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LTC2634

2634fc

Block Diagram

Features

app

lications

Description

Quad 12-/10-/8-Bit

Rail-to-Rail DACs with

10ppm/°C Reference

The LTC

2634 is a family of quad 12-, 10- and 8-bit volt-

age output DACs with an integrated, high accuracy, low

drift 10ppm/°C reference in 16-lead QFN and 10-lead

MSOP packages. It has rail-to-rail output buffers and is

guaranteed monotonic. The LTC2634-L has a full-scale

output of 2.5V, and operates from a single 2.7V to 5.5V

supply. The LTC2634-H has a full-scale output of 4.096V,

and operates from a 4.5V to 5.5V supply. Each DAC can

also operate with an external reference, which sets the

full-scale output to the external reference voltage.

These DACs communicate via an SPI/MICROWIRE compat-

ible 3-wire serial interface which operates at clock rates

up to 50MHz. Serial data output (SDO), a hardware clear

(CLR), and an asynchronous DAC update (LDAC) capability

are available in the QFN package. The LTC2634 incorporates

a power-on reset circuit. Options are available for reset

to zero-scale or reset to mid-scale in internal reference

mode, or reset to mid-scale in external reference mode

after power-up.

Integral Nonlinearity

(LTC2634-LZ12)

Integrated Precision Reference

2.5V Full-Scale 10ppm/°C (LTC2634-L)

4.096V Full-Scale 10ppm/°C (LTC2634-H)

Maximum INL Error: ±2.5 LSB (LTC2634-12)

Low Noise: 0.75mV

P-P

0.1Hz to 200KHz

Guaranteed Monotonic over –40°C to 125°C

Temperature Range

Selectable Internal or External Reference

2.7V to 5.5V Supply Range (LTC2634-L)

Ultralow Crosstalk Between DACs (2.4nV•s)

Low Power: 0.6mA at 3V

Power-On Reset to Zero-Scale/Mid-Scale

Double Buffered Data Latches

Tiny 16-Lead 3mm × 3mm QFN and 10-Lead

MSOP Packages

Mobile Communications

Process Control and Industrial Automation

Automatic Test Equipment

Portable Equipment

Automotive

DAC A

OUTA

(REFLO)

CS/LD

SCK

( ) QFN PACKAGE ONLY

(LDAC)

GND

OUTB

REF

DAC D

DAC B DAC C

REF

OUTD

REF

OUTC

SWITCH

INTERNAL

REFERENCE

32-BIT SHIFT REGISTER

DECODE

CONTROL

LOGIC

POWER-ON

RESET

SDI

2634 BD

(SDO)

(CLR)

CODE

INL (LSB)

4095

2634 TA01

–1

–2

1024

2048

3072

= 3V

INTERNAL REF

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

ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property

of their respective owners. Protected by U.S. Patents including 5396245, 5859606, 6891433,

6937178, 7414561.

Summary of content (30 pages)

PAGE 1
LTC2634 Quad 12-/10-/8-Bit Rail-to-Rail DACs with 10ppm/°C Reference Features Description Integrated Precision Reference 2.5V Full-Scale 10ppm/°C (LTC2634-L) 4.096V Full-Scale 10ppm/°C (LTC2634-H) n Maximum INL Error: ±2.5 LSB (LTC2634-12) n Low Noise: 0.75mV P-P 0.1Hz to 200KHz n Guaranteed Monotonic over –40°C to 125°C Temperature Range n Selectable Internal or External Reference n 2.7V to 5.5V Supply Range (LTC2634-L) n Ultralow Crosstalk Between DACs (2.4nV•s) n Low Power: 0.
PAGE 2
LTC2634 Absolute Maximum Ratings (Notes 1, 2) Supply Voltage (VCC).................................... –0.3V to 6V CS/LD, SCK, SDI, LDAC, CLR, SDO, REFLO.. –0.3V to 6V VOUTA-VOUTD..................... –0.3V to Min (VCC + 0.3V, 6V) REF................................... –0.3V to Min (VCC + 0.3V, 6V) Operating Temperature Range LTC2634C................................................. 0°C to 70°C LTC2634I.............................................. –40°C to 85°C LTC2634H (Note 3)............................
PAGE 3
LTC2634 Order Information LTC2634 C UD -L Z 12 #TR PBF LEAD FREE DESIGNATOR PBF = Lead Free TAPE AND REEL TR = 2,500-Piece Tape and Reel RESOLUTION 12 = 12-Bit 10 = 10-Bit 8 = 8-Bit POWER-ON RESET MI = Reset to Mid-Scale in Internal Reference Mode MX = Reset to Mid-Scale in External Reference Mode Z = Reset to Zero-Scale in Internal Reference Mode FULL-SCALE VOLTAGE, INTERNAL REFERENCE MODE L = 2.5V H = 4.
PAGE 4
LTC2634 Product Selection Guide PART MARKING* VFS WITH INTERNAL POWER-ON REFERENCE RESET TO CODE POWER-ON REFERENCE MODE PART NUMBER QFN MSOP RESOLUTION VCC MAXIMUM INL LTC2634-LMI12 LTC2634-LMI10 LTC2634-LMI8 LDQX LDRF LDRN LTDRV LTDSC LTDSK 2.5V • (4095/4096) 2.5V • (1023/1024) 2.5V • (255/256) Mid-Scale Mid-Scale Mid-Scale Internal Internal Internal 12-Bit 10-Bit 8-Bit 2.7V to 5.5V 2.7V to 5.5V 2.7V to 5.5V ±2.5LSB ±1LSB ±0.
PAGE 5
LTC2634 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. LTC2634-LMI12/-LMI10/-LMI8/-LMX12/-LMX10/-LMX8/-LZ12/-LZ10/-LZ8 (VFS = 2.5V) SYMBOL PARAMETER LTC2634-8 LTC2634-10 LTC2634-12 MIN TYP MAX MIN TYP MAX MIN TYP MAX CONDITIONS UNITS DC Performance Resolution l 8 8 10 12 10 Bits Monotonicity VCC = 3V, Internal Ref.
PAGE 6
LTC2634 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. LTC2634-LMI12/-LMI10/-LMI8/-LMX12/-LMX10/-LMX8/-LZ12/-LZ10/-LZ8 (VFS = 2.5V) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VCC V 160 200 kΩ 0.005 1.5 µA 1.25 1.
PAGE 7
LTC2634 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. LTC2634-LMI12/-LMI10/-LMI8/-LMX12/-LMX10/-LMX8/-LZ12/-LZ10/-LZ8 (VFS = 2.
PAGE 8
LTC2634 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. LTC2634-HMI12/-HMI10/-HMI8/-HMX12/-HMX10/-HMX8/-HZ12/-HZ10/-HZ8 (VFS = 4.096V) SYMBOL PARAMETER LTC2634-8 LTC2634-10 LTC2634-12 MIN TYP MAX MIN TYP MAX MIN TYP MAX CONDITIONS UNITS DC Performance Resolution DNL l 8 8 10 Monotonicity VCC = 5V, Internal Ref.
PAGE 9
LTC2634 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. LTC2634-HMI12/-HMI10/-HMI8/-HMX12/-HMX10/-HMX8/-HZ12/-HZ10/-HZ8 (VFS = 4.096V) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VCC V 200 kΩ 0.005 1.5 µA 2.048 2.
PAGE 10
LTC2634 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. LTC2634-HMI12/-HMI10/-HMI8/-HMX12/-HMX10/-HMX8/-HZ12/-HZ10/-HZ8 (VFS = 4.
PAGE 11
LTC2634 Typical Performance Characteristics TA = 25°C, unless otherwise noted. LTC2634-L12 (Internal Reference, 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 CODE 3072 –1.0 4095 1024 0 2048 CODE 3072 2634 G01 INL vs Temperature 1.0 DNL (LSB) INL (LSB) 0 –1.0 –50 –25 25 50 75 100 125 150 TEMPERATURE (°C) DNL (POS) 0 DNL (NEG) 1.250 1.245 –1.
PAGE 12
LTC2634 Typical Performance Characteristics TA = 25°C, unless otherwise noted. LTC2634-H12 (Internal Reference, 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 CODE 3072 –1.0 4095 0 1024 2048 CODE 3072 2634 G08 INL vs Temperature 1.0 VCC = 5V INL (POS) 2.068 VCC = 5V 0.5 0 INL (NEG) –0.5 –1.0 –50 –25 Reference Output Voltage vs Temperature DNL (POS) 0 DNL (NEG) –0.
PAGE 13
LTC2634 Typical Performance Characteristics TA = 25°C, unless otherwise noted LTC2634-10 Integral Nonlinearity (INL) 1.0 Differential Nonlinearity (DNL) 1.0 VCC = 3V VFS = 2.5V INTERNAL REF 0.5 DNL (LSB) INL (LSB) 0.5 0 –0.5 –1.0 VCC = 3V VFS = 2.5V INTERNAL REF 0 –0.5 256 0 512 CODE 768 –1.0 1023 256 0 512 CODE 768 2634 G15 1023 2634 G16 LTC2634-8 Integral Nonlinearity (INL) 0.50 Differential Nonlinearity (DNL) 0.50 VCC = 3V VFS = 2.5V INTERNAL REF 0.25 DNL (LSB) INL (LSB) 0.
PAGE 14
LTC2634 Typical Performance Characteristics TA = 25°C, unless otherwise noted LTC2634 Large-Signal Response Mid-Scale Glitch Impulse Power-On Reset Glitch LTC2634-L VCC 2V/DIV CS/LD 5V/DIV VOUT 0.5V/DIV LTC2634-H12, VCC = 5V 3.0nV•s TYP ZERO SCALE VOUT 5mV/DIV VOUT 5mV/DIV LTC2634-L12, VCC = 3V 2.1nV•s TYP VFS = VCC = 5V 1/4 SCALE to 3/4 SCALE 2µs/DIV 2µs/DIV 2634 G22 Headroom at Rails vs Output Current VCC = 5V INTERNAL REF 4.
PAGE 15
LTC2634 Typical Performance Characteristics TA = 25°C, unless otherwise noted LTC2634 Noise Voltage vs Frequency 500 0 NOISE VOLTAGE (nV/√Hz) –2 –4 –8 –10 –12 VCC = 5V VREF(DC) = 2V VREF(AC) = 0.2VP-P CODE = FULL-SCALE –14 –16 –18 1k 10k 100k FREQUENCY (Hz) VCC = 5V CODE = MID-SCALE INTERNAL REF VCC = 5.5V 0.8 GAIN ERROR OF 4 CHANNELS 0.6 300 LTC2634-H 200 LTC2634-L 100 0.4 0.2 0 –0.2 –0.4 –0.6 –0.8 1M 0 100 2636 G31 1k 10k 100k FREQUENCY (Hz) –1.0 1M 1 1.5 2 2.5 3 3.5 4 4.
PAGE 16
LTC2634 Pin Functions (QFN/MSOP) VOUTA to VOUTD (Pins 1-2, 11-12/Pins 2-3, 8-9): DAC Analog Voltage Outputs. LDAC (Pin 3, QFN Only): Asynchronous DAC Update Pin. If CS/LD is high, a falling edge on LDAC immediately updates the DAC registers with the contents of the input registers (similar to a software update). If CS/LD is low when LDAC goes low, the DAC registers are updated after CS/LD returns high. A low on the LDAC pin powers up the DACs. A software power-down command is ignored if LDAC is low.
PAGE 17
LTC2634 Block Diagram INTERNAL REFERENCE GND SWITCH REF VREF VCC REGISTER REGISTER DAC A REGISTER VOUTA REGISTER (REFLO) DAC D VREF REGISTER REGISTER REGISTER DAC B REGISTER VREF VOUTB VOUTD DAC C SDI CS/LD CONTROL LOGIC SCK (LDAC) VOUTC DECODE 32-BIT SHIFT REGISTER POWER-ON RESET (CLR) (SDO) 2634 BD ( ) QFN PACKAGE ONLY 2634fc 17
PAGE 18
LTC2634 Timing Diagrams t1 t2 SCK t3 1 t6 t4 2 3 23 24 t10 SDI t5 t7 CS/LD t12 SDO t11 t9 LDAC 2634 F01a Figure 1a CS/LD t11 LDAC 2634 F01b Figure 1b 2634fc 18
PAGE 19
LTC2634 Operation The LTC2634 is a family of quad voltage output DACs in 16-lead QFN and 10-lead MSOP packages. Each DAC can operate rail-to-rail using an external reference, or with its full-scale voltage set by an integrated reference. Eighteen combinations of accuracy (12-, 10- and 8-bit), power-on reset value (zero-scale, mid-scale in internal reference mode, or mid-scale in external reference mode), and fullscale voltage (2.5V or 4.096V) are available.
PAGE 20
LTC2634 Operation of CS/LD. The rising edge of CS/LD ends the data transfer and causes the device to execute the command specified in the 24-bit input sequence. The complete sequence is shown in Figure 3a. The command (C3-C0) and address (A3-A0) assignments are shown in Tables 1 and 2. The first four commands in Table 1 consist of write and update operation. A write operation loads a 16-bit data word from the 24-bit shift register into the input register of the selected DAC, n.
PAGE 21
LTC2634 Operation While the minimum input sequence is 24 bits, it may optionally be extended to 32 bits to accommodate microprocessors that have a minimum word width of 16 bits (2 bytes). To use the 32-bit width, 8 don’t care bits must be transferred to the device first, followed by the 24-bit sequence described. Figure 3b shows the 32‑bit sequence. The 16-bit data word is ignored for all commands that do not include a write operation.
PAGE 22
LTC2634 Operation Power-Down Mode For power-constrained applications, power-down mode can be used to reduce the supply current whenever less than four DAC outputs are needed. When in power down, the buffer amplifiers, bias circuits, and integrated reference circuits are disabled, and draw essentially zero current. The DAC outputs are put into a high impedance state, and the output pins are passively pulled to ground through individual 200k resistors.
PAGE 23
LTC2634 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 the REF pin is tied to VCC. If VREF = VCC and the DAC full-scale error (FSE) is positive, the output for the highest codes limits at VCC, as shown in Figure 4c.
PAGE 24
X X SDI SDO SCK CS/LD 1 X X 2 X X 3 X 4 X X DON’T CARE X 5 C3 SDI C2 2 C1 3 X X 6 X X 7 4 7 A1 ADDRESS A2 6 A0 8 D11 9 D10 10 D9 D8 12 D7 13 D6 14 24-BIT INPUT WORD 11 D5 15 D3 17 DATA WORD D4 16 D2 18 D1 C3 C3 C2 10 C1 11 C2 C1 COMMAND WORD 9 C0 C0 A3 A3 A2 14 A1 15 A2 A1 ADDRESS WORD 13 A0 A0 16 17 D11 D11 PREVIOUS 32-BIT INPUT WORD 12 D10 D10 18 t2 t4 t12 D5 D5 23 PREVIOUS D11 t3 17 D6 D6 22 SDO t1 D7 D7 21
PAGE 25
LTC2634 Operation POSITIVE FSE VREF = VCC VREF = VCC OUTPUT VOLTAGE OUTPUT VOLTAGE INPUT CODE 0V NEGATIVE OFFSET 2634 F04 (4c) OUTPUT VOLTAGE 0 2,048 INPUT CODE 4,095 (4a) 0V INPUT CODE (4b) Figure 4.
PAGE 26
0.1µF 7 + 6 5 LT1634-1.25 30k –15V – OUTC –15V 4 1/2 LT1469 8 + – 0.1µF VDD 62 REFA DAC C DAC D 63 RCOM1 64 RIN1 61 ROFSA 15 IOUT1A 59 RFBA 60 GND 19 RVOSA 58 IOUT2A 2 DAC B DAC A LTC2755 + – 0.1µF 8 15V 30k OUTB LT1634-1.25 –15V 4 1/2 LT1469 –15V 3 2 + 5V – 15V 0.1µF OUTA 30k SERIAL BUS LT1634-1.25 –15V 0.1µF 1 0.
PAGE 27
LTC2634 Package Description UD Package 16-Lead Plastic QFN (3mm × 3mm) (Reference LTC DWG # 05-08-1691) 0.70 p0.05 3.50 p 0.05 1.45 p 0.05 2.10 p 0.05 (4 SIDES) PACKAGE OUTLINE 0.25 p0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 p 0.10 (4 SIDES) BOTTOM VIEW—EXPOSED PAD PIN 1 NOTCH R = 0.20 TYP OR 0.25 s 45o CHAMFER R = 0.115 TYP 0.75 p 0.05 15 PIN 1 TOP MARK (NOTE 6) 16 0.40 p 0.10 1 1.45 p 0.10 (4-SIDES) 2 (UD16) QFN 0904 0.200 REF 0.00 – 0.05 NOTE: 1.
PAGE 28
LTC2634 Package Description MSE Package 10-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1664 Rev D) BOTTOM VIEW OF EXPOSED PAD OPTION 1.88 p 0.102 (.074 p .004) 5.23 (.206) MIN 0.889 p 0.127 (.035 p .005) 1.68 p 0.102 (.066 p .004) 1 0.05 REF 10 3.00 p 0.102 (.118 p .004) (NOTE 3) DETAIL “B” CORNER TAIL IS PART OF DETAIL “B” THE LEADFRAME FEATURE. FOR REFERENCE ONLY NO MEASUREMENT PURPOSE 10 9 8 7 6 DETAIL “A” 0o – 6o TYP 1 2 3 4 5 GAUGE PLANE 0.53 p 0.152 (.021 p .
PAGE 29
LTC2634 Revision History REV DATE DESCRIPTION PAGE NUMBER A 10/09 Changes to Electrical Characteristics maximum limits B 12/09 Change pin name to DNC C 06/10 5, 6, 8, 9 2, 16 Revised Note 3 in the Electrical Characteristics section 10 Added Typical Application and replaced Related Parts list 30 2634fc Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use.
PAGE 30
LTC2634 typical application LTC2634 DACs Adjusts LTC2755-16 Offsets, Amplified with LT1991 PGA to ±5V 5V 15V 0.1µF 0.1µF 7 8 + 1/2 LT1469 – 4 0.1µF 15 VDD 5 RFBA 60 64 RIN1 2 IOUT1A 59 63 RCOM1 6 DAC A IOUT2A 2 – 3 RVOSA 58 –15V + 15V LTC2755 61 ROFSA 8 1/2 LT1469 + 0.1µF – 1 –15V 15V OUTA 4 62 REFA LTC6240 5V 7 0.1µF 0.1µF REF 2 LTC2634MSE-LMI12 DAC A DAC D DAC B DAC C VCC 1 0.1µF 9 LT1634-1.25 DAC D 30k 3 LT1634-1.25 –15V LT1634-1.