Rainbow Electronics DS4426 User Manual

General Description

The DS4426 contains four I2C-adjustable current DACs
capable of sinking or sourcing current. External resis­tors set the full-scale range of each output. Each DAC
output has 127 sink and 127 source steps that are pro­grammed by the I2C interface. Power-supply tracking
functionality is provided for three channels using dedi­cated control inputs. Once power-supply tracking is
accomplished, the current outputs default to zero. Two
address pins allow up to four DS4426 devices to exist
on the same I2C bus.

Applications

Power-Supply Adjustment

Power-Supply Margining

Power-Supply Tracking

Adjustable Current Sink or Source

Features

♦ Four Current DACs

50µA to 200µA Adjustable Full-Scale Range
127 Settings Each for Sink and Source

♦ Power-Supply Tracking

Power-Supply Sequencing
Ramp-Up and Ramp-Down Tracking Control
Ratiometric Tracking Support

♦ +2.7V to +5.5V Operation

♦ I

2

C-Compatible Serial Interface

♦ Two Address Input Pins Allow Up to Four Devices

on Same I

2

C Bus

♦ Lead-Free, 28-Pin TQFN Package (4mm x 4mm)

with Exposed Pad

♦ Industrial Temperature Range: -40°C to +85°C

DS4426

Quad-Channel, I2C-Margining IDACs with

Three Channels of Power-Supply Tracking

________________________________________________________________

Maxim Integrated Products

1

Pin Configuration

Ordering Information

19-4541; Rev 1; 7/09

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

+

Denotes a lead(Pb)-free/RoHS-compliant package.

T&R = Tape and reel.

*

EP = Exposed pad.

PART TEMP RANGE PIN-PACKAGE

DS4426T+ -40°C to +85°C 28 TQFN-EP*

DS4426T+T&R -40°C to +85°C 28 TQFN-EP*

Functional Diagram appears at end of data sheet.

TOP VIEW

THR1

DNC

THR3

THR2

18

DS4426

*EP

4567

CC

V

OUT0

OUT1

INN3

OUT2

INP3

OUT3

14

INN2

INP2

13

12

INN1

INP1

11

10

A1

A0

9

8

GND

FS1

22

FS2

23

24

FS3

25

GAIN3

26

GAIN2

27

GAIN1

28

N.C.

*EXPOSED PAD.

FS0

2021 19 17 16 15

+

12

3

SCL

SDA

THIN QFN

(4mm × 4mm)

DS4426

Quad-Channel, I2C-Margining IDACs with
Three Channels of Power-Supply Tracking

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

RECOMMENDED OPERATING CONDITIONS

(TA= -40°C to +85°C.)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

Voltage Range on SDA, SCL Relative to GND ......-0.5V to +6.0V

Voltage Range on V

CC

Relative to GND ...............-0.5V to +6.0V

Voltage Range on A0, A1, FS[3:0], GAIN[3:1],

INN[3:1], INP[3:1], THR[3:1], and OUT[3:0]

Relative to GND ......................................-0.5V to (V

CC

+ 0.5V)*

Operating Temperature Range ...........................-40°C to +85°C

Storage Temperature Range .............................-55°C to +125°C

Soldering Temperature...........................Refer to the IPC/JEDEC

J-STD-020 Specification.

DC ELECTRICAL CHARACTERISTICS

(VCC= +2.7V to +5.5V, TA= -40°C to +85°C.)

DAC OUTPUT CURRENT CHARACTERISTICS

(VCC= +2.7V to +5.5V, TA= -40°C to +85°C.)

*

Not to exceed +6.0V.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Supply Voltage VCC (Note 1) 2.7 5.5 V

Input Logic 1
(SDA, SCL, A0, A1)

Input Logic 0
(SDA, SCL, A0, A1)

Full-Scale Resistor Values R

V

IH

V

-0.3

IL

(Note 2) 40 160 k

FS[3:0]

0.7 x
V

CC

VCC+

0.3

0.3 x
V

CC

V

V

PARAMETER S YMBOL CONDITIONS MIN TYP MAX UNITS

Supply Current ICC VCC = +5.5V (Note 3) 0.9 mA

Input Leakage Current
(SDA, SCL)

RFS Voltage V

Reference Voltage V

Temperature Coefficient ±100 ppm/°C

Output Leakage Current (SDA) IL -1 +1 μA

Output-Current Low (SDA) I

I/O Capacitance C

I

VCC = +5.5V -1 +1 μA

IL

TA = +25°C 0.940 0.990 1.040 V

RFS

REF

V

= +0.4V 3

OL

I/O

OL

V

= +0.6V 6

OL

10 pF

1.24 V

mA

PARAMETER S YMBOL CONDITIONS MIN TYP MAX UNITS

Output Current Variation Due to
Power-Supply Change

Output Current Variation Due to
Output-Voltage Change

DC source, V

DC sin k, V

DC source, VCC = +3.6V 0.15

DC sin k, V

measured at +1.2V 0.33

OUT

measured at +1.2V 0.33

OUT

= +3.6V 0.30

CC

%/V

%/V

DS4426

Quad-Channel, I2C-Margining IDACs with

Three Channels of Power-Supply Tracking

_______________________________________________________________________________________ 3

DAC OUTPUT CURRENT CHARACTERISTICS (continued)

(VCC= +2.7V to +5.5V, TA= -40°C to +85°C.)

I2C ELECTRICAL CHARACTERISTICS

(VCC= +2.7V to +5.5V, TA= -40°C to +85°C. Timing referenced to V

IL(MAX)

and V

IH(MIN)

. See Figure 6.)

PARAMETER S YMBOL CONDITIONS MIN TYP MAX UNITS

Output Voltage for Sinking
Current

Output Voltage for Sourcing
Current

Ful l-Scale Sink Output Current I

Ful l-Scale Source Output Current I

Output-Current Full-Scale
Accuracy

Output-Current Temperature
Coefficient

Output-Current Power-Supply
Rejection Ratio

Output-Leakage Current at Zero
Current Setting

Output-Current Differential
Linearity

Output-Current Integral Linearity INL (Note 7) 1 LSB

V

OUT:SINK

V

OUT:SOURCE

OUT:SINK

OUT:SOURCE

I

OUT:FS

I

OUT:TC

0.33 %/V

I

ZERO

DNL (Note 6) 0.5 LSB

(Note 4) 0.5 3.5 V

V

-

(Note 4) 0

(Note 4) 50 200 μA

(Note 4) -200 -50 μA

TA = +25°C ±5 %

(Note 5) ±130 ppm/°C

-1 +1 μA

CC

0.75

V

PARAMETER S YMBOL CONDITIONS MIN TYP MAX UNITS

SCL Clock Frequency f

Bus Free Time Between STOP
and START Condition s

Hold Time (Repeated) START
Condition

Low Period of SCL t

High Period of SCL t

Data Hold Time t

Data Setup Time t

START Setup Time t

SDA a nd SCL Rise Time tR (Note 9)

SDA and SCL Fall Time tF (Note 9)

STOP Setup Time t

SDA a nd SCL Capac it iv e
Loading

(Note 8) 0 400 kHz

SCL

t

1.3 μs

BUF

t

0.6 μs

HD: STA

1.3 μs

LOW

0.6 μs

HIGH

0 0.9 μs

HD:DAT

100 ns

SU:DAT

0.6 μs

SU:STA

0.6 μs

SU:STO

(Note 9) 400 pF

C

B

20 +

0.1C

20 +

0.1C

300 ns

B

300 ns

B

DS4426

Quad-Channel, I2C-Margining IDACs with
Three Channels of Power-Supply Tracking

4 _______________________________________________________________________________________

Note 1: All voltages are referenced to GND. Current entering the IC is specified positive, and current exiting the IC is negative.
Note 2: Input resistors (R

FS[3:0]

) must be between the specified values to ensure the device meets its accuracy and linearity specifi-

cations.

Note 3: Supply current specified with all outputs set to zero current setting and with all inputs at V

CC

or GND. SDA and SCL are

connected to V

CC

. Excludes current through RFSresistors (I

RFS

). Total current including I

RFS

is ICC+ (2 x I

RFS

).

Note 4: The output-voltage full-scale ranges must be satisfied to ensure the device meets its accuracy and linearity specifications.

Only applies to current DAC operation, not power-supply tracking operation.

Note 5: Temperature drift excludes drift caused by external resistors.
Note 6: Differential linearity is defined as the difference between the expected incremental current increase with respect to position

and the actual increase. The expected incremental increase is the full-scale range divided by 127.

Note 7: Integral linearity is defined as the difference between the expected value as a function of the setting and the actual value.

The expected value is a straight line between the zero and the full-scale values proportional to the setting.

Note 8: Timing shown is for fast-mode operation (400kHz). This device is also backward-compatible with I

2

C standard-mode timing.

Note 9: C

B

—Total capacitance of one bus line in pF.

POWER-SUPPLY TRACKING CHARACTERISTICS

(VCC= +2.7V to +5.5V, TA= -40°C to +85°C, see Figure 5.)

PARAMETER S YMBOL CONDITIONS MIN TYP MAX UNITS

Input Divider Ratio R

Output Load R

Feedback Resistor Ratio RF/R

Gain Resistor R

Gain Setting Ratio RL/R

Power-Supply Tracking Gain G

Power-Supply Tracking Input
Bias Current

Power-Supply Tracking Input
Voltage

Unity Gain Bandwidth GBW RL/RG= 1.4; RL= 5k 12 MHz

Output Voltage While Tracking V

Output Current While Track ing I

Tracking Accuracy ±600 mV

Output Leakage I

Comparator Input Bias Current I

Comparator Input Offset V

Swit ch Delay t

Comparator Hysteresis V

DIV

I

V

OUT:TRK

OUT:TRK

BC

OFF

DC

HYS

RA/RB and RC/RD 0.5 1

RL= (RF x RE)/(RF+RE) 1 20 k

L

0.5 4.5

B

0.8 10 k

G

1.4 5

G

RL/RG= 2, RL= 5k, VCC = +3.6V,
T

= +25°C

VI

B

IN

OS

A

RL/RG= 5, RL= 5k, VCC = +3.6V,

= +25°C

T

A

1 μA

INP[3:1] and INN[3:1] 0

Switch closed, VCC = +3.0V, measured at
OUT[3:1], R

RL/RG= 1.4, RG= 1k, V
V

= +0.8V

FB

Switch open 0.5 μA

1 μA

±5 mV

5 μs

12.5 mV

= 5k

L

= +3.0V,

CC

2.4

3.8 6.2 10

V

-

CC

1.4

0 1.5 V

1 mA

mA/V

V

DS4426

Quad-Channel, I2C-Margining IDACs with

Three Channels of Power-Supply Tracking

_______________________________________________________________________________________

5

Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

600

SDA = SCL = THR[3:1] = V
GAIN[3:1] = FS[3:0] = OUT[3:0] = OPEN

575

INP[3:1] = INN[3:1] = GND

550

525

500

475

SUPPLY CURRENT (μA)

450

425

400

2.5 5.5
SUPPLY VOLTAGE (V)

CC

5.04.53.0 3.5 4.0

VOLTCO (SINK)

250

40kΩ LOAD ON FS[3:0].

= +5.5V

V

CC

225

(μA)

200

OUT

I

175

SDA = SCL = THR[3:1] = V
GAIN[3:1] = OPEN
INP[3:1] = INN[3:1] = GND

150

0 4.0

CC

V

(V)

OUT

SUPPLY CURRENT

vs. TEMPERATURE

DS4426 toc01

600

575

550

525

500

475

SUPPLY CURRENT (μA)

450

425

400

VCC = +5.5V

SDA = SCL = THR[3:1] = V
GAIN[3:1] = FS[3:0] = OUT[3:0] = OPEN
INP[3:1] = INN[3:1] = GND

-40
TEMPERATURE (°C)

VCC = +3.3V

VCC = +2.7V

CC

8060-20 0 20 40

DS4426 toc02

-150

-175

(μA)

-200

OUT

I

-225

-250
05

TEMPERATURE COEFFICIENT

vs. SETTING (SOURCE)

DS4426 toc05

650

550

450

350

250

150

50

-50

TEMPERATURE COEFFICIENT (°C/ppm)

-150

-250
0

300

RANGE FOR THE 50μA TO 200μA
CURRENT SOURCE RANGE

250

DS4426 toc04

200

150

100

50

0

TEMPERATURE COEFFICIENT (°C/ppm)

3.53.02.52.01.51.00.5

-50
0

+25°C TO -40°C

+25°C TO +85°C

125100755025

SETTING (DEC)

VOLTCO (SOURCE)

40kΩ LOAD ON FS[3:0].

= +5.5V

V

CC

SDA = SCL = THR[3:1] = V
GAIN[3:1] = OPEN
INP[3:1] = INN[3:1] = GND

CC

V

(V)

OUT

TEMPERATURE COEFFICIENT

vs. SETTING (SINK)

RANGE FOR THE 50μA TO 200μA
CURRENT SINK RANGE

+25°C TO -40°C

+25°C TO +85°C

SETTING (DEC)

DS4426 toc03

4321

DS4426 toc06

125100755025

1.0

INTEGRAL LINEARITY

RANGE FOR THE 50μA TO 200μA

0.8
CURRENT SOURCE AND SINK RANGE

0.6

0.4

0.2

0

INL (LSB)

-0.2

-0.4

-0.6

-0.8

-1.0
0

SETTING (DEC)

125100755025

DS4426 toc07

1.0

0.8

0.6

0.4

0.2

0

DNL (LSB)

-0.2

-0.4

-0.6

-0.8

-1.0

DIFFERENTIAL LINEARITY

RANGE FOR THE 50μA TO 200μA
CURRENT SOURCE AND SINK RANGE

0

SETTING (DEC)

DS4426 toc08

125100755025