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LTC2630

2630ff

Block Diagram

Features

applications

Description

Single 12-/10-/8-Bit

Rail-to- Rail DACs with 10ppm/°C

Reference in SC70

The LTC

2630 is a family of 12-, 10-, and 8-bit voltage-

output DACs with an integrated, high-accuracy, low-drift

reference in a 6-lead SC70 package. It has a rail-to-rail

output buffer and is guaranteed monotonic.

The LTC2630-L has a full-scale output of 2.5V, and

operates from a single 2.7V to 5.5V supply. The

LTC2630-H has a full-scale output of 4.096V, and operates

from a 4.5V to 5.5V supply. Each DAC can also operate in

supply as reference mode, which sets the full-scale output

to the supply voltage.

The parts use a simple SPI/MICROWIRE™ compatible

3-wire serial interface which operates at clock rates up

to 50MHz.

The LTC2630 incorporates a power-on reset circuit. Op-

tions are available for reset to zero or reset to mid-scale

after power-up.

L, LT, LTC, LTM , Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. All other trademarks are the property of their respective owners.

Protected by U.S. Patents, including 5396245, 5859606, 6891433, 6937178 and 7414561.

Integral Nonlinearity (LTC2630A-LZ12)

Integrated Precision Reference

2.5V Full Scale 10ppm/°C (LTC2630-L)

4.096V Full Scale 10ppm/°C (LTC2630-H)

Maximum INL Error: 1 LSB (LTC2630A-12)

Low Noise: 0.7mV

P-P

, 0.1Hz to 200kHz

Guaranteed Monotonic over Temperature

Selectable Internal Reference or Supply as Reference

2.7V to 5.5V Supply Range (LTC2630-L)

Low Power Operation: 180µA at 3V

Power Down to 1.8µA Maximum (C and I Grades)

Power-on Reset to Zero or Mid-Scale Options

SPI Serial Interface

Double-Buffered Data Latches

Tiny 6-Lead SC70 Package

Mobile Communications

Process Control and Industrial Automation

Automatic Test Equipment

Portable Equipment

Automotive

DAC

RESISTOR

DIVIDER

INTERNAL

REFERENCE

INPUT

24-BIT

SHIFT

DAC

OUT

CONTROL

DECODE LOGIC

CS/LD

GND

DACREF

2630 BD

SCK

SDI

CODE

INL (LSB)

0.5

4095

2630 TA03

–0.5

–1.0

1024

2048

3072

1.0

= 3V

= 2.5V

Summary of content (22 pages)

PAGE 1
LTC2630 Single 12-/10-/8-Bit Rail-to- Rail DACs with 10ppm/°C Reference in SC70 Description Features n n n n n n n n n n n n Integrated Precision Reference 2.5V Full Scale 10ppm/°C (LTC2630-L) 4.096V Full Scale 10ppm/°C (LTC2630-H) Maximum INL Error: 1 LSB (LTC2630A-12) Low Noise: 0.7mVP-P, 0.1Hz to 200kHz Guaranteed Monotonic over Temperature Selectable Internal Reference or Supply as Reference 2.7V to 5.5V Supply Range (LTC2630-L) Low Power Operation: 180µA at 3V Power Down to 1.
PAGE 2
LTC2630 Absolute Maximum Ratings (Notes 1, 2) Pin Configuration Supply Voltage (VCC).................................... –0.3V to 6V CS/LD, SCK, SDI........................................... –0.3V to 6V VOUT...................................–0.3V to min(VCC + 0.3V, 6V) Operating Temperature Range LTC2630C................................................. 0°C to 70°C LTC2630I..............................................–40°C to 85°C LTC2630H (Note 3).............................
PAGE 3
LTC2630 Product Selection Guide PART NUMBER LTC2630A-LM12 PART MARKING* VFS WITH INTERNAL REFERENCE LCZB 2.5V • (4095/4096) POWER-ON RESET TO CODE RESOLUTION VCC Mid-Scale 12-Bit 2.7V–5.5V MAXIMUM INL ±1LSB LTC2630A-LZ12 LCSB 2.5V • (4095/4096) Zero 12-Bit 2.7V–5.5V ±1LSB LTC2630A-HM12 LCWR 4.096V • (4095/4096) Mid-Scale 12-Bit 4.5V–5.5V ±1LSB LTC2630A-HZ12 LCZC 4.096V • (4095/4096) Zero 12-Bit 4.5V–5.5V ±1LSB LTC2630-LM12 LCZB 2.5V • (4095/4096) Mid-Scale 12-Bit 2.7V–5.
PAGE 4
LTC2630 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 2.7V to 5.5V, VOUT unloaded unless otherwise specified. LTC2630-LM12/-LM10/-LM8/-LZ12/-LZ10/-LZ8, LTC2630A-LM12/-LZ12 (VFS = 2.5V) LTC2630-8 SYMBOL PARAMETER CONDITIONS LTC2630-10 LTC2630-12 LTC2630A-12 MIN TYP MAX MIN TYP MAX MIN TYP MAX MIN TYP MAX UNITS DC Performance Resolution l 8 8 10 VCC = 3V, Internal Ref.
PAGE 5
LTC2630 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 2.7V to 5.5V, VOUT unloaded unless otherwise specified. LTC2630-LM12/-LM10/-LM8/-LZ12/-LZ10/-LZ8, LTC2630A-LM12/-LZ12 (VFS = 2.5V) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS AC Performance tS en Settling Time VCC = 3V (Note 9) ±0.39% (±1LSB at 8 Bits) ±0.098% (±1LSB at 10 Bits) ±0.024% (±1LSB at 12 Bits) 3.2 3.9 4.
PAGE 6
LTC2630 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 4.5V to 5.5V, VOUT unloaded unless otherwise specified. LTC2630-HM12/-HM10/-HM8/-HZ12/-HZ10/-HZ8, LTC2630A-HM12/-HZ12 (VFS = 4.096V) LTC2630-8 SYMBOL PARAMETER CONDITIONS LTC2630-10 LTC2630-12 LTC2630A-12 MIN TYP MAX MIN TYP MAX MIN TYP MAX MIN TYP MAX UNITS DC Performance l 8 10 12 12 Bits VCC = 5V, Internal Ref.
PAGE 7
LTC2630 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 4.5V to 5.5V, VOUT unloaded unless otherwise specified. LTC2630-HM12/-HM10/-HM8/-HZ12/-HZ10/-HZ8, LTC2630A-HM12/-HZ12 (VFS = 4.096V) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS AC Performance tS en Settling Time VCC = 5V (Note 9) ±0.39% (±1LSB at 8 Bits) ±0.098% (±1LSB at 10 Bits) ±0.024% (±1LSB at 12 Bits) 3.7 4.4 4.
PAGE 8
LTC2630 Typical Performance Characteristics LTC2630-LM12/-LZ12 (VFS = 2.5V) Integral Nonlinearity (INL) 1.0 Differential Nonlinearity (DNL) 1.0 VCC = 3V 0.5 DNL (LSB) INL (LSB) 0.5 0 –0.5 –1.0 VCC = 3V 0 –0.5 0 1024 2048 3072 –1.0 4095 0 2048 1024 CODE 3072 2630 G01 INL vs Temperature Full-Scale Output Voltage vs Temperature 1.0 VCC = 3V 2.52 VCC = 3V 0.5 INL (POS) 0 INL (NEG) –0.5 FS OUTPUT VOLTAGE (V) INL (LSB) 0.5 2630 G02 DNL vs Temperature DNL (POS) DNL (LSB) 1.
PAGE 9
LTC2630 Typical Performance Characteristics LTC2630-HM12/-HZ12 (VFS = 4.096V) Integral Nonlinearity (INL) 1.0 Differential Nonlinearity (DNL) 1.0 VCC = 5V 0.5 DNL (LSB) INL (LSB) 0.5 0 –0.5 –1.0 VCC = 5V 0 –0.5 0 1024 2048 3072 –1.0 4095 0 1024 CODE 2048 3072 2630 G08 INL vs Temperature Full-Scale Output Voltage vs Temperature 1.0 VCC = 5V 4.115 VCC = 5V 0.5 INL (POS) 0 INL (NEG) –0.5 FS OUTPUT VOLTAGE (V) INL (LSB) 0.
PAGE 10
LTC2630 Typical Performance Characteristics LTC2630-10 Integral Nonlinearity (INL) 1.0 Differential Nonlinearity (DNL) 1.0 VCC = 5V VFS = 4.096V 0.5 DNL (LSB) INL (LSB) 0.5 0 –0.5 –1.0 VCC = 5V VFS = 4.096V 0 –0.5 0 256 512 768 –1.0 1023 0 512 256 CODE 768 1023 CODE 2630 G15 2630 G16 LTC2630-8 Differential Nonlinearity (DNL) Integral Nonlinearity (INL) 1.0 0.50 VCC = 3V VFS = 2.5V 0.25 DNL (LSB) INL (LSB) 0.5 0 –0.5 –1.0 VCC = 3V VFS = 2.5V 0 –0.25 0 64 128 192 –0.
PAGE 11
LTC2630 Typical Performance Characteristics LTC2630 Power-On Reset Glitch Mid-Scale-Glitch Impulse Large-Signal Response LTC2630-L INTERNAL REF VCC 2V/DIV CS/LD 5V/DIV LTC2630-H12, VCC = 5V: 2.4nV-s TYP 0.5V/DIV VOUT 5mV/DIV ZERO-SCALE LTC2630-L12, VCC = 3V: 2.0nV-s TYP VFS = VCC = 5V 1/4 SCALE TO 3/4 SCALE 200µs/DIV 2µs/DIV 2µs/DIV Headroom at Rails vs Output Current Noise Voltage vs Frequency 500 5V SOURCING 4.5 NOISE VOLTAGE (nV/√Hz) 4.0 3V (LTC2630-L) SOURCING 2.5 2.0 1.
PAGE 12
LTC2630 Pin Functions CS/LD (Pin 1): Serial Interface Chip Select/Load Input. When CS/LD is low, SCK is enabled for shifting data on SDI into the register. When CS/LD is taken high, SCK is disabled and the specified command (see Table 1) is executed. VCC (Pin 4): Supply Voltage Input. 2.7V ≤ VCC ≤ 5.5V (LTC2630-L) or 4.5V ≤ VCC ≤ 5.5V (LTC2630-H). Also used as the reference input when the part is programmed to operate in supply as reference mode. Bypass to GND with a 0.1µF capacitor.
PAGE 13
LTC2630 Timing Diagram t1 t2 SCK t3 1 t6 t4 2 3 23 24 t10 SDI t5 t7 CS/LD 2630 F01 Figure 1. Serial Interface Timing Operation The LTC2630 is a family of single voltage output DACs in 6-lead SC70 packages. Each DAC can operate rail-to-rail referenced to the input supply, or with its full-scale voltage set by an integrated reference. Twelve combinations of accuracy (12-, 10-, and 8-bit), power-on reset value (zero or mid-scale), and full-scale voltage (2.5V or 4.096V) are available.
PAGE 14
LTC2630 OPERATION INPUT WORD (LTC2630-12) COMMAND C3 C2 C1 4 DON'T-CARE BITS C0 X X X X DATA (12 BITS + 4 DON'T-CARE BITS) D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 MSB D0 X X X X X X X X X X X X X X LSB INPUT WORD (LTC2630-10) COMMAND C3 C2 C1 4 DON'T-CARE BITS C0 X X X X DATA (10 BITS + 6 DON'T-CARE BITS) D9 D8 D7 D6 D5 D4 D3 D2 D1 MSB D0 X LSB INPUT WORD (LTC2630-8) COMMAND C3 C2 C1 4 DON'T-CARE BITS C0 X X X X DATA (8 BITS + 8 DON'T-CARE BITS) D7
PAGE 15
LTC2630 OPERATION The 16-bit data word is ignored for all commands that do not include a Write operation. Power-Down Mode For power-constrained applications, power-down mode can be used to reduce the supply current whenever the DAC output is not needed. When in power-down, the buffer amplifier, bias circuit, and reference circuit are disabled and draw essentially zero current. The DAC output is put into a high-impedance state, and the output pin is passively pulled to ground through a 200kΩ resistor.
PAGE 16
LTC2630 OPERATION Rail-to-Rail Output Considerations In any rail-to-rail voltage output device, the output is limited to voltages within the supply range. Since the analog output of the DAC cannot go below ground, it may limit for the lowest codes as shown in Figure 4b. Similarly, limiting can occur near full scale when using the supply as reference. If VFS = VCC and the DAC full-scale error (FSE) is positive, the output for the highest codes limits at VCC , as shown in Figure 4.
PAGE 17
LTC2630 OPERATION Optoisolated 4mA to 20mA Process Controller additional current through Q1. Note that at the maximum loop voltage of 80V, Q1 will dissipate 1.6W when IOUT = 20mA and must have an appropriate heat sink. Figure 5 shows how to use an LTC2630HZ to make an optoisolated, digitally-controlled 4mA to 20mA transmitter. The transmitter circuitry, including optoisolation, is powered by the loop voltage which has a wide range of 5.4V to 80V.
PAGE 18
NEGATIVE OFFSET 0V OUTPUT VOLTAGE (b) INPUT CODE 0 2,048 INPUT CODE (a) 4,095 Figure 4. Effects of Rail-to-Rail Operation on a DAC Transfer Curve (Shown for 12-Bits).
PAGE 19
LTC2630 Typical Application 12-Bit, 2.7V to 5.5V Single Supply, Voltage Output DAC 2.7V TO 5.5V SDI µP SCK CS/LD VCC LTC2630-LZ12 V OUT 0.1µF OUTPUT 0V TO 2.
PAGE 20
LTC2630 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. SC6 Package SC6 Package 6-Lead Plastic SC70 6-Lead Plastic SC70 Rev B) (Reference LTC DWG # 05-08-1638 (Reference LTC DWG # 05-08-1638 Rev B) 0.47 MAX 0.65 REF 1.80 – 2.20 (NOTE 4) 1.00 REF INDEX AREA (NOTE 6) 1.80 – 2.40 1.15 – 1.35 (NOTE 4) 2.8 BSC 1.8 REF PIN 1 RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.10 – 0.40 0.65 BSC 0.15 – 0.30 6 PLCS (NOTE 3) 0.80 – 1.
PAGE 21
LTC2630 Revision History (Revision history begins at Rev F) REV DATE DESCRIPTION F 06/12 Corrected units on parameter VOSTC from mV/°C to µV/°C PAGE NUMBER 6 2630ff Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
PAGE 22
LTC2630 Typical Application VLOOP 5.4V TO 80V ROFFSET 374k 0.1% LT3010-5 IN OUT + SHDN SENSE 1µF 1µF GND FROM OPTOISOLATED INPUTS SDI SCK VCC LTC2630-HZ VOUT RGAIN 76.8k 0.1% CS/LD + 1k LTC2054 3.01k – 10k 1000PF RS 10Ω 5V OPTO-ISOLATORS SDI SCK CS/LD 500Ω 10k 4N28 Q1 2N3440 IOUT SDI SCK CS/LD 2630 TA02 Figure 5.