Datasheet

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LTC1454/LTC1454L

Dual 12-Bit Rail-to-Rail

Micropower DACs

Daisy-Chained Control Outputs

Functional Block Diagram: Dual 12-Bit Rail-to-Rail DAC

X1/X2 B

X1/X2 A

CLK

OUT

POWER-ON

RESET

–

12-BIT

DAC A

12-BIT

DAC B

REFOUT

CS/LD

OUT B

REFHI B

REFHI A

REFLO GND

9, 15

LTC1454: 5V

LTC1454L: 3V TO 5V

LTC1454: 2.048V

LTC1454L: 1.22V

OUT A

–

CLR

1454 BD02

24-BIT

SHIFT

REG

AND

DAC

LATCH

µP

Differential Nonlinearity

vs Input Code

CODE

DNL ERROR (LSB)

0.5

0.4

0.3

0.2

0.1

–0.1

–0.2

–0.3

–0.4

–0.5

1024

2048

2560

1454 G08

512 1536

3072

3584

4095

FEATURES

■

12-Bit Resolution

■

Buffered True Rail-to-Rail Voltage Output

■

5V Operation, I

: 700µA Typ (LTC1454)

■

3V Operation, I

: 450µA Typ (LTC1454L)

■

Built-In Reference: 2.048V (LTC1454)

1.220V (LTC1454L)

■

CLR Pin

■

Power-On Reset

■

16-Lead SO Package

■

3-Wire Cascadable Serial Interface

■

Maximum DNL Error: 0.5LSB

■

Low Cost

The LTC

1454/LTC1454L are complete single supply,

dual rail-to-rail voltage output, 12-bit digital-to-analog

converters (DACs) in a 16-lead SO package. They include

an output buffer amplifier with variable gain (×1 or ×2)

and an easy-to-use 3-wire cascadable serial interface.

The LTC1454 has an onboard reference of 2.048V and a

full-scale output of 4.095V in a ×2 gain configuration. It

operates from a single 4.5V to 5.5V supply.

The LTC1454L has an onboard 1.22V reference and a full-

scale output of 2.5V in a ×2 gain configuration. It operates

from a single 2.7V to 5.5V supply.

Low power supply current, excellent DNL and small size

allow these parts to be used in a host of applications where

size, DNL and single supply operation are important.

DESCRIPTION

APPLICATIONS

■

Digital Calibration

■

Industrial Process Control

■

Automatic Test Equipment

■

Cellular Telephones

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

TYPICAL APPLICATION

Summary of content (12 pages)

PAGE 1
LTC1454/LTC1454L Dual 12-Bit Rail-to-Rail Micropower DACs U DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ The LTC®1454/LTC1454L are complete single supply, dual rail-to-rail voltage output, 12-bit digital-to-analog converters (DACs) in a 16-lead SO package. They include an output buffer amplifier with variable gain (×1 or × 2) and an easy-to-use 3-wire cascadable serial interface.
PAGE 2
LTC1454/LTC1454L W U U W W W VCC to GND .............................................. – 0.5V to 7.5V Logic Inputs to GND ................................ – 0.5V to 7.5V VOUT A , VOUT B, X1/X2 A , X1/X2 B ..................................... – 0.5V to VCC + 0.5V REFHI A , REFHI B, REFLO ............. – 0.5V to VCC + 0.5V Maximum Junction Temperature .......................... 125°C Operating Temperature Range LTC1454C/LTC1454LC ............................ 0°C to 70°C LTC1454I/LTC1454LI ..............
PAGE 3
LTC1454/LTC1454L ELECTRICAL CHARACTERISTICS VCC = 4.5V to 5.5V (LTC1454), 2.7V to 5.5V (LTC1454L), X1/X2 = REFLO = GND, REFHI = REFOUT, VOUT and REFOUT unloaded, TA = TMIN to TMAX, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS 5.5 5.5 V V Power Supply VCC Positive Supply Voltage For Specified Performance, LTC1454 LTC1454L ● ● 4.5 2.7 ICC Supply Current 4.5V ≤ VCC ≤ 5.5V (Note 4), LTC1454 2.7V ≤ VCC ≤ 5.
PAGE 4
LTC1454/LTC1454L U W TYPICAL PERFORMANCE CHARACTERISTICS LTC1454 Integral Nonlinearity 2.0 0.4 1.6 0.3 1.2 0.2 0.8 0.1 0 –0.1 –0.2 Minimum Supply Headroom for Full Output Swing vs Load Current 1.0 0.4 0 –0.4 –1.2 –0.4 –1.6 0 0 512 1024 1536 2048 2560 3072 3584 4095 CODE 3.5 –55°C 500 400 300 OUTPUT SWING (V) 600 3.0 2.5 2.0 RL 1.5 3.0 VCC 2.5 1.5 1.0 1.0 100 0.5 0.5 0.
PAGE 5
LTC1454/LTC1454L U U U PIN FUNCTIONS X1/X2 B, X1/X2 A (Pins 1, 7): For LTC1454, when this pin is grounded, the gain will be 2. When connected to VOUT the gain will be 1. In a gain of 2 configuration, the output full scale will be 2 × REFHI. When using the internal reference, this value is 4.096V. For the LTC1454L, when this pin is grounded, the gain will be 2.05. When connected to VOUT the gain will be 1. In a gain of 2 configuration, the output full scale will be 2.05 × REFHI.
PAGE 6
LTC1454/LTC1454L W BLOCK DIAGRA R R X1/X2 B 1 16 VOUT B CLR 2 15 VCC CLK 3 14 REFHI B 13 GND 12 REFLO 11 REFHI A 10 REFOUT 9 VCC – DIN CS/LD 5 DOUT 6 X1/X2 A LD 4 12-BIT DAC B REGISTER + DAC B 24-BIT SHIFT REGISTER LD 12-BIT DAC A REGISTER + DAC A A REFERENCE LTC1454: 2.048V LTC1454L: 1.
PAGE 7
LTC1454/LTC1454L U U DEFI ITIO S Resolution (n): Resolution is defined as the number of digital input bits, n. It defines the number of DAC output states (2n) that divide the full-scale range. The resolution does not imply linearity. Full-Scale Voltage (VFS): This is the output of the DAC when all bits are set to 1. Voltage Offset Error (VOS): The theoretical voltage at the output when the DAC is loaded with all zeros.
PAGE 8
LTC1454/LTC1454L U OPERATIO Serial Interface Reference The data on the DIN input is loaded into the shift register on the rising edge of the clock. Data is loaded as one 24-bit word, DAC A first, then DAC B. The MSB is loaded first for each DAC. The DAC registers load the data from the shift register when CS/LD is pulled high. The CLK is disabled internally when CS/LD is high. Note: CLK must be low before CS/LD is pulled low to avoid an extra internal clock pulse.
PAGE 9
LTC1454/LTC1454L U U W U APPLICATIONS INFORMATION ground of 1.22V. The outputs will swing from 0V to 2.44V, as shown by the equation with the figure. Since the signal ground is around 1.22V, REFLO is offset above ground by using an LT1034CS8-1.2 as shown. A Single Supply, 4-Quadrant Multiplying DAC The LTC1454 can also be used for 4-quadrant multiplying with an offset signal ground of 1.22V. This application is shown in Figure 2. The inputs are connected to REFHI B or REFHI A and have a 1.
PAGE 10
LTC1454/LTC1454L U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. N Package 16-Lead PDIP (Narrow 0.300) (LTC DWG # 05-08-1510) 0.770* (19.558) MAX 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 0.255 ± 0.015* (6.477 ± 0.381) 0.130 ± 0.005 (3.302 ± 0.127) 0.300 – 0.325 (7.620 – 8.255) 0.009 – 0.015 (0.229 – 0.381) ( +0.025 0.325 –0.015 +0.635 8.255 –0.381 ) 0.045 – 0.065 (1.143 – 1.651) 0.015 (0.381) MIN 0.065 (1.651) TYP 0.125 (3.175) MIN 0.005 (0.
PAGE 11
LTC1454/LTC1454L U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. S Package 16-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.386 – 0.394* (9.804 – 10.008) 16 15 14 13 12 11 10 9 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) 2 3 4 5 6 0.053 – 0.069 (1.346 – 1.752) 0.014 – 0.019 (0.355 – 0.483) 8 0.004 – 0.010 (0.101 – 0.254) 0° – 8° TYP 0.016 – 0.
PAGE 12
LTC1454/LTC1454L U TYPICAL APPLICATION LTC1454: 4.5V TO 5.5V LTC1454L: 2.7V TO 5.5V X1/X2 B µP TO NEXT DAC FOR DAISY-CHAINING OUTPUT A LTC1454: 0V TO 4.095V LTC1454L: 0V TO 2.5V VOUT B CLR VCC CLK REFHI B OUTPUT B LTC1454: 0V TO 4.095V LTC1454L: 0V TO 2.5V 0.1µF LTC1454 GND LTC1454L CS/LD REFLO DIN DOUT REFHI A X1/X2 A REFOUT VOUT A VCC LTC1454: 2.048V LTC1454L: 1.22V 1454 TA01 RELATED PARTS PART NUMBER LTC1257 LTC1446/LTC1446L DESCRIPTION Single 12-Bit VOUT DAC, Full Scale: 2.