 MOC5008 LOAD 1 6 4 2 5 1257 TA07 RELATED PARTS PART NUMBER 12 Bit LTC1446/LTC1446L DESCRIPTION COMMENTS Dual 12-Bit VOUT DACs in SO-8 Package LTC1448 Dual 12-Bit VOUT DAC in SO-8 Package, VCC: 2.7V to 5.