19-3379; Rev 4; 1/06 ৰۇ భᄋຶ 双路、256抽头、非易失、 I2C接口、数字电位器 ___________________________________特性 MAX5477/MAX5478/MAX5479 非易失、双路、线性变化 的数字电位器能实现机械电位器的功能，采用简单的 2 线 数字接口取代机械调节。每个器件都具有与分立电位器 或可变电阻相同的功能，提供 256 级抽头。 ♦ 上电后从非易失存储器调用滑动端位置 这些器件内置非易失 EEPROM ，用来存储滑动端的位 置，以便在上电时进行初始化。器件的写保护功能可以 防止对 EEPROM 意外重写。与快速模式 I2C 兼容的串行接 口允许 400kbps 的通信速率，在多数应用中减小了 电路板尺寸，并简化了布线。三个地址输入提供 8 个唯一 地址。 MAX5477/MAX5478/MAX5479 提供三种标称电阻值： 10kΩ (MAX5477)、50kΩ (MAX5478)及 100kΩ (MAX5479)。 标称端对端电阻温度系数为 70ppm/˚C，比例系数为 10ppm/˚C 。低温度系数使这些器件尤其适合于需要低温 度漂移可变电阻的应用，如低失调、可编程增益放大器 电路。 MAX5477/MAX5478/MAX5479 采用 16 引脚、 3mm x 3mm x 0.8mm、薄型 QFN 以及 14 引脚、4.4mm x 5mm、 TSSOP 封装，工作在 -40˚C 至 +85˚C 的扩展级温度范 围内。 ♦ EEPROM写保护 ♦ 微型3mm x 3mm x 0.8mm、薄型QFN封装 ♦ 端对端电阻温度系数：70ppm/˚C ♦ 比例温度系数：10ppm/˚C ♦ 400kbps、快速I2C* 兼容串行接口 ♦ 1µA (最大值)静态供电电流 ♦ 单电源+2.7V到+5.25V供电 ♦ 每个电位器256级抽头 ♦ 分压模式下DNL：±0.5 LSB ♦ 分压模式下INL：±1 LSB _______________________________功能框图 VDD GND HA 8-BIT SHIFT REGISTER 8 2 SCL 替代机械电位器 WA IC INTERFACE LA 16-BIT NV MEMORY HB 8 WP 256 POSITION DECODER 256 WB MAX5477 MAX5478 MAX5479 A0 低失调可编程增益放大器 256 POR SDA ________________________________应用 8 16-BIT LATCH 256 POSITION DECODER A1 A2 LB 音量控制 * 购买 Maxim Integrated Products, Inc.或其从属授权公司的 I 2C 产 品，即得到了 Philips I 2 C 的专利许可、将这些产品用于符合 Philips 定义的 I 2C 标准规范的系统。 液晶显示器(LCD)对比度控制 ___________________________________________________________ 定购信息/ 选型指南 PART MAX5477ETE* TEMP RANGE -40°C to +85°C PIN-PACKAGE 16 Thin QFN END-TO-END RESISTANCE (kΩ) 10 TOP MARK ABO PACKAGE CODE T1633F-3 MAX5477EUD -40°C to +85°C 14 TSSOP 10 — U14-1 MAX5478ETE* -40°C to +85°C 16 Thin QFN 50 ABP T1633F-3 MAX5478EUD -40°C to +85°C 14 TSSOP 50 — U14-1 MAX5479ETE* -40°C to +85°C 16 Thin QFN 100 ABQ T1633F-3 MAX5479EUD -40°C to +85°C 14 TSSOP 100 — U14-1 *未来产品—请与工厂联系。 引脚配置在数据资料的最后给出。 ________________________________________________________________ Maxim Integrated Products 1 本文是Maxim正式英文资料的译文，Maxim不对翻译中存在的差异或由此产生的错误负责。请注意译文中可能存在文字组织或 翻译错误，如需确认任何词语的准确性，请参考 Maxim提供的英文版资料。 索取免费样品和最新版的数据资料，请访问Maxim的主页：www.maxim-ic.com.cn。 MAX5477/MAX5478/MAX5479 ___________________________________概述 MAX5477/MAX5478/MAX5479 双路、256抽头、非易失、 I2C接口、数字电位器 ABSOLUTE MAXIMUM RATINGS SDA, SCL, VDD to GND .........................................-0.3V to +6.0V All Other Pins to GND.................................-0.3V to (VDD + 0.3V) Maximum Continuous Current into H_, L_, and W_ MAX5477......................................................................±5.0mA MAX5478......................................................................±1.3mA MAX5479......................................................................±0.6mA Continuous Power Dissipation (TA = +70°C) 16-Pin Thin QFN (derate 17.5mW/°C above +70°C) 1399mW 14-Pin TSSOP (derate 9.1mW/°C above +70°C) .........727mW Operating Temperature Range ...........................-40°C to +85°C Maximum Junction Temperature .....................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°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. ELECTRICAL CHARACTERISTICS (VDD = +2.7V to +5.25V, H_ = VDD, L_ = GND, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = +5V, TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DC PERFORMANCE (VOLTAGE-DIVIDER MODE) Resolution 256 Taps Integral Nonlinearity INL (Note 2) ±1 LSB Differential Nonlinearity DNL (Note 2) ±0.5 LSB ±1 LSB Dual Code Matching End-to-End Resistance Temperature Coefficient R0 and R1 set to same code (all codes) TCR Ratiometric Resistance Temperature Coefficient Full-Scale Error Zero-Scale Error 70 ppm/°C 10 ppm/°C MAX5477 -4 MAX5478 -0.6 MAX5479 -0.3 MAX5477 4 MAX5478 0.6 MAX5479 0.3 LSB LSB DC PERFORMANCE (VARIABLE-RESISTOR MODE) Integral Nonlinearity (Note 3) INL Differential Nonlinearity (Note 3) DNL VDD = 3V ±3 VDD = 5V ±1.5 MAX5477 Dual Code Matching LSB ±1 MAX5478 ±1 MAX5479 ±1 R0 and R1 set to same code (all codes), VDD = 3V or 5V ±3 LSB LSB DC PERFORMANCE (RESISTOR CHARACTERISTICS) 2 Wiper Resistance RW Wiper Capacitance CW End-to-End Resistance RHL (Note 4) 325 675 10 MAX5477 7.5 10 12.5 MAX5478 37.5 50 62.5 MAX5479 75 100 125 _______________________________________________________________________________________ Ω pF kΩ 双路、256抽头、非易失、 I2C接口、数字电位器 (VDD = +2.7V to +5.25V, H_ = VDD, L_ = GND, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = +5V, TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DIGITAL INPUTS Input High Voltage (Note 5) VIH VDD = 3.4V to 5.25V VDD < 3.4V 2.4 V 0.7 x VDD Input Low Voltage VIL (Note 5) 0.8 V Output Low Voltage VOL ISINK = 3mA 0.4 V WP Pullup Resistance IWP Input Leakage Current ILEAK 255 kΩ ±1 Input Capacitance µA 5 pF HA = 1kHz (0 to VDD), LA = GND, LB = GND, measure WB -75 dB MAX5477 400 MAX5478 100 MAX5479 50 DYNAMIC CHARACTERISTICS Crosstalk 3dB Bandwidth (Note 6) Total Harmonic Distortion Plus Noise THD+N H_ = 1VRMS, f = 1kHz, L_ = GND, measure W_ kHz 0.003 % TA = +85°C 50 Years TA = +25°C 200,000 TA = +85°C 50,000 NONVOLATILE MEMORY RELIABILITY Data Retention Endurance Stores POWER SUPPLY Power-Supply Voltage VDD 2.70 Writing to EEPROM, digital inputs at GND or VDD, TA = +25°C (Note 7) Supply Current IDD Normal operation, digital WP = GND inputs at GND or VDD, WP = VDD TA = +25°C 5.25 250 400 15 20.6 0.5 1 V µA TIMING CHARACTERISTICS (VDD = +2.7V to +5.25V, H_ = VDD, L_ = GND, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = +5V, TA = +25°C. See Figure 1.) (Notes 8 and 9) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS ANALOG SECTION Wiper Settling Time (Note 10) tWS MAX5477 325 MAX5478 500 MAX5479 1000 ns DIGITAL SECTION SCL Clock Frequency fSCL 400 kHz Setup Time for START Condition tSU:STA 0.6 µs Hold Time for START Condition tHD:STA 0.6 µs _______________________________________________________________________________________ 3 MAX5477/MAX5478/MAX5479 ELECTRICAL CHARACTERISTICS (continued) MAX5477/MAX5478/MAX5479 双路、256抽头、非易失、 I2C接口、数字电位器 TIMING CHARACTERISTICS (continued) (VDD = +2.7V to +5.25V, H_ = VDD, L_ = GND, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = +5V, TA = +25°C. See Figure 1.) (Notes 8 and 9) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS SCL High Time tHIGH 0.6 µs SCL Low Time tLOW 1.3 µs Data Setup Time tSU:DAT 100 Data Hold Time tHD:DAT 0 SDA, SCL Rise Time SDA, SCL Fall Time tR tF Setup Time for STOP Condition tSU:STO Bus Free Time Between STOP and START Condition tBUF Pulse Width of Spike Suppressed tSP Capacitive Load for Each Bus Line CB ns 0.9 µs 300 ns 300 Minimum power-up rate = 0.2V/µs ns 0.6 µs 1.3 µs (Note 11) 50 ns 400 pF Note 1: All devices are production tested at TA = +25°C and are guaranteed by design and characterization for -40°C < TA < +85°C. Note 2: The DNL and INL are measured with the potentiometer configured as a voltage-divider with H_ = VDD and L_ = GND. The wiper terminal is unloaded and measured with a high-input-impedance voltmeter. Note 3: The DNL and INL are measured with the potentiometer configured as a variable resistor. H_ is unconnected and L_ = GND. For VDD = +5V, the wiper is driven with 400µA (MAX5477), 80µA (MAX5478), or 40µA (MAX5479). For VDD = +3V, the wiper is driven with 200µA (MAX5477), 40µA (MAX5478), or 20µA (MAX5479). Note 4: The wiper resistance is measured using the source currents given in Note 3. Note 5: The devices draw current in excess of the specified supply current when the digital inputs are driven with voltages between (VDD - 0.5V) and (GND + 0.5V). See Supply Current vs. Digital Input Voltage in the Typical Operating Characteristics. Note 6: Wiper at midscale with a 10pF load (DC measurement). L_ = GND, an AC source is applied to H_, and the W_ output is measured. A 3dB bandwidth occurs when the AC W_/H_ value is 3dB lower than the DC W_/H_ value. Note 7: The programming current exists only during power-up and EEPROM writes. Note 8: The SCL clock period includes rise and fall times (tR = tF). All digital input signals are specified with tR = tF = 2ns and timed from a voltage level of (VIL + VIH) / 2. Note 9: Digital timing is guaranteed by design and characterization, and is not production tested. Note 10: This is measured from the STOP pulse to the time it takes the output to reach 50% of the output step size (divider mode). It is measured with a maximum external capacitive load of 10pF. Note 11: An appropriate bus pullup resistance must be selected depending on board capacitance. Refer to the I2C-bus specification document linked to this web address: www.semiconductors.philips.com/acrobat/literature/9398/39340011.pdf Note 12: The idle time begins from the initiation of the STOP pulse. 4 _______________________________________________________________________________________ 双路、256抽头、非易失、 I2C接口、数字电位器 SUPPLY CURRENT vs. TEMPERATURE (MAX5477) 0.6 VCC = 5V 0.4 VCC = 3V VCC = 5V 13 11 9 0.2 7 0 5 VCC = 3V 500 MAX5477/78/79 toc02 WP = GND 450 400 WIPER RESISTANCE (Ω) 0.8 15 MAX5477/78/79 toc1a WP = VDD SUPPLY CURRENT (μA) MAX5477/78/79 toc01 1.0 SUPPLY CURRENT (μA) WIPER RESISTANCE vs. INPUT CODE SUPPLY CURRENT vs. TEMPERATURE 350 300 250 200 150 100 50 -40 -15 10 35 60 85 TEMPERATURE (°C) 0 -40 -15 10 35 60 0 85 TAP-TO-TAP SWITCHING TRANSIENT TAP-TO-TAP SWITCHING TRANSIENT 32 64 96 128 160 192 224 256 INPUT CODE TEMPERATURE (°C) TAP-TO-TAP SWITCHING TRANSIENT MAX5477/78/79 toc04 MAX5477/78/79 toc03 MAX5477 CL = 10pF H_ = VDD FROM TAP 00 TO TAP 04 W_ 20mV/div MAX5478 CL = 10pF H_ = VDD FROM TAP 00 TO TAP 04 MAX5479 CW_ = 10pF H_ = VDD FROM TAP 00 TO TAP 04 1μs/div 200ns/div WIPER TRANSIENT AT POWER-ON MAX5477/78/79 toc07 MAX5477/78/79 toc06 W_ 20mV/div 400ns/div WIPER TRANSIENT AT POWER-ON WIPER TRANSIENT AT POWER-ON SDA 2V/div SDA 2V/div SDA 2V/div W_ 50mV/div MAX5477/78/79 toc05 VDD 2V/div MAX5477/78/79 toc08 VDD 2V/div VDD 2V/div W_ 1V/div W_ 1V/div MAX5477 TAP = 128 2μs/div MAX5479 TAP = 128 MAX5478 TAP = 128 4μs/div W_ 1V/div 2μs/div _______________________________________________________________________________________ 5 MAX5477/MAX5478/MAX5479 _____________________________________________________________________典型工作特性 (VDD = +5V, H_ = VDD, L_ = GND, TA = +25°C, unless otherwise noted.) ______________________________________________________________典型工作特性( 续 ) (VDD = +5V, H_ = VDD, L_ = GND, TA = +25°C, unless otherwise noted.) 0.2 MAX5478 0.2 0.15 0.05 0 0.1 INL (LSB) 0.20 0.10 0 32 64 96 -0.1 -0.2 -0.2 128 160 192 224 256 -0.3 0 32 64 96 CODE DIFFERENTIAL NONLINEARITY vs. CODE (VDM MODE) 0.2 0 0.10 -0.2 -0.2 -0.3 -0.3 MAX5478 0.08 0.06 0.04 DNL (LSB) INL (LSB) 0 -0.1 128 160 192 224 256 DIFFERENTIAL NONLINEARITY vs. CODE (VRM MODE) 0.2 -0.1 96 INTEGRAL NONLINEARITY vs. CODE (VRM MODE) 0.1 0 64 CODE MAX5478 0.1 32 CODE MAX5477/78/79 toc13 MAX5478 128 160 192 224 256 0.3 MAX5477/78/79 toc12 0.3 0 -0.1 -0.3 0 DNL (LSB) 0.3 0.1 DNL (LSB) INL (LSB) 0.25 MAX5477 MAX5477/78/79 toc14 0.30 0.3 INTEGRAL NONLINEARITY vs. CODE (VDM MODE) MAX5477/78/79 toc10 MAX5477 MAX5477/78/79 toc09 0.35 DIFFERENTIAL NONLINEARITY vs. CODE (VDM MODE) MAX5477/78/79 toc11 INTEGRAL NONLINEARITY vs. CODE (VDM MODE) 0.02 0 -0.02 -0.04 -0.06 -0.08 64 96 64 96 128 160 192 224 256 64 96 128 160 192 224 256 DIFFERENTIAL NONLINEARITY vs. CODE (VDM MODE) INTEGRAL NONLINEARITY vs. CODE (VRM MODE) MAX5477/78/79 toc15 0.08 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0 -0.02 -0.04 -0.06 -0.08 -0.10 -0.12 -0.14 MAX5479 0 -0.04 -0.08 -0.12 -0.16 -0.20 64 96 128 160 192 224 256 CODE 0.20 MAX5479 0.16 0.12 0.08 INL (LSB) DNL (LSB) 0.04 32 32 INTEGRAL NONLINEARITY vs. CODE (VDM MODE) MAX5479 0 0 CODE 0.12 6 32 CODE 0.20 0.16 0 128 160 192 224 256 CODE MAX5477/78/79 toc17 32 -0.10 MAX5477/78/79 toc16 0 INL (LSB) MAX5477/MAX5478/MAX5479 双路、256抽头、非易失、 I2C接口、数字电位器 0.04 0 -0.04 -0.08 -0.12 -0.16 -0.20 0 32 64 96 128 160 192 224 256 0 32 64 96 CODE _______________________________________________________________________________________ 128 160 192 224 256 CODE 双路、256抽头、非易失、 I2C接口、数字电位器 CROSSTALK vs. FREQUENCY (MAX5477) -30 0 -0.04 -20 -40 -50 -60 -30 -40 -50 -60 -0.08 -70 -70 -0.12 -80 -80 -0.16 -90 -90 -0.20 -100 -100 32 64 96 128 160 192 224 256 0.1 1 10 100 1000 FREQUENCY (kHz) CODE CROSSTALK vs. FREQUENCY (MAX5479) -30 CW_ = 10pF 0 -1 -60 CW_ = 50pF -3 -1 -4 -2 -3 -4 -6 -7 -7 -100 -8 -8 10 100 1000 10,000 0.1 1 FREQUENCY (kHz) MIDSCALE WIPER RESPONSE vs. FREQUENCY (MAX5479) 1 0.1 1 10 100 1000 FREQUENCY (kHz) 1 MIDSCALE TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY (MAX5478) 10 MIDSCALE 1 THD+N (%) 0.1 THD+N (%) GAIN (dB) 0 1000 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY (MAX5477) MAX5477/78/79 toc24 2 10 100 FREQUENCY (kHz) MAX5477/78/79 toc25 1 CW_ = 50pF -5 -90 0.1 1000 CW_ = 10pF 0 -6 -80 100 1 -5 -70 10 2 GAIN (dB) GAIN (dB) -50 1 MIDSCALE WIPER RESPONSE vs. FREQUENCY (MAX5478) -2 -40 0.1 FREQUENCY (kHz) 1 MAX5477/78/79 toc21 CW_ = 10pF -20 CROSSTALK (dB) 0.01 MIDSCALE WIPER RESPONSE vs. FREQUENCY (MAX5477) 0 -10 10,000 MAX5477/78/79 toc22 0 MAX5477/78/79 toc26 0.04 MAX5477/78/79 toc20 -20 CROSSTALK (dB) DNL (LSB) 0.08 CW_ = 10pF -10 CROSSTALK (dB) 0.12 CW_ = 10pF -10 0 MAX5477/78/79 toc19 MAX5479 0.16 0 MAX5477/78/79 toc18 0.20 CROSSTALK vs. FREQUENCY (MAX5478) MAX5477 toc23 DIFFERENTIAL NONLINEARITY vs. CODE (VRM MODE) -1 -2 CW_ = 10pF -3 0.1 0.01 0.01 0.001 -4 CW_ = 50pF 0.001 -5 0.1 1 10 FREQUENCY (kHz) 100 1000 0.0001 0.01 0.1 1 10 FREQUENCY (kHz) 100 0.01 0.1 1 10 100 FREQUENCY (kHz) _______________________________________________________________________________________ 7 MAX5477/MAX5478/MAX5479 ______________________________________________________________典型工作特性( 续 ) (VDD = +5V, H_ = VDD, L_ = GND, TA = +25°C, unless otherwise noted.) ______________________________________________________________典型工作特性( 续 ) (VDD = +5V, H_ = VDD, L_ = GND, TA = +25°C, unless otherwise noted.) TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY (MAX5479) 0.1 0.01 0.001 0.2 0 -0.2 -0.4 -0.6 0.0001 0.1 1 10 100 10 35 60 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 -40 85 -15 0.3 0.2 0.1 0 -0.1 -0.2 600 550 500 SUPPLY CURRENT (μA) 0.4 35 SUPPLY CURRENT vs. DIGITAL INPUT VOLTAGE MAX5477/78/79 toc30 0.5 10 TEMPERATURE (°C) TEMPERATURE (°C) END-TO-END RESISTANCE % CHANGE vs. TEMPERATURE (MAX5479) END-TO-END RESISTANCE CHANGE (%) 0.3 -0.5 -15 -40 FREQUENCY (kHz) WP = GND 450 400 350 300 250 200 -0.3 150 100 -0.4 50 VCC = 5V VCC = 3V 0 -0.5 -40 -15 10 35 TEMPERATURE (°C) 8 0.4 MAX5477/78/79 toc31 0.01 MAX5477/78/79 toc29 0.4 END-TO-END RESISTANCE CHANGE (%) 1 0.5 MAX5477/78/79 toc28 0.6 END-TO-END RESISTANCE CHANGE (%) MIDSCALE END-TO-END RESISTANCE % CHANGE vs. TEMPERATURE (MAX5478) END-TO-END RESISTANCE % CHANGE vs. TEMPERATURE (MAX5477) MAX5477/78/79 toc27 10 THD+N (%) MAX5477/MAX5478/MAX5479 双路、256抽头、非易失、 I2C接口、数字电位器 60 85 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 DIGITAL INPUT VOLTAGE (V) _______________________________________________________________________________________ 60 85 双路、256抽头、非易失、 I2C接口、数字电位器 引脚 名称 功能 TSSOP 薄型 QFN 1 15 HA A电位器高端。 2 14 WA A电位器滑动端。 3 13 LA A电位器低端。 4 12 HB B电位器高端。 5 11 WB B电位器滑动端。 6 10 LB B电位器低端。 7 9 WP 写保护输入。接 GND允许更改滑动端位置以及在 EEPROM中的存储数据。 接 VDD 或开路则使EEPROM处于写保护。操作说明请参考写保护(WP)部分。 8 7 GND 9 6 A2 地址输入2。接VDD 或GND (见表1)。 10 5 A1 地址输入1。接VDD 或GND (见表1)。 地址输入0。接VDD 或GND (见表1)。 地。 11 4 A0 12 3 SDA I2C串行数据。 13 2 SCL I2C时钟输入。 14 1 VDD 电源输入。连接+2.7V到+5.25V电源至VDD，并使用尽可能靠近器件的0.1µF电容旁路VDD 至 GND。 — 8, 16 N.C. 不连接。无内部连接。 — EP EP 裸露焊盘。接GND或悬空。 SDA tBUF tSU:DAT tSU:STA tHD:DAT tLOW tHD:STA tSU:STO SCL tHIGH tHD:STA tR tF START CONDITION (S) REPEATED START CONDITION (SR) ACKNOWLEDGE (A) STOP CONDITION (P) START CONDITION (S) PARAMETERS ARE MEASURED FROM 30% TO 70%. 图 1. I 2C 串行接口时序 _______________________________________________________________________________________ 9 MAX5477/MAX5478/MAX5479 ___________________________________________________________________引脚说明 MAX5477/MAX5478/MAX5479 双路、256抽头、非易失、 I2C接口、数字电位器 ____________________________ 详细说明 MAX5477/MAX5478/MAX5479 内置两个电阻阵列，每个 阵列包含 255 个电阻单元。 MAX5477 端到端总阻值为 10kΩ，MAX5478 端到端阻值为 50kΩ，MAX5479 端到端阻 值为 100kΩ。MAX5477/MAX5478/MAX5479 通过连接高 端、低端和滑动端可以构成标准分压器。只要保证各端电 压在 GND 和 VDD 之间，H_、L_ 和 W_ 端可以任意配置。 简单的 2 线 I 2C 兼容串行接口可以在 256 级抽头间调节滑 动端(图 2)。非易失存储器存储滑动端位置并在上电时恢 复滑动端的位置。非易失存储器能够保持数据50 年、滑动 端存储次数多达 200,000 次。 模拟电路 MAX5477/MAX5478/MAX5479 内置两个包含 255 个电阻 单元的电阻阵列；滑动端可连至 H_ 和 L_ 之间的 256 个抽 头点。滑动端位置的选择通过 I2C 接口对电位器编程实现。 每个电位器通过一个地址字节，一个命令字节和 8 位数据 设置滑动端位置。 MAX5477/MAX5478/MAX5479 的 H_ 和 L_ 端与机械电位器的两个终端相同。MAX5477/MAX5478/ MAX5479内置上电复位电路，在上电时从非易失存储器 自动装载滑动端位置。 表 1. 从地址 H_ ADDRESS INPUTS SLAVE ADDRESS A2 A1 A0 GND GND GND 0101000 GND GND VDD 0101001 GND VDD GND 0101010 GND VDD VDD 0101011 VDD GND GND 0101100 VDD GND VDD 0101101 VDD VDD GND 0101110 VDD VDD VDD 0101111 S256 R255 S255 R254 S254 RW 256-POSITION DECODER W_ S3 R2 WIPER CODE 02h S2 R1 S1 L_ 图 2. 电位器配置 10 ______________________________________________________________________________________ 双路、256抽头、非易失、 I2C接口、数字电位器 COMMAND WP = 0 WP = 1 I2C data is written to VREG. Wiper position updates with I2C data. No change to NVREG. Copy NVREG to VREG. Wiper position updates with NVREG data. No change to NVREG. Write to NVREG No change to VREG or wiper position. I2C data is written to NVREG. No change to VREG or wiper position. No change to NVREG. Copy NVREG to VREG Copy NVREG to VREG. Wiper position updates with NVREG data. No change to NVREG. Copy NVREG to VREG. Wiper position updates with NVREG data. No change to NVREG. Copy VREG to NVREG Copy VREG to NVREG. No change to VREG or wiper position. No change to VREG or wiper position. No change to NVREG. Write to VREG 表3. 命令字节 ADDRESS BYTE 1 SCL CYCLE NUMBER 2 3 4 5 6 7 COMMAND BYTE 8 START (S) A6 A5 A4 A3 A2 A1 A0 DATA BYTE 9 10 11 12 13 14 15 16 17 18 ACK (A) TX NV V R3 R2 R1 R0 19 20 21 22 23 24 25 26 ACK ACK D7 D6 D5 D4 D3 D2 D1 D0 (A) (A) VREG 0 1 0 1 A2 A1 A0 0 0 0 0 1 0 0 0 1 NVREG 0 1 0 1 A2 A1 A0 0 0 0 1 0 0 0 0 1 D7 D6 D5 D4 D3 D2 D1 D0 NVREGxVREG 0 1 0 1 A2 A1 A0 0 0 1 1 0 0 0 0 1 D7 D6 D5 D4 D3 D2 D1 D0 VREGxNVREG 0 1 0 1 A2 A1 A0 0 0 1 0 1 0 0 0 1 D7 D6 D5 D4 D3 D2 D1 D0 VREG 0 1 0 1 A2 A1 A0 0 0 0 0 1 0 0 1 0 D7 D6 D5 D4 D3 D2 D1 D0 NVREG 0 1 0 1 A2 A1 A0 0 0 0 1 0 0 0 1 0 D7 D6 D5 D4 D3 D2 D1 D0 NVREGxVREG 0 1 0 1 A2 A1 A0 0 0 1 1 0 0 0 1 0 D7 D6 D5 D4 D3 D2 D1 D0 VREGxNVREG 0 1 0 1 A2 A1 A0 0 0 1 0 1 0 0 1 0 D7 D6 D5 D4 D3 D2 D1 D0 VREG 0 1 0 1 A2 A1 A0 0 0 0 0 1 0 0 1 1 D7 D6 D5 D4 D3 D2 D1 D0 NVREG 0 1 0 1 A2 A1 A0 0 0 0 1 0 0 0 1 1 D7 D6 D5 D4 D3 D2 D1 D0 NVREGxVREG 0 1 0 1 A2 A1 A0 0 0 1 1 0 0 0 1 1 D7 D6 D5 D4 D3 D2 D1 D0 VREGxNVREG 0 1 0 1 A2 A1 A0 0 0 1 0 1 0 0 1 1 D7 D6 D5 D4 D3 D2 D1 D0 数字接口 MAX5477/MAX5478/MAX5479 内置非易失 EEPROM，用 于存储滑动端的位置，以便上电初始化。移位寄存器对 控制位和地址位进行解码，并将数据写入适当的数据寄 存器。数据可以写入易失存储器立即更新滑动端的位 置，也可以写入非易失寄存器进行存储(见表 3)。 易失寄存器在系统加电期间能够保持数据。一旦断电， 易失寄存器的内容被清除。非易失寄存器在系统断电时 仍能保存数据。一旦上电，上电复位电路将非易失寄存 器的内容传送到易失寄存器。 27 STOP NOTES (P) D7 D6 D5 D4 D3 D2 D1 D0 WIPER A ONLY WIPER B ONLY WIPERS A AND B 写保护(WP) 写保护特性可以防止 EEPROM 被意外重写。WP 端接 VDD 或开路将会阻止任何对 EEPROM 的写操作。当 WP = 1 时， 对易失寄存器(VREG)进行写操作，将使用储存在非易失 寄存器(NVREG)内的受保护数据对抽头的位置进行更新。 WP 接地将会允许对 EEPROM 的写入，用来自 EEPROM 或直接来自 I2C (表 2)接口的数据更新滑动端位置。WP 接 GND 会使供电电流增加 19.6µA (最大)。 为确保失效保护、写保护功能，在 WP 上拉至高电平以前， 将受保护数据写入非易失寄存器和易失寄存器。如果释 放 WP (WP = 0)，并发送部分指令或无效的 I2C 指令(例如 ______________________________________________________________________________________ 11 MAX5477/MAX5478/MAX5479 表2. VREG和NVREG的写保护动作 单字节轮询)，会将移位寄存器的数据装载到易失寄存器 内，进而改变抽头位置。在从写保护(WP = 1)状态转换到 非写保护 (WP = 0) 状态时，最好使用有效的 3 字节 I2C 命 令进行正确的操作。 SDA 串行寻址 作为从设备从 I2C/SMBusTM MAX5477/MAX5478/MAX5479 兼容的 2 线串行接口接收数据。该接口采用串行数据线 (SDA)和串行时钟线(SCL)实现主、从设备间的双向通信。 主设备，通常是微控制器，启动对 MAX5477/MAX5478/ MAX5479 的全部数据传输，并产生 SCL 时钟来同步数据 传输(见图 1)。 MAX5477/MAX5478/MAX5479 的 SDA 可作为输入或漏极 开路输出。 SDA 线上需要一个典型值为 4.7kΩ 的上拉电 阻。MAX5477/MAX5478/MAX5479 的 SCL 只能作为输入 端。若 2 线接口挂接有多个主机，或者单主机系统 SCL 输 出为漏极开路， SCL 线上需接典型值为 4.7kΩ 的上拉电 阻。在混合电压系统中，无论漏极驱动能力多大，SCL 和 SDA 都不应超过 VDD。 每次数据传输先由主机发送 START (S) 条件 ( 图 3) ，然后 发送 MAX5477/MAX5478/MAX5479 的 7 位从地址和 NOP/ W 位 (图 4)，一个命令字节和一个数据字节，最后是 STOP (P)条件 (图 3)。 START 和 STOP 条件 接口不工作时 SCL 和 SDA 均为高。主机发送 START 条件 开始数据传输，即 SCL 为高电平时 SDA 由高变低。当主 机完成与从机的通信后发送 STOP 条件，即在 SCL 为高电 平时 SDA 由低变高。然后释放总线，进行其它的传输 (图 3)。 SDA 0 START MSB 1 0 1 SCL S P START CONDITION STOP CONDITION 图 3. START 和 STOP 条件 位传输 每个时钟传输一个数据位。 SCL 为高时， SDA 上的数据 必须保持稳定( 图 5)。 应答信号 应答信号是时钟第 9 位，它是接收端收到每个数据字节后 的握手应答信号( 图 6)。因此，每个字节的有效传输需要 9 位。主机产生第 9 个时钟脉冲，接收端在应答时钟脉冲 内将 SDA 拉低，所以，在时钟脉冲为高电平期间 SDA 必 须稳定在低电平。 从地址 具有 位长的从地址 MAX5477/MAX5478/MAX5479 7 ( 图 4)。紧随 7 位从地址的第 8 位是 NOP/W 位。NOP/ W 位 置低表示写操作，置高表示空操作。 A2 A1 A0 NOP/W LSB SCL 图 4. 从地址 SMBus 是 Intel Corporation 的商标。 12 ______________________________________________________________________________________ ACK MAX5477/MAX5478/MAX5479 MAX5477/MAX5478/MAX5479 双路、256抽头、非易失、 I2C接口、数字电位器 双路、256抽头、非易失、 I2C接口、数字电位器 SDA MAX5477/MAX5478/MAX5479 CLOCK PULSE FOR ACKNOWLEDGMENT START CONDITION SCL 1 2 8 9 NOT ACKNOWLEDGE SCL SDA DATA STABLE, DATA VALID CHANGE OF DATA ALLOWED ACKNOWLEDGE 图 5. 位传输 图 6. 应答信号 D15 COMMAND BYTE IS STORED ON RECEIPT OF STOP CONDITION D14 D13 D12 D11 D10 D9 D8 ACKNOWLEDGE FROM MAX5477/MAX5478/MAX5479 S SLAVE ADDRESS 0 COMMAND BYTE A A P ACKNOWLEDGE FROM MAX5477/MAX5478/MAX5479 NOP/W 图 7. 接收命令字节 ACKNOWLEDGE FROM MAX5477/MAX5478/MAX5479 HOW CONTROL BYTE AND DATA BYTE MAP INTO MAX5477/MAX5478/MAX5479 REGISTERS D15 D14 D13 D12 D11 D10 D9 ACKNOWLEDGE FROM MAX5477/MAX5478/MAX5479 D8 D7 D6 D5 D4 D3 D2 D1 D0 ACKNOWLEDGE FROM MAX5477/MAX5478/MAX5479 S SLAVE ADDRESS 0 A COMMAND BYTE NOP/W A DATA BYTE A P 1 BYTE 图 8. 接收命令和单数据字节 MAX5477/MAX5478/MAX5479 提供三个地址输入(A0， A1 和 A2 )，最多允许 8 个器件共享一个公共总线(表 1 )。 MAX5477/MAX5478/MAX5479 的从地址高 4 位(MSB) 总 是 0101。A2、A1 和 A0 设置从地址其余的 3 位。将每个地 址输入端接 V DD 或 GND 来设置这 3 位。每个器件必须具 有唯一的地址来共享公共总线。 写数据格式 向 MAX5477/MAX5478/MAX5479 写入数据时，器件从地 址的 NOP/ W (第 8 位)置零，后面跟至少 1 个字节的信息 (图 7 )。信息的第 1 个字节为命令字节。命令字节后面接 收的是数据字节。第 1 个数据字节写入由命令字节选择的 MAX5477/MAX5478/MAX5479 的内部寄存器(图 8) 。 命令字节 命令字节用于选择滑动端数据的源地址和目的地址(非易 失或易失存储寄存器) ，或者在非易失或易失存储寄存器 之间交换数据(见表 3)。 命令说明 VREG: 数据字节写入易失存储寄存器，滑动端位置更新 为易失存储寄存器中的数据。 NVREG: 数据字节写入非易失存储寄存器，滑动端位置 保持不变。 ______________________________________________________________________________________ 13 MAX5477/MAX5478/MAX5479 双路、256抽头、非易失、 I2C接口、数字电位器 5V 5V H_ 30V 30V W_ MAX5477 MAX5478 MAX5479 MAX480 H_ VOUT L_ MAX5477 MAX5478 MAX5479 MAX480 VOUT W_ L_ 图 10. 使用可变电阻实现正 LCD 偏置电压控制 图 9. 使用分压器实现正 LCD 偏置电压控制 NVREGxVREG: 数据从非易失存储寄存器传送到易失存 储寄存器(滑动端位置更新)。 VREGxNVREG: 数据从易失存储寄存器传送到非易失存 储寄存器(滑动端位置更新)。 非易失存储器 内置 EEPROM 包含一个 16 位非易失寄存器，保留断电前 写入的数据。非易失寄存器在工厂预置为中间值。非易 失存储器确保数据维持 50 年，可进行 200,000 次滑动端位 置写操作。写保护特性可以防止 EEPROM 的意外重写。 把 WP 接 VDD 或开路将使能写保护功能。滑动端寄存器只 会在 WP = VDD 时更新为 EEPROM 中的值。WP 接 GND 将 会允许对 EEPROM 的写操作，用 EEPROM 中的数据或直 接来自 I2C 接口的数据更新滑动端位置。 上电 上电时，MAX5477/MAX5478/MAX5479 将存储在非易失 存储寄存器的数据装入易失存储寄存器，并随之更新滑 动端位置。初始化周期需要 10µs。 待机 MAX5477/MAX5478/MAX5479 具有低功耗待机模式。器 件没有编程时，进入待机模式，电流消耗值降为 500nA (典型值 )。 ____________________________ 应用信息 MAX5477/MAX5478/MAX5479 适用于需要数控调节电阻的 电路，如 LCD 对比度调节(利用偏置电压调节显示器对比 度)，或用于增益和/或截止频率可调的可编程滤波器等。 14 LCD 正偏置电压控制 图 9 和图 10 展示了一个用 MAX5477/MAX5478/MAX5479 提供可调节的，正 LCD 偏置电压的应用。运算放大器提 供电阻分压电路的缓冲和放大，电阻分压电路可以由电 位器单独构成(图 9)，也可由一个固定电阻串联一个可变 电阻构成(图 10)。 可编程滤波器 图 11 为 MAX5477/MAX5478/MAX5479 用于一阶可编程 滤波器。滤波器的增益由 R 2 调节，截止频率通过 R 3 设 定。利用下式计算增益(A)和-3dB 截止频率(fC)： A = 1+ fC = R1 R2 1 2π × R 3 × C 失调电压和增益调节 将 MAX5477 的一个电位器的高低端分别连接在 MAX410 的 NULL 输入之间，滑动端接运放正电源，可在整个工作 温度范围内消除失调电压。将另一个电位器接入反馈回 路来调节 MAX410 的增益(图 12)。 可调电压基准 图 13 所示为 MAX5477/MAX5478/MAX5479 用作多级可调 电 压 基 准 中 的 反 馈 电 阻 。改 变 MAX5477/MAX5478/ MAX5479 滑动端的位置可以在 1.23V 至 VIN - 0.2V 之间独 立调节 MAX6160 的输出电压。 ______________________________________________________________________________________ 双路、256抽头、非易失、 I2C接口、数字电位器 V+ VIN R3 C MAX410 7 6 MAX410 R1 2 HB 4 R2 = RHL x D / 256 WHERE RHL = END-TO-END RESISTANCE AND = D DECIMAL VALUE OF WIPER CODE R1 HB WB R2 1 8 V- R2, R3 = RHL x D / 256 WHERE RHL = END-TO-END RESISTANCE AND D = DECIMAL VALUE OF WIPER CODE LA HA VOUT 3 MAX5477 MAX5478 MAX5479 1/2 MAX5477 WA LA HA MAX5477/MAX5478/MAX5479 5V WA 1/2 MAX5477 R2 WB LB LB 图 11. 可编程滤波器 图 12. 失调电压调节电路 5V IN V OUT1 OUT IN OUT 10kΩ FOR THE MAX5477 R 50kΩ VOUT_ = 1.23V x FOR THE MAX5478 R 100kΩ VOUT_ = 1.23V x FOR THE MAX5479 R VOUT_ = 1.23V x VOUT2 HB HA MAX6160 MAX6160 ADJ GND 1/2 MAX5477 1/2 MAX5478 1/2 MAX5479 WA R LA ADJ 1/2 MAX5477 1/2 MAX5478 1/2 MAX5479 WB R GND WHERE R = RHL x D / 256 AND D = DECIMAL VALUE OF WIPER CODE LB 图 13. 可调电压基准 _________________________________________芯片信息 TRANSISTOR COUNT: 12,651 PROCESS: BiCMOS _____________________________引脚配置 TOP VIEW VDD SCL N.C. HA WA LA 16 15 14 13 1 MAX5477 MAX5478 MAX5479 2 SDA 3 A0 4 HA 1 14 VDD 12 HB WA 2 13 SCL 11 WB LA 3 10 LB HB 4 MAX5477 MAX5478 MAX5479 WB 5 9 5 6 7 8 A1 A2 GND N.C. THIN QFN (3mm x 3mm) WP 12 SDA 11 A0 10 A1 LB 6 9 A2 WP 7 8 GND TSSOP (4.4mm x 5mm) ______________________________________________________________________________________ 15 _____________________________________________________________________________ 封装信息 (本数据资料提供的封装图可能不是最近的规格，如需最近的封装外型信息，请查询 www.maxim-ic.com.cn/packages。) (NE - 1) X e E MARKING 12x16L QFN THIN.EPS MAX5477/MAX5478/MAX5479 双路、256抽头、非易失、 I2C接口、数字电位器 E/2 D2/2 (ND - 1) X e AAAA D/2 e CL D D2 k CL b 0.10 M C A B E2/2 L E2 0.10 C CL CL 0.08 C A A2 A1 L L e e PACKAGE OUTLINE 8, 12, 16L THIN QFN, 3x3x0.8mm G 21-0136 PKG 12L 3x3 8L 3x3 16L 3x3 0.70 0.75 0.80 0.70 0.75 b 0.25 0.30 0.35 0.20 D 2.90 3.00 2.90 E e 2.90 3.00 3.10 0.65 BSC. 2.90 3.00 3.10 0.50 BSC. L 0.35 0.45 0.55 3.10 0.75 0.75 0.80 0.25 0.30 0.20 0.25 0.30 3.00 2.90 3.00 3.10 0.55 0.80 3.10 0.65 0.70 2.90 3.00 3.10 0.50 BSC. 0.30 0.40 N 8 12 16 ND 2 3 4 NE k 0 0.02 0.05 0.20 REF 0.25 0 0.02 0.50 4 3 2 A1 A2 0.05 0.20 REF 0.25 0 0.02 2 EXPOSED PAD VARIATIONS REF. MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. A 1 0.05 0.20 REF 0.25 PKG. CODES D2 MIN. NOM. TQ833-1 E2 MAX. MIN. NOM. MAX. PIN ID JEDEC DOWN BONDS ALLOWED 0.25 0.70 1.25 0.25 0.70 1.25 0.35 x 45° T1233-1 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEED-1 NO T1233-3 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEED-1 YES T1233-4 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEED-1 YES T1633-1 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEED-2 NO T1633-2 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEED-2 YES T1633F-3 0.65 0.80 0.95 0.65 0.80 0.95 0.225 x 45° WEED-2 N/A T1633FH-3 0.65 0.80 0.95 0.65 0.80 0.95 0.225 x 45° WEED-2 N/A T1633-4 0.95 1.10 1.25 0.95 1.10 1.25 0.35 x 45° WEED-2 NO WEEC NO NOTES: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES. N IS THE TOTAL NUMBER OF TERMINALS. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.20 mm AND 0.25 mm FROM TERMINAL TIP. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS. DRAWING CONFORMS TO JEDEC MO220 REVISION C. MARKING IS FOR PACKAGE ORIENTATION REFERENCE ONLY. NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY. PACKAGE OUTLINE 8, 12, 16L THIN QFN, 3x3x0.8mm 21-0136 16 G 2 2 ______________________________________________________________________________________ 双路、256抽头、非易失、 I2C接口、数字电位器 TSSOP4.40mm.EPS PACKAGE OUTLINE, TSSOP 4.40mm BODY 21-0066 G 1 1 MAXIM 北京办事处 北京 8328信箱 邮政编码 100083 免费电话：800 810 0310 电话：010-6211 5199 传真：010-6211 5299 Maxim不对Maxim产品以外的任何电路使用负责，也不提供其专利许可。Maxim保留在任何时间、没有任何通报的前提下修改产品资料和规格的权利。 Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 ___________________17 © 2006 Maxim Integrated Products Printed USA 是 Maxim Integrated Products, Inc. 的注册商标。 MAX5477/MAX5478/MAX5479 ___________________________________________________________________________封装信息(续 ) (本数据资料提供的封装图可能不是最近的规格，如需最近的封装外型信息，请查询 www.maxim-ic.com.cn/packages。) 19-3379; Rev 5; 11/11 KIT ATION EVALU E L B A IL AVA Dual, 256-Tap, Nonvolatile, Digital Potentiometers I2C-Interface, Features o Power-On Recall of Wiper Position from Nonvolatile Memory o EEPROM Write Protection o Tiny 3mm x 3mm x 0.8mm Thin QFN Package o 70ppm/°C End-to-End Resistance Temperature Coefficient o 10ppm/°C Ratiometric Temperature Coefficient o Fast 400kbps I2C-Compatible Serial Interface o 1µA (max) Static Supply Current o Single-Supply Operation: +2.7V to +5.25V o 256 Tap Positions per Potentiometer o ±0.5 LSB DNL in Voltage-Divider Mode o ±1 LSB INL in Voltage-Divider Mode Functional Diagram VDD GND HA 8-BIT SHIFT REGISTER 8 16-BIT LATCH 8 256 POSITION DECODER 256 WA POR SDA SCL I2C INTERFACE LA 16-BIT NV MEMORY WP Applications 8 256 WB MAX5477 MAX5478 MAX5479 A0 Mechanical Potentiometer Replacement Low-Drift Programmable-Gain Amplifiers Volume Control HB 256 POSITION DECODER A1 A2 LB Pin Configurations appear at end of data sheet. Liquid-Crystal Display (LCD) Contrast Control Ordering Information/Selector Guide PART TEMP RANGE PIN-PACKAGE 16 TQFN-EP* END-TO-END RESISTANCE (k) TOP MARK 10 ABO MAX5477ETE+T -40°C to +85°C MAX5477EUD+ -40°C to +85°C 14 TSSOP 10 — MAX5478ETE+T -40°C to +85°C 16 TQFN-EP* 50 ABP MAX5478EUD+ -40°C to +85°C 14 TSSOP 50 — MAX5479ETE+T -40°C to +85°C 16 TQFN-EP* 100 ABQ MAX5479EUD+ -40°C to +85°C 14 TSSOP 100 — +Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. *EP = Exposed pad. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX5477/MAX5478/MAX5479 General Description The MAX5477/MAX5478/MAX5479 nonvolatile, dual, linear-taper, digital potentiometers perform the function of a mechanical potentiometer, but replace the mechanics with a simple 2-wire digital interface. Each device performs the same function as a discrete potentiometer or variable resistor and has 256 tap points. The devices feature an internal, nonvolatile EEPROM used to store the wiper position for initialization during power-up. A write-protect feature prevents accidental overwrites of the EEPROM. The fast-mode I2C-compatible serial interface allows communication at data rates up to 400kbps, minimizing board space and reducing interconnection complexity in many applications. Three address inputs allow a total of eight unique address combinations. The MAX5477/MAX5478/MAX5479 provide three nominal resistance values: 10kΩ (MAX5477), 50kΩ (MAX5478), or 100kΩ (MAX5479). The nominal resistor temperature coefficient is 70ppm/°C end-to-end and 10ppm/°C ratiometric. The low temperature coefficient makes the devices ideal for applications requiring a lowtemperature-coefficient variable resistor, such as lowdrift, programmable gain-amplifier circuit configurations. The MAX5477/MAX5478/MAX5479 are available in 16pin 3mm x 3mm x 0.8mm TQFN and 14-pin 4.4mm x 5mm TSSOP packages. These devices operate over the extended -40°C to +85°C temperature range. MAX5477/MAX5478/MAX5479 Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers ABSOLUTE MAXIMUM RATINGS SDA, SCL, VDD to GND .........................................-0.3V to +6.0V All Other Pins to GND.................................-0.3V to (VDD + 0.3V) Maximum Continuous Current into H_, L_, and W_ MAX5477......................................................................±5.0mA MAX5478......................................................................±1.3mA MAX5479......................................................................±0.6mA Continuous Power Dissipation (TA = +70°C) 16-Pin TQFN (derate 17.5mW/°C above +70°C) .......1398mW 14-Pin TSSOP (derate 9.1mW/°C above +70°C) .........727mW Operating Temperature Range ...........................-40°C to +85°C Maximum Junction Temperature .....................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C Soldering Temperature (reflow) .......................................+260°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. PACKAGE THERMAL CHARACTERISTICS (Note 1) TQFN Junction-to-Ambient Thermal Resistance (θJA) ........57.2°C/W Junction-to-Case Thermal Resistance (θJC) ................40°C/W TSSOP Junction-to-Ambient Thermal Resistance (θJA) ......100.4°C/W Junction-to-Case Thermal Resistance (θJC) ................30°C/W Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial. ELECTRICAL CHARACTERISTICS (VDD = +2.7V to +5.25V, H_ = VDD, L_ = GND, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = +5V, TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DC PERFORMANCE (VOLTAGE-DIVIDER MODE) Resolution 256 Taps Integral Nonlinearity INL (Note 3) ±1 LSB Differential Nonlinearity DNL (Note 3) ±0.5 LSB ±1 LSB Dual Code Matching End-to-End Resistance Temperature Coefficient R0 and R1 set to same code (all codes) TCR Ratiometric Resistance Temperature Coefficient Full-Scale Error Zero-Scale Error 70 ppm/°C 10 ppm/°C MAX5477 -4 MAX5478 -0.6 MAX5479 -0.3 MAX5477 4 MAX5478 0.6 MAX5479 0.3 LSB LSB DC PERFORMANCE (VARIABLE-RESISTOR MODE) Integral Nonlinearity (Note 4) INL VDD = 3V ±3 VDD = 5V ±1.5 MAX5477 Differential Nonlinearity (Note 4) 2 DNL LSB ±1 MAX5478 ±1 MAX5479 ±1 _______________________________________________________________________________________ LSB Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers (VDD = +2.7V to +5.25V, H_ = VDD, L_ = GND, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = +5V, TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP R0 and R1 set to same code (all codes), VDD = 3V or 5V Dual Code Matching MAX UNITS ±3 LSB 675 DC PERFORMANCE (RESISTOR CHARACTERISTICS) Wiper Resistance RW Wiper Capacitance CW End-to-End Resistance RHL (Note 5) 325 10 pF MAX5477 7.5 10 12.5 MAX5478 37.5 50 62.5 MAX5479 75 100 125 k DIGITAL INPUTS VDD = 3.4V to 5.25V Input High Voltage (Note 6) VIH Input Low Voltage VIL (Note 6) Output Low Voltage VOL I SINK = 3mA WP Pullup Resistance IWP Input Leakage Current ILEAK 2.4 VDD < 3.4V V 0.7 x VDD 0.8 0.4 255 V k ±1 Input Capacitance V µA 5 pF HA = 1kHz (0 to VDD), LA = GND, LB = GND, measure WB -75 dB MAX5477 400 MAX5478 100 MAX5479 50 DYNAMIC CHARACTERISTICS Crosstalk 3dB Bandwidth (Note 7) Total Harmonic Distortion Plus Noise THD+N H_ = 1VRMS, f = 1kHz, L_ = GND, measure W_ kHz 0.003 % TA = +85°C 50 Years TA = +25°C 200,000 TA = +85°C 50,000 NONVOLATILE MEMORY RELIABILITY Data Retention Endurance Stores POWER SUPPLY Power-Supply Voltage VDD 2.70 Writing to EEPROM, digital inputs at GND or VDD, TA = +25°C (Note 8) Supply Current IDD Normal operation, digital inputs at GND or VDD, TA = +25°C 5.25 250 400 WP = GND 15 20.6 WP = VDD 0.5 1 V µA _______________________________________________________________________________________ 3 MAX5477/MAX5478/MAX5479 ELECTRICAL CHARACTERISTICS (continued) MAX5477/MAX5478/MAX5479 Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers TIMING CHARACTERISTICS (VDD = +2.7V to +5.25V, H_ = VDD, L_ = GND, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VDD = +5V, TA = +25°C. See Figure 1.) (Notes 9 and 10) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS ANALOG SECTION MAX5477 Wiper Settling Time (Note 11) tWS 325 MAX5478 500 MAX5479 1000 ns DIGITAL SECTION SCL Clock Frequency f SCL 400 kHz Setup Time for START Condition t SU:STA 0.6 µs Hold Time for START Condition tHD:STA 0.6 µs SCL High Time tHIGH 0.6 µs SCL Low Time tLOW 1.3 µs Data Setup Time t SU:DAT 100 ns Data Hold Time tHD:DAT 0 0.9 µs SDA, SCL Rise Time tR 300 ns SDA, SCL Fall Time tF 300 ns Setup Time for STOP Condition t SU:STO Bus Free Time Between STOP and START Condition tBUF Pulse Width of Spike Suppressed t SP Capacitive Load for Each Bus Line CB Write NV Register Busy Time Minimum power-up rate = 0.2V/µs 0.6 µs 1.3 µs 50 ns (Note 12) 400 pF (Note 13) 12 ms Note 2: All devices are production tested at TA = +25°C and are guaranteed by design and characterization for -40°C < TA < +85°C. Note 3: The DNL and INL are measured with the potentiometer configured as a voltage-divider with H_ = VDD and L_ = GND. The wiper terminal is unloaded and measured with a high-input-impedance voltmeter. Note 4: The DNL and INL are measured with the potentiometer configured as a variable resistor. H_ is unconnected and L_ = GND. For VDD = +5V, the wiper is driven with 400µA (MAX5477), 80µA (MAX5478), or 40µA (MAX5479). For VDD = +3V, the wiper is driven with 200µA (MAX5477), 40µA (MAX5478), or 20µA (MAX5479). Note 5: The wiper resistance is measured using the source currents given in Note 3. Note 6: The devices draw current in excess of the specified supply current when the digital inputs are driven with voltages between (VDD - 0.5V) and (GND + 0.5V). See Supply Current vs. Digital Input Voltage in the Typical Operating Characteristics. Note 7: Wiper at midscale with a 10pF load (DC measurement). L_ = GND, an AC source is applied to H_, and the W_ output is measured. A 3dB bandwidth occurs when the AC W_/H_ value is 3dB lower than the DC W_/H_ value. Note 8: The programming current exists only during power-up and EEPROM writes. Note 9: The SCL clock period includes rise and fall times (tR = tF). All digital input signals are specified with tR = tF = 2ns and timed from a voltage level of (VIL + VIH) / 2. Note 10: Digital timing is guaranteed by design and characterization, and is not production tested. Note 11: This is measured from the STOP pulse to the time it takes the output to reach 50% of the output step size (divider mode). It is measured with a maximum external capacitive load of 10pF. Note 12: An appropriate bus pullup resistance must be selected depending on board capacitance. Refer to the I2C-bus specification document linked to this web address: www.semiconductors.philips.com/acrobat/literature/9398/39340011.pdf Note 13: The idle time begins from the initiation of the STOP pulse. 4 _______________________________________________________________________________________ Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers SUPPLY CURRENT vs. TEMPERATURE 0.6 VCC = 5V 0.4 VCC = 3V WP = GND VCC = 5V 13 11 9 0.2 7 0 5 VCC = 3V 500 MAX5477/78/79 toc02 SUPPLY CURRENT (µA) 0.8 15 MAX5477/78/79 toc1a WP = VDD SUPPLY CURRENT (µA) MAX5477/78/79 toc01 1.0 WIPER RESISTANCE vs. INPUT CODE 450 400 WIPER RESISTANCE (Ω) SUPPLY CURRENT vs. TEMPERATURE (MAX5477) 350 300 250 200 150 100 50 -40 -15 10 35 60 0 -40 85 -15 10 35 60 85 TEMPERATURE (°C) TEMPERATURE (°C) MAX5477 CL = 10pF H_ = VDD FROM TAP 00 TO TAP 04 SDA 2V/div W_ 20mV/div MAX5478 CL = 10pF H_ = VDD FROM TAP 00 TO TAP 04 MAX5479 CW_ = 10pF H_ = VDD FROM TAP 00 TO TAP 04 WIPER TRANSIENT AT POWER-ON MAX5477/78/79 toc07 MAX5477/78/79 toc06 W_ 20mV/div 400ns/div WIPER TRANSIENT AT POWER-ON WIPER TRANSIENT AT POWER-ON 128 160 192 224 256 MAX5477/78/79 toc05 1µs/div 200ns/div 96 SDA 2V/div SDA 2V/div W_ 50mV/div 64 TAP-TO-TAP SWITCHING TRANSIENT MAX5477/78/79 toc04 MAX5477/78/79 toc03 32 INPUT CODE TAP-TO-TAP SWITCHING TRANSIENT TAP-TO-TAP SWITCHING TRANSIENT 0 VDD 2V/div MAX5477/78/79 toc08 VDD 2V/div VDD 2V/div W_ 1V/div W_ 1V/div W_ 1V/div 2µs/div MAX5479 TAP = 128 MAX5478 TAP = 128 MAX5477 TAP = 128 4µs/div 2µs/div _______________________________________________________________________________________ MAX5477/MAX5478/MAX5479 Typical Operating Characteristics (VDD = +5V, H_ = VDD, L_ = GND, TA = +25°C, unless otherwise noted.) 5 Typical Operating Characteristics (continued) (VDD = +5V, H_ = VDD, L_ = GND, TA = +25°C, unless otherwise noted.) 0.2 MAX5478 0.2 0.1 0.15 0.05 INL (LSB) 0.20 0.10 0 -0.1 -0.2 -0.2 32 64 96 -0.3 0 128 160 192 224 256 32 64 96 0 128 160 192 224 256 32 64 96 128 160 192 224 256 CODE CODE CODE DIFFERENTIAL NONLINEARITY vs. CODE (VDM MODE) INTEGRAL NONLINEARITY vs. CODE (VRM MODE) DIFFERENTIAL NONLINEARITY vs. CODE (VRM MODE) MAX5478 0.2 MAX5478 0.10 0.2 0.04 0.02 DNL (LSB) INL (LSB) 0 0 0 -0.02 -0.1 -0.1 -0.2 -0.2 -0.3 -0.3 MAX5478 0.08 0.06 0.1 0.1 MAX5477/78/79 toc14 0.3 MAX5477/78/79 toc12 0.3 MAX5477/78/79 toc13 0 0 -0.1 -0.3 0 DNL (LSB) 0.3 0.1 DNL (LSB) INL (LSB) 0.25 MAX5477 MAX5477/78/79 toc11 0.30 0.3 MAX5477/78/79 toc10 MAX5477 MAX5477/78/79 toc09 0.35 INTEGRAL NONLINEARITY vs. CODE (VDM MODE) DIFFERENTIAL NONLINEARITY vs. CODE (VDM MODE) INTEGRAL NONLINEARITY vs. CODE (VDM MODE) -0.04 -0.06 -0.08 32 64 96 32 64 96 128 160 192 224 256 64 96 128 160 192 224 256 INTEGRAL NONLINEARITY vs. CODE (VDM MODE) DIFFERENTIAL NONLINEARITY vs. CODE (VDM MODE) INTEGRAL NONLINEARITY vs. CODE (VRM MODE) 0 -0.04 -0.08 -0.12 -0.16 -0.20 64 96 128 160 192 224 256 CODE 0.20 MAX5477/78/79 toc17 MAX5479 DNL (LSB) 0.04 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0 -0.02 -0.04 -0.06 -0.08 -0.10 -0.12 -0.14 MAX5479 0.16 0.12 0.08 INL (LSB) MAX5477/78/79 toc15 0.08 32 32 CODE MAX5479 0 0 CODE 0.12 6 0 128 160 192 224 256 CODE 0.20 0.16 -0.10 MAX5477/78/79 toc16 0 INL (LSB) MAX5477/MAX5478/MAX5479 Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers 0.04 0 -0.04 -0.08 -0.12 -0.16 -0.20 0 32 64 96 128 160 192 224 256 0 32 64 96 CODE _______________________________________________________________________________________ 128 160 192 224 256 CODE Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers 0 -0.04 -20 -40 -50 -60 -30 -40 -50 -60 -0.08 -70 -70 -0.12 -80 -80 -0.16 -90 -90 -0.20 -100 -100 32 64 96 128 160 192 224 256 0.1 1 10 100 1000 FREQUENCY (kHz) CODE CROSSTALK vs. FREQUENCY (MAX5479) -20 CW_ = 10pF 0 -1 GAIN (dB) -50 -60 CW_ = 50pF -3 -4 -2 -3 -4 -6 -7 -7 -100 -8 -8 10 100 1000 10,000 0.1 1 FREQUENCY (kHz) MIDSCALE WIPER RESPONSE vs. FREQUENCY (MAX5479) 1 1 10 100 1000 FREQUENCY (kHz) 1 MIDSCALE TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY (MAX5478) 10 MIDSCALE 1 THD+N (%) 0.1 THD+N (%) GAIN (dB) 0 0.1 1000 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY (MAX5477) MAX5477/78/79 toc24 2 10 100 FREQUENCY (kHz) MAX5477/78/79 toc25 1 CW_ = 50pF -5 -90 0.1 CW_ = 10pF 0 -6 -80 1000 -1 -5 -70 100 1 -2 -40 10 2 GAIN (dB) CROSSTALK (dB) -30 1 MIDSCALE WIPER RESPONSE vs. FREQUENCY (MAX5478) 1 MAX5477/78/79 toc21 CW_ = 10pF 0.1 FREQUENCY (kHz) MIDSCALE WIPER RESPONSE vs. FREQUENCY (MAX5477) 0 -10 0.01 10,000 MAX5477/78/79 toc22 0 MAX5477/78/79 toc26 0.04 CW_ = 10pF -10 CROSSTALK (dB) -30 MAX5477/78/79 toc20 -20 CROSSTALK (dB) 0.08 CW_ = 10pF -10 0 MAX5477/78/79 toc19 MAX5479 0.12 DNL (LSB) 0 MAX5477/78/79 toc18 0.20 0.16 CROSSTALK vs. FREQUENCY (MAX5478) CROSSTALK vs. FREQUENCY (MAX5477) MAX5477 toc23 DIFFERENTIAL NONLINEARITY vs. CODE (VRM MODE) -1 -2 CW_ = 10pF -3 0.1 0.01 0.01 0.001 -4 CW_ = 50pF 0.0001 0.001 -5 0.1 1 10 FREQUENCY (kHz) 100 1000 0.01 0.1 1 10 FREQUENCY (kHz) 100 0.01 0.1 1 10 100 FREQUENCY (kHz) _______________________________________________________________________________________ 7 MAX5477/MAX5478/MAX5479 Typical Operating Characteristics (continued) (VDD = +5V, H_ = VDD, L_ = GND, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VDD = +5V, H_ = VDD, L_ = GND, TA = +25°C, unless otherwise noted.) 0.1 0.01 0.001 0.0001 0.4 0.2 0 -0.2 -0.4 -0.6 0.1 1 10 100 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 -15 -40 FREQUENCY (kHz) 10 35 60 -40 85 -15 0.3 0.2 0.1 0 -0.1 -0.2 600 550 500 SUPPLY CURRENT (µA) 0.4 35 SUPPLY CURRENT vs. DIGITAL INPUT VOLTAGE MAX5477/78/79 toc30 0.5 10 TEMPERATURE (°C) TEMPERATURE (°C) END-TO-END RESISTANCE % CHANGE vs. TEMPERATURE (MAX5479) END-TO-END RESISTANCE CHANGE (%) 0.4 MAX5477/78/79 toc31 0.01 WP = GND 450 400 350 300 250 200 -0.3 150 100 -0.4 50 VCC = 5V VCC = 3V 0 -0.5 -40 -15 10 35 TEMPERATURE (°C) 8 0.5 END-TO-END RESISTANCE CHANGE (%) 1 END-TO-END RESISTANCE CHANGE (%) MIDSCALE MAX5477/78/79 toc28 0.6 MAX5477/78/79 toc27 10 END-TO-END RESISTANCE % CHANGE vs. TEMPERATURE (MAX5478) END-TO-END RESISTANCE % CHANGE vs. TEMPERATURE (MAX5477) MAX5477/78/79 toc29 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY (MAX5479) THD+N (%) MAX5477/MAX5478/MAX5479 Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers 60 85 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 DIGITAL INPUT VOLTAGE (V) _______________________________________________________________________________________ 60 85 Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers PIN NAME FUNCTION TSSOP THIN QFN 1 15 HA Potentiometer A High Terminal 2 14 WA Potentiometer A Wiper Terminal 3 13 LA Potentiometer A Low Terminal 4 12 HB Potentiometer B High Terminal 5 11 WB Potentiometer B Wiper Terminal 6 10 LB Potentiometer B Low Terminal 7 9 WP Write-Protect Input. Connect to GND to allow changes to the wiper position and the data stored in the EEPROM. Connect to VDD or leave unconnected to enable the write protection of the EEPROM. See the Write Protect (WP) section for operating instructions. 8 7 GND 9 6 A2 Address Input 2. Connect to VDD or GND (see Table 1). 10 5 A1 Address Input 1. Connect to VDD or GND (see Table 1). 11 4 A0 12 3 SDA Address Input 0. Connect to VDD or GND (see Table 1). I2C Serial Data 13 2 SCL I2C Clock Input 14 1 VDD Power-Supply Input. Connect a +2.7V to +5.25V power supply to VDD and bypass VDD to GND with a 0.1µF capacitor installed as close to the device as possible. — 8, 16 N.C. No Connection. Do not connect. — EP EP Ground Exposed Paddle. Do not connect. SDA tBUF tSU:DAT tSU:STA tHD:DAT tLOW tHD:STA tSU:STO SCL tHIGH tHD:STA tR tF START CONDITION (S) REPEATED START CONDITION (SR) ACKNOWLEDGE (A) STOP CONDITION (P) START CONDITION (S) PARAMETERS ARE MEASURED FROM 30% TO 70%. Figure 1. I2C Serial-Interface Timing Diagram _______________________________________________________________________________________ 9 MAX5477/MAX5478/MAX5479 Pin Description MAX5477/MAX5478/MAX5479 Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers Detailed Description The MAX5477/MAX5478/MAX5479 contain two resistor arrays with 255 elements in each array. The MAX5477 has a total end-to-end resistance of 10kΩ, the MAX5478 has an end-to-end resistance of 50kΩ, and the MAX5479 has an end-to-end resistance of 100kΩ. The MAX5477/MAX5478/MAX5479 provide access to the high, low, and wiper terminals for a standard voltage-divider configuration. Connect H_, L_, and W_ in any desired configuration as long as their voltages remain between GND and VDD. A simple 2-wire I2C-compatible serial interface moves the wiper among the 256 tap points (Figure 2). A nonvolatile memory stores the wiper position and recalls the stored wiper position upon power-up. The nonvolatile memory is guaranteed for 50 years for wiper data retention and up to 200,000 wiper store cycles. Analog Circuitry The MAX5477/MAX5478/MAX5479 consist of two resistor arrays with 255 resistive elements; 256 tap points are accessible to the wipers, along the resistor string between H_ and L_. The wiper tap point is selected by programming the potentiometer through the I2C interface. An address byte, a command byte, and 8 data bits program the wiper position for each potentiometer. The H_ and L_ terminals of the MAX5477/MAX5478/ MAX5479 are similar to the two end terminals of a mechanical potentiometer. The MAX5477/MAX5478/ MAX5479 feature power-on reset circuitry that loads the wiper position from the nonvolatile memory at power-up. Table 1. Slave Addresses ADDRESS INPUTS H_ SLAVE ADDRESS A2 A1 A0 GND GND GND 0101000 GND GND VDD 0101001 GND VDD GND 0101010 GND VDD VDD 0101011 VDD GND GND 0101100 VDD GND VDD 0101101 VDD VDD GND 0101110 VDD VDD VDD 0101111 S256 R255 S255 R254 S254 RW 256-POSITION DECODER W_ S3 R2 WIPER CODE 02h S2 R1 S1 L_ Figure 2. Potentiometer Configuration 10 ______________________________________________________________________________________ Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers COMMAND WP = 0 WP = 1 I2C data is written to VREG. Wiper position updates with I2C data. No change to NVREG. Copy NVREG to VREG. Wiper position updates with NVREG data. No change to NVREG. Write to NVREG No change to VREG or wiper position. I2C data is written to NVREG. No change to VREG or wiper position. No change to NVREG. Copy NVREG to VREG Copy NVREG to VREG. Wiper position updates with NVREG data. No change to NVREG. Copy NVREG to VREG. Wiper position updates with NVREG data. No change to NVREG. Copy VREG to NVREG Copy VREG to NVREG. No change to VREG or wiper position. No change to VREG or wiper position. No change to NVREG. Write to VREG Table 3. Command Byte Summary ADDRESS BYTE 1 SCL CYCLE NUMBER 2 3 4 5 6 7 COMMAND BYTE 8 START (S) A6 A5 A4 A3 A2 A1 A0 9 DATA BYTE 10 11 12 13 14 15 16 17 18 ACK (A) 19 20 21 22 23 24 25 26 27 ACK ACK TX NV V R3 R2 R1 R0 D7 D6 D5 D4 D3 D2 D1 D0 (A) (A) VREG 0 1 0 1 A2 A1 A0 0 0 0 0 1 0 0 0 1 NVREG 0 1 0 1 A2 A1 A0 0 0 0 1 0 0 0 0 1 D7 D6 D5 D4 D3 D2 D1 D0 NVREGxVREG 0 1 0 1 A2 A1 A0 0 0 1 1 0 0 0 0 1 D7 D6 D5 D4 D3 D2 D1 D0 VREGxNVREG 0 1 0 1 A2 A1 A0 0 0 1 0 1 0 0 0 1 D7 D6 D5 D4 D3 D2 D1 D0 VREG 0 1 0 1 A2 A1 A0 0 0 0 0 1 0 0 1 0 D7 D6 D5 D4 D3 D2 D1 D0 NVREG 0 1 0 1 A2 A1 A0 0 0 0 1 0 0 0 1 0 D7 D6 D5 D4 D3 D2 D1 D0 NVREGxVREG 0 1 0 1 A2 A1 A0 0 0 1 1 0 0 0 1 0 D7 D6 D5 D4 D3 D2 D1 D0 VREGxNVREG 0 1 0 1 A2 A1 A0 0 0 1 0 1 0 0 1 0 D7 D6 D5 D4 D3 D2 D1 D0 VREG 0 1 0 1 A2 A1 A0 0 0 0 0 1 0 0 1 1 D7 D6 D5 D4 D3 D2 D1 D0 NVREG 0 1 0 1 A2 A1 A0 0 0 0 1 0 0 0 1 1 D7 D6 D5 D4 D3 D2 D1 D0 NVREGxVREG 0 1 0 1 A2 A1 A0 0 0 1 1 0 0 0 1 1 D7 D6 D5 D4 D3 D2 D1 D0 VREGxNVREG 0 1 0 1 A2 A1 A0 0 0 1 0 1 0 0 1 1 D7 D6 D5 D4 D3 D2 D1 D0 STOP NOTES (P) D7 D6 D5 D4 D3 D2 D1 D0 WIPER A ONLY WIPER B ONLY WIPERS A AND B Digital Interface Write Protect (WP) The MAX5477/MAX5478/MAX5479 feature an internal, nonvolatile EEPROM that stores the wiper state for initialization during power-up. The shift register decodes the command and address bytes, routing the data to the proper memory registers. Data written to a volatile memory register immediately updates the wiper position, or writes data to a nonvolatile register for storage (see Table 3). A write-protect feature prevents accidental overwriting of the EEPROM. Connect WP to VDD or leave unconnected to prevent any EEPROM write cycles. Writing to the volatile register (VREG) while WP = 1 updates the wiper position with the protected data stored in the nonvolatile register (NVREG). Connect WP to GND to allow write commands to the EEPROM and to update the wiper position from either the value in the EEPROM or directly from the I2C interface (Table 2). Connecting WP to GND increases the supply current by 19.6µA (max). To ensure a fail-safe, write-protect feature, write the data to be protected to both the nonvolatile and volatile registers before pulling WP high. Releasing WP (WP = 0) and sending partial or invalid I2C commands (such as single-byte address polling) can load the volatile The volatile register retains data as long as the device is powered. Removing power clears the volatile register. The nonvolatile register retains data even after power is removed. Upon power-up, the power-on reset circuitry controls the transfer of data from the nonvolatile register to the volatile register. ______________________________________________________________________________________ 11 MAX5477/MAX5478/MAX5479 Table 2. Write-Protect Behavior of VREG and NVREG MAX5477/MAX5478/MAX5479 Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers register with input shift register data and change the wiper position. Use valid 3-byte I 2C commands for proper operation. This precautionary operation is necessary only when transitioning from write protected (WP = 1) to not write protected (WP = 0). Serial Addressing The MAX5477/MAX5478/MAX5479 operate as slave devices that send and receive data through an I2C-/ SMBus™-compatible 2-wire serial interface. The interface uses a serial data access (SDA) line and a serial clock line (SCL) to achieve bidirectional communication between master(s) and slave(s). A master, typically a microcontroller, initiates all data transfers to the MAX5477/MAX5478/MAX5479, and generates the SCL clock that synchronizes the data transfer (Figure 1). The MAX5477/MAX5478/MAX5479 SDA line operates as both an input and an open-drain output. The SDA line requires a pullup resistor, typically 4.7kΩ. The MAX5477/MAX5478/MAX5479 SCL line operates only as an input. The SCL line requires a pullup resistor (typically 4.7kΩ) if there are multiple masters on the 2-wire interface, or if the master in a single-master system has an open-drain SCL output. SCL and SDA should not exceed VDD in a mixed-voltage system, despite the open-drain drivers. Each transmission consists of a START (S) condition (Figure 3) sent by a master, followed by the MAX5477/MAX5478/MAX5479 7-bit slave address plus the NOP/W bit (Figure 4), 1 command byte and 1 data byte, and finally a STOP (P) condition (Figure 3). START and STOP Conditions Both SCL and SDA remain high when the interface is not busy. A master controller signals the beginning of a transmission with a START condition by transitioning SDA from high to low while SCL is high. The master controller issues a STOP condition by transitioning the SDA from low to high while SCL is high, when it finishes SDA 0 START 1 MSB 0 1 SDA SCL S P START CONDITION STOP CONDITION Figure 3. START and STOP Conditions communicating with the slave. The bus is then free for another transmission (Figure 3). Bit Transfer One data bit is transferred during each clock pulse. The data on the SDA line must remain stable while SCL is high (Figure 5). Acknowledge The acknowledge bit is a clocked 9th bit that the recipient uses to handshake receipt of each byte of data (Figure 6). Thus, each byte transferred effectively requires 9 bits. The master controller generates the 9th clock pulse, and the recipient pulls down SDA during the acknowledge clock pulse, so the SDA line remains stable low during the high period of the clock pulse. Slave Address The MAX5477/MAX5478/MAX5479 have a 7-bit-long slave address (Figure 4). The 8th bit following the 7-bit slave address is the NOP/W bit. Set the NOP/W bit low for a write command and high for a no-operation command. The MAX5477/MAX5478/MAX5479 provide three address inputs (A0, A1, and A2), allowing up to eight devices to share a common bus (Table 1). The first 4 bits (MSBs) of the MAX5477/MAX5478/MAX5479 slave addresses are always 0101. A2, A1, and A0 set the next A2 A1 A0 NOP/W LSB SCL Figure 4. Slave Address SMBus is a trademark of Intel Corporation. 12 ______________________________________________________________________________________ ACK Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers SDA MAX5477/MAX5478/MAX5479 CLOCK PULSE FOR ACKNOWLEDGMENT START CONDITION SCL 1 2 8 9 NOT ACKNOWLEDGE SCL SDA DATA STABLE, DATA VALID CHANGE OF DATA ALLOWED ACKNOWLEDGE Figure 5. Bit Transfer Figure 6. Acknowledge D15 COMMAND BYTE IS STORED ON RECEIPT OF STOP CONDITION D14 D13 D12 D11 D10 D9 D8 ACKNOWLEDGE FROM MAX5477/MAX5478/MAX5479 S SLAVE ADDRESS 0 COMMAND BYTE A A P ACKNOWLEDGE FROM MAX5477/MAX5478/MAX5479 NOP/W Figure 7. Command Byte Received ACKNOWLEDGE FROM MAX5477/MAX5478/MAX5479 HOW CONTROL BYTE AND DATA BYTE MAP INTO MAX5477/MAX5478/MAX5479 REGISTERS D15 D14 D13 D12 D11 D10 D9 ACKNOWLEDGE FROM MAX5477/MAX5478/MAX5479 D8 D7 D6 D5 D4 D3 D2 D1 D0 ACKNOWLEDGE FROM MAX5477/MAX5478/MAX5479 S SLAVE ADDRESS 0 A COMMAND BYTE NOP/W A DATA BYTE A P 1 BYTE Figure 8. Command and Single Data Byte Received 3 bits in the slave address. Connect each address input to VDD or GND to set these 3 bits. Each device must have a unique address to share a common bus. Message Format for Writing Write to the MAX5477/MAX5478/MAX5479 by transmitting the device’s slave address with NOP/W (8th bit) set to zero, followed by at least 1 byte of information (Figure 7). The 1st byte of information is the command byte. The bytes received after the command byte are the data bytes. The 1st data byte goes into the internal register of the MAX5477/MAX5478/MAX5479 as selected by the command byte (Figure 8). Command Byte Use the command byte to select the source and destination of the wiper data (nonvolatile or volatile memory registers) and swap data between nonvolatile and volatile memory registers (see Table 3). Command Descriptions VREG: The data byte writes to the volatile memory register and the wiper position updates with the data in the volatile memory register. NVREG: The data byte writes to the nonvolatile memory register. The wiper position is unchanged. NVREGxVREG: Data transfers from the nonvolatile memory register to the volatile memory register (wiper position updates). ______________________________________________________________________________________ 13 MAX5477/MAX5478/MAX5479 Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers 5V 5V H_ 30V 30V W_ MAX5477 MAX5478 MAX5479 MAX480 H_ VOUT L_ MAX5477 MAX5478 MAX5479 MAX480 VOUT W_ L_ Figure 9. Positive LCD Bias Control Using a Voltage-Divider VREGxNVREG: Data transfers from the volatile memory register into the nonvolatile memory register. Nonvolatile Memory The internal EEPROM consists of a 16-bit nonvolatile register that retains the value written to it prior to power down. The nonvolatile register is programmed with the midscale value at the factory. The nonvolatile memory is guaranteed for 50 years for wiper position retention and up to 200,000 wiper write cycles. A write-protect feature prevents accidental overwriting of the EEPROM. Connect WP to VDD or leave open to enable the writeprotect feature. The wiper position only updates with the value in the EEPROM when WP = VDD. Connect WP to GND to allow EEPROM write cycles and to update the wiper position from nonvolatile memory or directly from the I2C serial interface. Power-Up Upon power-up, the MAX5477/MAX5478/MAX5479 load the data stored in the nonvolatile memory register into the volatile memory register, updating the wiper position with the data stored in the nonvolatile memory register. This initialization period takes 10µs. Standby The MAX5477/MAX5478/MAX5479 feature a low-power standby mode. When the device is not being programmed, it enters into standby mode and supply current drops to 500nA (typ). Applications Information The MAX5477/MAX5478/MAX5479 are ideal for circuits requiring digitally controlled adjustable resistance, such as LCD contrast control (where voltage biasing adjusts the display contrast), or for programmable filters with adjustable gain and/or cutoff frequency. 14 Figure 10. Positive LCD Bias Control Using a Variable Resistor Positive LCD Bias Control Figures 9 and 10 show an application where the MAX5477/MAX5478/MAX5479 provide an adjustable, positive LCD bias voltage. The op amp provides buffering and gain to the resistor-divider network made by the potentiometer (Figure 9) or by a fixed resistor and a variable resistor (see Figure 10). Programmable Filter Figure 11 shows the MAX5477/MAX5478/MAX5479 in a 1st-order programmable application filter. Adjust the gain of the filter with R2, and set the cutoff frequency with R3. Use the following equations to calculate the gain (A) and the -3dB cutoff frequency (fC): R1 R2 1 fC = 2π × R 3 × C A = 1+ Offset Voltage and Gain Adjustment Connect the high and low terminals of one potentiometer of a MAX5477 between the NULL inputs of a MAX410 and the wiper to the op amp’s positive supply to nullify the offset voltage over the operating temperature range. Install the other potentiometer in the feedback path to adjust the gain of the MAX410 (Figure 12). Adjustable Voltage Reference Figure 13 shows the MAX5477/MAX5478/MAX5479 used as the feedback resistors in multiple adjustable voltage reference applications. Independently adjust the output voltages of the MAX6160 parts from 1.23V to V IN - 0.2V by changing the wiper positions of the MAX5477/MAX5478/MAX5479. ______________________________________________________________________________________ Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers V+ VIN R3 C 1/2 MAX5477 WA LA HA MAX5477/MAX5478/MAX5479 5V WA MAX410 LA HA VOUT 7 3 1 8 MAX5477 MAX5478 MAX5479 VR1 2 4 HB R2, R3 = RHL x D / 256 WHERE RHL = END-TO-END RESISTANCE AND D = DECIMAL VALUE OF WIPER CODE R2 = RHL x D / 256 WHERE RHL = END-TO-END RESISTANCE AND = D DECIMAL VALUE OF WIPER CODE R1 HB WB R2 6 MAX410 1/2 MAX5477 R2 WB LB LB Figure 11. Programmable Filter Figure 12. Offset Voltage Adjustment Circuit 5V IN IN V OUT1 OUT OUT 10kΩ FOR THE MAX5477 R 50kΩ VOUT_ = 1.23V x FOR THE MAX5478 R 100kΩ VOUT_ = 1.23V x FOR THE MAX5479 R VOUT_ = 1.23V x VOUT2 HB HA MAX6160 MAX6160 ADJ 1/2 MAX5477 1/2 MAX5478 1/2 MAX5479 WA R GND ADJ GND LA 1/2 MAX5477 1/2 MAX5478 1/2 MAX5479 WB R WHERE R = RHL x D / 256 AND D = DECIMAL VALUE OF WIPER CODE LB Figure 13. Adjustable Voltage Reference Pin Configurations Chip Information PROCESS: BiCMOS TOP VIEW + VDD HA WA LA 16 15 14 13 1 SCL 2 SDA 3 A0 N.C. MAX5477 MAX5478 MAX5479 Package Information + HA 1 14 VDD 12 HB WA 2 13 SCL 11 WB LA 3 10 LB 4 9 5 A1 6 A2 7 8 GND WP HB 4 MAX5477 MAX5478 MAX5479 11 A0 WB 5 10 A1 LB 6 9 A2 WP 7 8 GND N.C. THIN QFN (3mm x 3mm) 12 SDA For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 16 TQFN-EP T1633F+3 21-0136 90-0033 14 TSSOP U14+1 21-0066 90-0113 TSSOP (4.4mm x 5mm) ______________________________________________________________________________________ 15 MAX5477/MAX5478/MAX5479 Dual, 256-Tap, Nonvolatile, I2C-Interface, Digital Potentiometers Revision History REVISION NUMBER REVISION DATE 0 8/04 Initial release 4 1/09 Updated Ordering Information for lead-free information. 5 11/11 Released TQFN packages, revised Ordering Information. DESCRIPTION PAGES CHANGED — 1 1–4, 15, 16 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. 16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2011 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.