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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 2C-Compatible Serial Interface ♦ Two Address Input Pins Allow Up to Four Devices on Same I2C 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 SCL OUT0 OUT1 OUT2 OUT3 SDA THR1 DNC THR3 FS0 INN3 INP3 GAIN3 4567 2021 19 17 16 15 GAIN2 GAIN1 INN1 INP1 VCC THR2 28 8N.C. GND FS3 23 13 INP2FS2 22 14 INN2FS1 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.

Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking 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 specificatio ns is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Voltage Range on V Voltage Range on A0, A1, FS[3:0], GAIN[3:1], INN[3:1], INP[3:1], THR[3:1], and OUT[3:0] CC + 0.5V)* J-STD-020 Specification. PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Supply Voltage V CC (Note 1) 2.7 5.5 V Input Logic 1 (SDA, SCL, A0, A1) VIH 0.7 x VCC VCC + 0.3 V Input Logic 0 (SDA, SCL, A0, A1) VIL -0.3 0.3 x VCC V Full-Scale Resistor Values R FS[3:0] (Note 2) 40 160 k DC ELECTRICAL CHARACTERISTICS (VCC = +2.7V to +5.5V, TA = -40°C to +85°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Supply Current I CC V CC = +5.5V (Note 3) 0.9 mA Input Leakage Current (SDA, SCL) IIL V CC = +5.5V -1 +1 μA RFS Voltage V RFS T A = +25°C 0.940 0.990 1.040 V Reference Voltage V REF 1.24 V Temperature Coefficient ±100 ppm/°C Output Leakage Current (SDA) I L -1 +1 μA VOL = +0.4V 3 Output-Current Low (SDA) I OL VOL = +0.6V 6 mA I/O Capacitance C I/O 10 pF DAC OUTPUT CURRENT CHARACTERISTICS (VCC = +2.7V to +5.5V, TA = -40°C to +85°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DC source, VOUT measured at +1.2V 0.33 Output Current Variation Due to Power-Supply Change DC sink, V OUT measured at +1.2V 0.33 %/V DC source, VCC = +3.6V 0.15 Output Current Variation Due to Output-Voltage Change DC sink, V CC = +3.6V 0.30 %/V *Not to exceed +6.0V.

Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking DAC OUTPUT CURRENT CHARACTERISTICS (continued) (VCC = +2.7V to +5.5V, TA = -40°C to +85°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Output Voltage for Sinking Current VOUT:SINK (Note 4) 0.5 3.5 V Output Voltage for Sourcing Current VOUT:SOURCE (Note 4) 0 VCC - 0.75 V Full-Scale Sink Output Current I OUT:SINK (Note 4) 50 200 μA Full-Scale Source Output Current I OUT:SOURCE (Note 4) -200 -50 μA Output-Current Full-Scale Accuracy IOUT:FS T A = +25°C ±5 % Output-Current Temperature Coefficient IOUT:TC (Note 5) ±130 ppm/ °C Output-Current Power-Supply Rejection Ratio 0.33 %/V Output-Leakage Current at Zero Current Setting IZERO -1 +1 μA Output-Current Differential Linearity DNL (Note 6) 0.5 LSB Output-Current Integral Linearity INL (Note 7) 1 LSB I2C ELECTRICAL CHARACTERISTICS PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS SCL Clock Frequency f SCL (Note 8) 0 400 kHz Bus Free Time Between STOP and START Conditions tBUF 1.3 μs Hold Time (Repeated) START Condition tHD:STA 0.6 μs Low Period of SCL t LOW 1.3 μs High Period of SCL t HIGH 0.6 μs Data Hold Time t HD:DAT 0 0.9 μs Data Setup Time t SU:DAT 100 ns START Setup Time t SU:STA 0.6 μs SDA and SCL Rise Time t R (Note 9) 20 + 0.1CB 300 ns SDA and SCL Fall Time t F (Note 9) 20 + 0.1CB 300 ns STOP Setup Time t SU:STO 0.6 μs SDA and SCL Capacitive Loading CB (Note 9) 400 pF

Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking 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 (RFS[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 VCC or GND. SDA and SCL are connected to VCC. Excludes current through RFS resistors (IRFS). Total current including IRFS is ICC + (2 x IRFS). 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 I2C standard-mode timing. Note 9: CB—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 SYMBOL CONDITIONS MIN TYP MAX UNITS Input Divider Ratio R DIV RA/RB and RC/RD 0.5 1 Output Load R L RL = (RF x RE )/(RF+RE) 1 20 k Feedback Resistor Ratio R F/RB 0.5 4.5 Gain Resistor R G 0.8 10 k Gain Setting Ratio R L/RG 1.4 5 RL/RG = 2, RL = 5k, VCC = +3.6V, TA = +25°C 2.4 Power-Supply Tracking Gain G VI RL/RG = 5, RL = 5k, VCC = +3.6V, TA = +25°C 3.8 6.2 10 mA/V Power-Supply Tracking Input Bias Current IB 1 μA Power-Supply Tracking Input Voltage VIN INP[3:1] and INN[3:1] 0 VCC - 1.4 V Unity Gain Bandwidth GBW R L/RG = 1.4; RL = 5k 12 MHz Output Voltage While Tracking V OUT:TRK Switch closed, V CC = +3.0V, measured at OUT[3:1], RL = 5k 0 1.5 V Output Current While Tracking I OUT:TRK RL/RG = 1.4, R G = 1k, VCC = +3.0V, VFB = +0.8V 1 mA Tracking Accuracy ±600 mV Output Leakage I BC Switch open 0.5 μA Comparator Input Bias Current I OFF 1 μA Comparator Input Offset V OS ±5 mV Switch Delay t DC 5 μs Comparator Hysteresis V HYS 12.5 mV

Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking SUPPLY CURRENT vs. SUPPLY VOLTAGE DS4426 toc01 SUPPLY VOLTAGE (V) SUPPLY CURRENT (μA) 425 450 475 500 525 550 575 600 400 2.5 5.5 SDA = SCL = THR[3:1] = VCC GAIN[3:1] = FS[3:0] = OUT[3:0] = OPEN INP[3:1] = INN[3:1] = GND SUPPLY CURRENT vs. TEMPERATURE DS4426 toc02 TEMPERATURE (°C) SUPPLY CURRENT (μA) 8060-20 0 20 40 425 450 475 500 525 550 575 600 400 -40 SDA = SCL = THR[3:1] = VCC GAIN[3:1] = FS[3:0] = OUT[3:0] = OPEN INP[3:1] = INN[3:1] = GND VCC = +5.5V VCC = +3.3V VCC = +2.7V VOLTCO (SOURCE) DS4426 toc03 VOUT (V) IOUT (μA) 4321 -225 -200 -175 -150 -250 SDA = SCL = THR[3:1] = VCC GAIN[3:1] = OPEN INP[3:1] = INN[3:1] = GND 40kΩ LOAD ON FS[3:0]. VCC = +5.5V VOLTCO (SINK) DS4426 toc04 VOUT (V) IOUT (μA) 175 200 225 250 150 0 4.0 SDA = SCL = THR[3:1] = VCC GAIN[3:1] = OPEN INP[3:1] = INN[3:1] = GND 40kΩ LOAD ON FS[3:0]. VCC = +5.5V TEMPERATURE COEFFICIENT vs. SETTING (SOURCE) DS4426 toc05 SETTING (DEC) TEMPERATURE COEFFICIENT (°C/ppm) 125100755025 100 150 200 250 300 -50 RANGE FOR THE 50μA TO 200μA CURRENT SOURCE RANGE +25°C TO -40°C +25°C TO +85°C TEMPERATURE COEFFICIENT vs. SETTING (SINK) DS4426 toc06 SETTING (DEC) TEMPERATURE COEFFICIENT (°C/ppm) 125100755025 -150 -50 150 250 350 450 550 650 -250 RANGE FOR THE 50μA TO 200μA CURRENT SINK RANGE +25°C TO -40°C +25°C TO +85°C INTEGRAL LINEARITY DS4426 toc07 SETTING (DEC) INL (LSB) 125100755025 -0.8 -0.6 -0.4 -0.2 0.2 0.4 0.6 0.8 1.0 -1.0 RANGE FOR THE 50μA TO 200μA CURRENT SOURCE AND SINK RANGE DIFFERENTIAL LINEARITY DS4426 toc08 SETTING (DEC) DNL (LSB) 125100755025 -0.8 -0.6 -0.4 -0.2 0.2 0.4 0.6 0.8 1.0 -1.0 RANGE FOR THE 50μA TO 200μA CURRENT SOURCE AND SINK RANGE Typical Operating Characteristics (TA = +25°C, unless otherwise noted.)

The DS4426 contains four I 2C-adjustable current sources that are each capable of sinking and sourcing current. Three of the current outputs (OUT[3:1]) also have power-supply tracking circuitry that allows addi- tional current to be sourced during power-up. Adjustable Current DACs Each output (OUT[3:0]) has 127 sink and 127 source settings that are programmed through the I 2C interface. The full-scale current ranges (and corresponding step sizes) of the outputs are determined by external resis- tors connected to the corresponding FS pins (see Figure 1). The formula to determine the external resistor values (R FS) for each output is given by: where IFS is the desired full-scale current value, VRFS is the R FS voltage (see the DC Electrical Characteristics table), and RFS is the external resistor value. To calculate the output-current value (IOUT) based on the corresponding DAC value (see Table 2 for correspond- ing memory addresses), use the following equation: On power-up, the DS4426 current DAC outputs are set to zero current. This is done to prevent the device from sinking or sourcing an incorrect current before the sys- tem host controller has a chance to modify its setting. Note, however, that if power-supply tracking is enabled (see the Power-Supply Tracking Circuit section), then the DS4426 can still source current at power-up. When used in adjustable power-supply applications (see Figure 8), the DS4426 does not affect the initial power-up voltage of the supply because it defaults to providing zero output current on power-up unless power-supply tracking is enabled. As it sources or sinks current into the feedback voltage node, it changes the amount of output voltage required by the regulator to reach its steady-state operating point. I DACValue dec IOUT FS=× () 127 R V IFS RFS FS = × ×16 127 DS4426 Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking Pin Description PIN NAME FUNCTION 1 SDA Serial Data Input/Output. I 2C data pin. 2 SCL Serial Clock Input. I 2C clock input.

3 V CC Voltage Supply

4 OUT0 Current DAC Output

5, 6, 7 OUT1, OUT2, OUT3 Current DAC and Tracking Control Output

8 GND Ground

9 A0 I 2C Address Input 0

10 A1 I 2C Address Input 1

11, 13, 15 INP1, INP2, INP3 Power-Supply Tracking Positive Input 12, 14, 16 INN1, INN2, INN3 Power-Supply Tracking Negative Input 17, 19, 20 THR3, THR2, THR1 Threshold Input. Comparator input used to set threshold for tracking enable/disable based on V REF/2.

18 DNC Do Not Connect

21–24 FS0, FS1, FS2, FS3 Full-Scale Calibration Input. A resistor-to-ground on this input determines full- scale output current on the associated output. 25, 26, 27 GAIN3, GAIN2, GAIN1 Gain Adjustment Pin. Connect a resistor between this pin and V CC. 28 N.C. No Connection — EP Exposed Pad. No connection.

out of its 7-bit sink or source resolution. sented to the corresponding threshold (THR) pins. Power-Supply Tracking Characteristics table). age difference seen at the INP and INN inputs.

127 POSITIONS

Figure 1. Current DAC Detail Figure 2. Gain Stage Figure 3. INP and INN Differential Inputs

three slave DC-DCs. See Figure 5 for more information. Figure 4. Enabling Power-Supply Tracking Using the THR Input

Nonratiometric tracking is the special case where KSM = 1. tracking. See Figure 4 for more information. Figure 5. Typical DC-DC Power-Supply Tracking Application

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 dis- able threshold (see V THRESHOLD in Figure 4). The top of the resistor-divider must be connected to the master DC-DC voltage for correct operation. Below this thresh- old, the tracking circuit is active. Power-Supply Sequencing The DS4426 can be used to perform power-supply sequencing. This is a subset of power-supply tracking with modifications to the external resistor network. The basic concept is that the DS4426 sources maximum current into the slave power supply's feedback node until a voltage in the system has risen above a specific voltage level. By sourcing the maximum current into the feedback node, the power supply's output is held off. Maximum sourcing current is achieved with two steps: 1) Apply the maximum allowed input voltage across INP and INN. Connect INP to V CC - 1.4V using a voltage-divider to ground. Connect INN to ground. 2) Set the gain to the maximum allowed (R L/RG = 5). The slave power supply is allowed to turn on once the voltage on THR is greater than V REF/2. Use a resistor- divider connected to the rising system voltage to scale the trip point to V REF/2. I2C Slave Address The DS4426 responds to one of four I2C slave address- es determined by the state of the input on the two address inputs. The two input states are connected to V CC or connected to ground. Memory Organization The DS4426’s current sources are controlled by writing to memory addresses listed in Table 2. The format of each of the output control registers is given by: where: For example: R FS0 = 80kΩ and register 0xF8h is written to a value of 0xAAh. Use the following formula to calculate the out- put current: I The MSB of the output register is 1, so the output is sourcing the value corresponding to position 2Ah (42 decimal). The magnitude of the output current is equal to the following: 99.22µA x (42/127) = 32.8125µA DS4426 Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking A1 A0 SLAVE ADDRESS (HEX) GND GND 90h GND V CC 92h VCC GND 94h VCC V CC 96h Table 1. Slave Addresses Table 2. Memory Addresses sinks current. For sink, S = 0. of the state of the sign bit.

*VOUT AND VFB VALUES ARE DETERMINED BY THE DC-DC CONVERTER AND SHOULD NOT BE CONFUSED WITH VOUT AND VREF OF THE DS4426. Figure 8. Example Typical Application Circuit

Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking calculated to be 4.00k Ω. The current DAC in this con- figuration allows the output voltage to be moved linearly from +1.6V to +2.4V using 127 settings. This corre- sponds to a resolution of 6.3mV/step. VCC Decoupling To achieve the best results when using the DS4426, decouple the power supply with a 0.01µF (or 0.1µF) capacitor. Use a high-quality, ceramic, surface-mount capacitor if possible. Surface-mount components mini- mize lead inductance, which improves performance. Ceramic capacitors tend to have adequate high-fre- quency response for decoupling applications. DS4426 SDA VCC SCL FS0 OUT0 I2C CONTROL INTERFACE VCC VREF REF 1.24V INP1 FS1 OUT1 INN1 THR1 GAIN1 VREF/2 INP2 FS2 OUT2 INN2 THR2 GAIN2 VREF/2 INP3 FS3 OUT3 INN3 THR3 GND GAIN3 VREF/2 Functional Diagram

Package Information

For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAGE CODE DOCUMENT NO.

28 TQFN T2844+1 21-0139

Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circu it patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15 © 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.

Revision History

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