Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsData collecting ICsData acquisition IC - DA converter (DAC) TQFN 28

General Description

The DS4426 contains four I

C-adjustable current DACs

capable of sinking or sourcing current. External resis-

tors set the full-scale range of each output. Each DAC

output has 127 sink and 127 source steps that are pro-

grammed by the I

C interface. Power-supply tracking

functionality is provided for three channels using dedi-

cated 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 I

C 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

C-Compatible Serial Interface

♦ Two Address Input Pins Allow Up to Four Devices

on Same I

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, I

C-Margining IDACs with

Three Channels of Power-Supply Tracking

________________________________________________________________

Maxim Integrated Products

SCL

OUT0

OUT1

OUT2

OUT3

SDA

THR1

DNC

THR3

FS0

INN3

INP3

GAIN3

4567

2021 19 17 16 15

GAIN2

GAIN1

INN1

INP1

THR2

N.C.

GND

FS3

INP2

FS2

INN2

FS1

THIN QFN

(4mm

4mm)

TOP VIEW

DS4426

*EP

*EXPOSED PAD.

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.

Summary of content (15 pages)

PAGE 1
9-4541; Rev 1; 7/09 Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking 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.
PAGE 2
DS4426 Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking ABSOLUTE MAXIMUM RATINGS 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. Voltage Range on SDA, SCL Relative to GND ......-0.5V to +6.0V Voltage Range on VCC Relative to GND ...............-0.5V to +6.
PAGE 3
Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking (VCC = +2.7V to +5.5V, TA = -40°C to +85°C.) PARAMETER Output Voltage for Sinking Current Output Voltage for Sourcing Current Full-Scale Sink Output Current Full-Scale Source Output Current SYMBOL VOUT:SINK CONDITIONS (Note 4) VOUT:SOURCE (Note 4) IOUT:SINK (Note 4) IOUT:SOURCE (Note 4) Output-Current Full-Scale Accuracy I OUT:FS TA = +25°C Output-Current Temperature Coefficient I OUT:TC (Note 5) MIN MAX UNITS 0.
PAGE 4
DS4426 Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking POWER-SUPPLY TRACKING CHARACTERISTICS (VCC = +2.7V to +5.5V, TA = -40°C to +85°C, see Figure 5.) PARAMETER Input Divider Ratio Output Load Feedback Resistor Ratio Gain Resistor Gain Setting Ratio Power-Supply Tracking Gain SYMBOL RDIV MIN TYP MAX 0.5 1 1 20 RF/RB 0.5 4.5 RG 0.8 10 RL/RG 1.
PAGE 5
Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking 525 500 475 450 40kΩ LOAD ON FS[3:0]. VCC = +5.5V VCC = +3.3V 550 -175 525 500 VCC = +2.7V -225 SDA = SCL = THR[3:1] = VCC GAIN[3:1] = OPEN INP[3:1] = INN[3:1] = GND SDA = SCL = THR[3:1] = VCC GAIN[3:1] = FS[3:0] = OUT[3:0] = OPEN INP[3:1] = INN[3:1] = GND 425 400 -250 400 3.0 3.5 4.0 4.5 5.0 5.5 -40 -20 0 20 40 60 0 80 3 4 VOUT (V) VOLTCO (SINK) TEMPERATURE COEFFICIENT vs.
PAGE 6
Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking DS4426 Pin Description PIN NAME 1 SDA Serial Data Input/Output. I2C data pin. FUNCTION 2 SCL Serial Clock Input. I2C clock input.
PAGE 7
Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking MSB TRACKING OUT[3:1] ONLY LSB SOURCE OR SINK MODE 127 POSITIONS EACH FOR SOURCE AND SINK MODE CURRENT DAC[3:0] FS[3:0] Power-Supply Tracking Circuit OUT[3:0] By making use of the power-supply tracking circuitry, the DS4426 has the ability to source current on powerup. This current is additive with the current DAC source/sink currents and is determined by the value of the gain resistor, RG, and the supply voltage, VCC.
PAGE 8
DS4426 Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking V VMASTER VSLAVE DS4426 TRACKING DISABLED VTHRESHOLD GAIN ERROR TRACKING RANGE: DS4426 OVERRIDES SLAVE'S FEEDBACK LOOP t Figure 4. Enabling Power-Supply Tracking Using the THR Input THR Inputs for Enabling Power-Supply Tracking Comparators are used to individually enable/disable power-supply tracking based on the voltage presented to the corresponding THR pin relative to a fixed internal reference (VREF/2 = +0.
PAGE 9
Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking DS4426 5.0V VCC VCC VOUT 0.1μF 10kΩ 10kΩ 10kΩ MASTER DC-DC CONVERTER SDA SCL A0 A1 I 2C I2C CONTROL INTERFACE RF0 FB FS0 VREF REF 1.24V RE0 RFS0 OUT0 x3 FS[3:1] RFS[3:1] INP[3:1] 5.0V OUT[3:1] INN[3:1] RB[3:1] RG[3:1] VOUT GAIN[3:1] RA[3:1] VREF/2 10kΩ DS4426 SLAVE DC-DC CONVERTER COMP THR[3:1] RF[3:1] FB RE[3:1] RTHR[3:1] RD[3:1] RC[3:1] Figure 5.
PAGE 10
DS4426 Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking Table 1. Slave Addresses Table 2. Memory Addresses A1 A0 SLAVE ADDRESS (HEX) MEMORY ADDRESS (HEX) CURRENT SOURCE GND GND 90h F8h OUT0 GND VCC 92h F9h OUT1 VCC GND 94h FAh OUT2 VCC VCC 96h FBh OUT3 Inputs for Tracking in DC-DC Power Applications When enabling/disabling the power-supply tracking, a resistor-divider connected to the THR input sets the disable threshold (see VTHRESHOLD in Figure 4).
PAGE 11
Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking I2C Definitions The following terminology is commonly used to describe I2C data transfers: I 2 C Slave Address: The slave address of the DS4426 is determined by the state of the A0 and A1 pins (see Table 1). Master Device: The master device controls the slave devices on the bus. The master device generates SCL clock pulses and START and STOP conditions. Slave Devices: Slave devices send and receive data at the master’s request.
PAGE 12
DS4426 Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking SDA tBUF tF tSP tHD:STA tLOW SCL tHIGH tHD:STA tSU:STA tR tHD:DAT STOP tSU:STO tSU:DAT START REPEATED START NOTE: TIMING IS REFERENCED TO VIL(MAX) AND VIH(MIN). Figure 6.
PAGE 13
Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking Example Calculations for an Adjustable Power Supply In this example, the circuit shown in Figure 8 is used to margin a +2.0V supply by ±20%. The margined power supply has a DC-DC converter output voltage, VOUT, of +2.0V and a DC-DC converter feedback voltage, VFB, of +0.8V. To determine the relationship of R0A and R0B, start with the equation: IOUT0 is chosen to be 100µA (midrange source/sink current for the DS4426).
PAGE 14
Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking DS4426 Functional Diagram VCC calculated to be 4.00kΩ. The current DAC in this configuration allows the output voltage to be moved linearly from +1.6V to +2.4V using 127 settings. This corresponds to a resolution of 6.3mV/step. VCC Decoupling VCC SDA SCL A0 A1 I2C CONTROL INTERFACE FS0 VREF REF 1.24V OUT0 To achieve the best results when using the DS4426, decouple the power supply with a 0.01µF (or 0.1µF) capacitor.
PAGE 15
Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking PAGES CHANGED REVISION NUMBER REVISION DATE 0 4/08 Initial release. — 1 7/09 Added OUT[3:0] to the Absolute Maximum Ratings for the following condition: Voltage Range on A0, A1, FS[3:0], GAIN[3:1], INN[3:1], INP[3:1], and THR[3:1]. 2 DESCRIPTION Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.