Linear Technology LTC1661 Datasheet

FEATURES

LTC1661

Micropower Dual

10-Bit DAC in MSOP

U

DESCRIPTIO

■

Tiny: Two 10-Bit DACs in an 8-Lead MSOP—
Half the Board Space of an SO-8

■

Micropower: 60µA per DAC
Sleep Mode: 1µA for Extended Battery Life

■

Rail-to-Rail Voltage Outputs Drive 1000pF

■

Wide 2.7V to 5.5V Supply Range

■

Double Buffered for Independent or Simultaneous
DAC Updates

■

Reference Range Includes Supply for Ratiometric
0V-to-VCC Output

■

Reference Input Has Constant Impedance over All
Codes (260kΩ Typ)—Eliminates External Buffers

■

3-Wire Serial Interface with
Schmitt Trigger Inputs

■

Differential Nonlinearity: ≤±0.75LSB Max

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APPLICATIO S

■

Mobile Communications

■

Digitally Controlled Amplifiers and Attenuators

■

Portable Battery-Powered Instruments

■

Automatic Calibration for Manufacturing

■

Remote Industrial Devices

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

The LTC®1661 integrates two accurate, serially addres­sable, 10-bit digital-to-analog converters (DACs) in a
single tiny MS8 package. Each buffered DAC draws just
60µA total supply current, yet is capable of supplying DC
output currents in excess of 5mA and reliably driving
capacitive loads up to 1000pF. Sleep mode further re­duces total supply current to a negligible 1µA.

Linear Technology’s proprietary, inherently monotonic
voltage interpolation architecture provides excellent lin­earity while allowing for an exceptionally small external
form factor. The double-buffered input logic provides
simultaneous update capability and can be used to write to
either DAC without interrupting Sleep mode.

Ultralow supply current, power-saving Sleep mode and
extremely compact size make the LTC1661 ideal for
battery-powered applications, while its straightforward
usability, high performance and wide supply range make
it an excellent choice as a general purpose converter.

For additional outputs and even greater board density,
please refer to the LTC1660 micropower octal DAC for
10-bit applications. For 8-bit applications, please consult
the LTC1665 micropower octal DAC.

W

BLOCK DIAGRA

V

OUT A

GND

8 5

7

10-BIT
DAC A

1 4

CS/LD

LATCH

CONTROL

LOGIC

2

SCK

LATCH

SHIFT REGISTER

LATCH

ADDRESS
DECODER

LATCH

V

10-BIT
DAC B

D

V

CC

6

3

OUT B

REF

IN

1661 BD

Differential Nonlinearity (DNL)

0.75

0.60

0.40

0.20

0

LSB

–0.20

–0.40
–0.60

–0.75

0 256 512 768 1023

CODE

1661 G02

1

LTC1661

1
2
3
4

8
7
6
5

TOP VIEW

CS/LD

SCK

D

IN

REF

V

OUT A

GND
V

CC

V

OUT B

N8 PACKAGE

8-LEAD PLASTIC DIP

A

W

O

LUTEXI TIS

S

A

WUW

U

ARB

G

(Note 1)

VCC to GND.............................................. –0.3V to 7.5V

Logic Inputs to GND ................................ –0.3V to 7.5V

V

OUT A

, V

, REF to GND............–0.3V to VCC + 0.3V

OUT B

Maximum Junction Temperature......................... 125°C

Storage Temperature Range................ –65°C to 150°C

WU

/

PACKAGE

CS/LD

SCK

D

IN

REF

8-LEAD PLASTIC MSOP

T

JMAX

Consult factory for Military grade parts.

O

RDER I FOR ATIO

TOP VIEW

1
2
3
4

MS8 PACKAGE

= 125°C, θJA = 150°C/W

ORDER PART

NUMBER

8

V

OUT A

7

GND

6

V

CC

V

5

OUT B

LTC1661CMS8
LTC1661IMS8

MS8 PART MARKING

LTDV
LTDW

Operating Temperature Range

LTC1661C ............................................. 0°C to 70°C

LTC1661I........................................... –40°C to 85°C

Lead Temperature (Soldering, 10 sec)................ 300°C

U

ORDER PART

NUMBER

LTC1661CN8
LTC1661IN8

T

= 125°C, θJA = 100°C/W

JMAX

LECTRICAL C CHARA TERIST

E

ICS

temperature range, otherwise specifications are at TA = 25°C. VCC = 2.7V to 5.5V, V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Accuracy

Resolution ● 10 Bits

Monotonicity 1V ≤ V
DNL Differential Nonlinearity 1V ≤ V
INL Integral Nonlinearity 1V ≤ V
V

OS

FSE Full-Scale Error VCC = 5V, V

PSR Power Supply Rejection V

Reference Input

I

REF

Power Supply

V

CC

I

CC

2

Offset Error Measured at Code 20 ● ±5 ±30 mV

VOS Temperature Coefficient ±15 µV/°C

Full-Scale Error Temperature Coefficient ±30 µV/°C

Input Voltage Range ● 0V

Resistance Active Mode ● 140 260 kΩ

Capacitance ● 15 pF

Reference Current Sleep Mode ● 0.001 1 µA

Positive Supply Voltage For Specified Performance ● 2.7 5.5 V

Supply Current VCC = 5V (Note 3) ● 120 195 µA

The ● denotes the specifications which apply over the full operating

≤ VCC, V

REF

≤ VCC – 0.1V (Note 2) ● 10 Bits

REF

≤ VCC – 0.1V (Note 2) ● ±0.1 ±0.75 LSB

REF

≤ VCC – 0.1V (Note 2) ● ±0.4 ±2 LSB

REF

= 4.096V ● ±1 ±12 LSB

REF

= 2.5V 0.18 LSB/V

REF

= 3V (Note 3) ● 95 154 µA

V

CC

Sleep Mode (Note 3)

Unloaded unless otherwise noted.

OUT

CC

● 13µA

V

LTC1661

LECTRICAL C CHARA TERIST

E

ICS

temperature range, otherwise specifications are at TA = 25°C. VCC = 2.7V to 5.5V, V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
DC Performance

Short-Circuit Current Low V

Short-Circuit Current High V

AC Performance

Voltage Output Slew Rate Rising (Notes 4, 5) 0.60 V/µs

Voltage Output Settling Time To ±0.5LSB (Notes 4, 5) 30 µs

Capacitive Load Driving 1000 pF

Digital I/O

V

IH

V

IL

I

LK

C

IN

Digital Input High Voltage VCC = 2.7V to 5.5V ● 2.4 V

Digital Input Low Voltage VCC = 4.5V to 5.5V ● 0.8 V

Digital Input Leakage VIN = GND to V

Digital Input Capacitance (Note 6) ● 10 pF

The ● denotes the specifications which apply over the full operating

≤ VCC, V

REF

= 0V, VCC = V

OUT

= VCC = V

OUT

Falling (Notes 4, 5) 0.25 V/µs

= 2.7V to 3.6V ● 2.0 V

V

CC

= 2.7V to 5.5V ● 0.6 V

V

CC

= 5V, Code = 1023 ● 10 25 100 mA

REF

= 5V, Code = 0 ● 7 19 120 mA

REF

CC

Unloaded unless otherwise noted.

OUT

● ±10 µA

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TI I G CHARACTERISTICS

range, otherwise specifications are at TA = 25°C.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VCC = 4.5V to 5.5V

t

1

t

2

t

3

t

4

t

5

t

6

t

7

t

9

t

11

VCC = 2.7V to 5.5V

t

1

t

2

t

3

t

4

t

5

t

6

t

7

t

9

t

11

DIN Valid to SCK Setup ● 40 15 ns

DIN Valid to SCK Hold ● 0–10 ns

SCK High Time (Note 6) ● 30 14 ns

SCK Low Time (Note 6) ● 30 14 ns

CS/LD Pulse Width (Note 6) ● 80 27 ns

LSB SCK High to CS/LD High (Note 6) ● 30 2 ns

CS/LD Low to SCK High (Note 6) ● 20 –21 ns

SCK Low to CS/LD Low (Note 6) ● 0–5 ns

CS/LD High to SCK Positive Edge (Note 6) ● 20 0 ns

SCK Frequency Square Wave (Note 6) ● 16.7 MHz

DIN Valid to SCK Setup (Note 6) ● 60 20 ns

DIN Valid to SCK Hold (Note 6) ● 0–10 ns

SCK High Time (Note 6) ● 50 15 ns

SCK Low Time (Note 6) ● 50 15 ns

CS/LD Pulse Width (Note 6) ● 100 30 ns

LSB SCK High to CS/LD High (Note 6) ● 50 3 ns

CS/LD Low to SCK High (Note 6) ● 30 –14 ns

SCK Low to CS/LD Low (Note 6) ● 0–5 ns

CS/LD High to SCK Positive Edge (Note 6) ● 30 0 ns

SCK Frequency Square Wave (Note 6) ● 10 MHz

The ● denotes the specifications which apply over the full operating temperature

Note 1: Absolute maximum ratings are those values beyond which the life

of a device may be impaired.

Note 2: Nonlinearity and monotonicity are defined from code 20 to code
1023 (full scale). See Applications Information.

3

LTC1661

UW

TI I G CHARACTERISTICS

Note 3: Digital inputs at 0V or VCC.
Note 4: Load is 10kΩ in parallel with 100pF.

Note 5: VCC = V

i.e., codes k = 102 and k = 922.
Note 6: Guaranteed by design and not subject to test.

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TYPICAL PERFOR A CE CHARACTERISTICS

Integral Nonlinearity (INL) Differential Nonlinearity (DNL)

2.0

1.5

1.0

0.5
0

LSB

–0.5
–1.0
–1.5
–2.0

0 256 512 768 1023

CODE

1661 G01

0.75

0.60

0.40

0.20

0

LSB

–0.20

–0.40
–0.60

–0.75

0 256 512 768 1023

CODE

= 5V. DAC switched between 0.1VFS and 0.9VFS,

REF

Minimum Supply Headroom vs
Load Current (Output Sourcing)

1400

V

= 4.096V

REF

1661 G02

1200

1000

(mV)

OUT

– V

CC

V

800

600

400

200

0

< 1LSB

∆V

OUT

CODE = 1023

0246810

|

I

|

(mA) (Sourcing)

OUT

125°C

25°C

–55°C

1661 G03

Minimum V

OUT

vs

Load Current (Output Sinking)

1400

VCC = 5V

1200

CODE = 0

1000

800

(mV)

OUT

600

V

400

200

0

0246810

|

I

|

(mA) (Sinking)

OUT

125°C

25°C

–55°C

1661 G04

Midscale Output Voltage vs
Load Current

3

V

= V

REF

2.9

2.8

2.7

2.6

(V)

2.5

OUT

V

2.4

2.3

2.2

2.1
2

–30 –20 –10 0 10 20 30

CC

CODE = 512

VCC = 5.5V

VCC = 5V

VCC = 4.5V

I

(mA)

OUT

SINKSOURCE

1661 G05

Midscale Output Voltage vs
Load Current

2

V

= V

REF

1.9

1.8

1.7

1.6

(V)

1.5

OUT

V

1.4

1.3

1.2

1.1
1

–15 –4–8–12 0 4 8 12 15

CC

CODE = 512

VCC = 3.6V

VCC = 3V

VCC = 2.7V

I

OUT

SINKSOURCE

(mA)

1661 G06

4