8-Bit, 100 MSPS+ a TxDAC D/A Converter AD9708 FUNCTIONAL BLOCK DIAGRAM FEATURES Member of Pin-Compatible TxDAC Product Family +5V 125 MSPS Update Rate 0.1mF 8-Bit Resolution Linearity: 1/4 LSB DNL AVDD REFLO COMP1 ACOM Linearity: 1/4 LSB INL +1.20V REF AD9708 Differential Current Outputs 50pF 0.1mF 0.1mF REF IO SINAD 5 MHz Output: 50 dB COMP2 CURRENT SOURCE Power Dissipation: 175 mW 5 V to 45 mW 3 V FS ADJ ARRAY R Power-Down Mode: 20 mW 5 V SET IOUTA +5V DVDD On-Chip 1.20 V Reference SEGMENTED DCOM IOUTB SWITCHES Single +5 V or +3 V Supply Operation CLOCK Packages: 28-Lead SOIC and 28-Lead TSSOP CLOCK LATCHES SLEEP Edge-Triggered Latches Fast Settling: 35 ns Full-Scale Settling to 0.1% DIGITAL DATA INPUTS (DB7DB0) APPLICATIONS Differential current outputs are provided to support single- Communications ended or differential applications. The current outputs may be Signal Reconstruction directly tied to an output resistor to provide two complemen- Instrumentation tary, single-ended voltage outputs. The output voltage compliance PRODUCT DESCRIPTION range is 1.25 V. The AD9708 is the 8-bit resolution member of the TxDAC The AD9708 contains a 1.2 V on-chip reference and reference series of high performance, low power CMOS digital-to-analog control amplifier, which allows the full-scale output current to converters (DACs). The TxDAC family, which consists of pin be simply set by a single resistor. The AD9708 can be driven by compatible 8-, 10-, 12-, and 14-bit DACs, was specifically opti- a variety of external reference voltages. The AD9708s full-scale mized for the transmit signal path of communication systems. All current can be adjusted over a 2 mA to 20 mA range without of the devices share the same interface options, small outline any degradation in dynamic performance. Thus, the AD9708 package and pinout, thus providing an upward or downward may operate at reduced power levels or be adjusted over a 20 dB component selection path based on performance, resolution and range to provide additional gain ranging capabilities. cost. The AD9708 offers exceptional ac and dc performance The AD9708 is available in 28-lead SOIC and 28-lead TSSOP while supporting update rates up to 125 MSPS. packages. It is specified for operation over the industrial tem- The AD9708s flexible single-supply operating range of +2.7 V perature range. to +5.5 V and low power dissipation are well suited for portable and low power applications. Its power dissipation can be PRODUCT HIGHLIGHTS further reduced to 45 mW, without a significant degradation in 1. The AD9708 is a member of the TxDAC product family, which performance, by lowering the full-scale current output. In addi- provides an upward or downward component selection path tion, a power-down mode reduces the standby power dissipa- based on resolution (8 to 14 bits), performance and cost. tion to approximately 20 mW. 2. Manufactured on a CMOS process, the AD9708 uses a pro- The AD9708 is manufactured on an advanced CMOS process. prietary switching technique that enhances dynamic perfor- A segmented current source architecture is combined with a mance well beyond 8- and 10-bit video DACs. proprietary switching technique to reduce spurious components 3. On-chip, edge-triggered input CMOS latches readily interface and enhance dynamic performance. Edge-triggered input latches to +3 V and +5 V CMOS logic families. The AD9708 can and a temperature compensated bandgap reference have been inte- support update rates up to 125 MSPS. grated to provide a complete monolithic DAC solution. Flexible 4. A flexible single-supply operating range of +2.7 V to +5.5 V supply options support +3 V and +5 V CMOS logic families. and a wide full-scale current adjustment span of 2 mA to The AD9708 is a current-output DAC with a nominal full-scale 20 mA allows the AD9708 to operate at reduced power levels output current of 20 mA and > 100 kW output impedance. (i.e., 45 mW) without any degradation in dynamic performance. TxDAC is a registered trademark of Analog Devices, Inc. 5. A temperature compensated, 1.20 V bandgap reference is included on-chip providing a complete DAC solution. An external reference may be used. REV. B 6. The current output(s) of the AD9708 can easily be config- ured for various single-ended or differential applications. Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. use, nor for any infringements of patents or other rights of third parties Tel: 781/329-4700 World Wide Web Site: AD9708SPECIFICATIONS DC SPECIFICATIONS (T to T , AVDD = +5 V, DVDD = +5 V, I = 20 mA, unless otherwise noted) MIN MAX OUTFS Parameter Min Typ Max Units RESOLUTION 8 Bits MONOTONICITY GUARANTEED OVER SPECIFIED TEMPERATURE RANGE 1 DC ACCURACY Integral Linearity Error (INL) 1/2 1/4 +1/2 LSB Differential Nonlinearity (DNL) 1/2 1/4 +1/2 LSB ANALOG OUTPUT Offset Error 0.025 +0.025 % of FSR Gain Error (Without Internal Reference) 10 2 +10 % of FSR Gain Error (With Internal Reference) 10 1 +10 % of FSR 2 Full-Scale Output Current 2.0 20.0 mA Output Compliance Range 1.0 1.25 V Output Resistance 100 kW Output Capacitance 5 pF REFERENCE OUTPUT Reference Voltage 1.08 1.20 1.32 V 3 Reference Output Current 100 nA REFERENCE INPUT Input Compliance Range 0.1 1.25 V Reference Input Resistance 1 MW 4 Small Signal Bandwidth (w/o C ) 1.4 MHz COMP1 TEMPERATURE COEFFICIENTS Offset Drift 0 ppm of FSR/ C Gain Drift (Without Internal Reference) 50 ppm of FSR/ C (With Internal Reference) 100 ppm of FSR/ C Gain Drift Reference Voltage Drift 50 ppm/ C POWER SUPPLY Supply Voltages 5 2.7 5.0 5.5 V AVDD DVDD 2.7 5.0 5.5 V )2530mA Analog Supply Current (I AVDD 6 ) 36 mA Digital Supply Current (I DVDD ) 8.5 mA Supply Current Sleep Mode (I AVDD 6 (5 V, I = 20 mA) 140 175 mW Power Dissipation OUTFS 7 (5 V, I = 20 mA) 190 mW Power Dissipation OUTFS 7 (3 V, I = 2 mA) 45 mW Power Dissipation OUTFS Power Supply Rejection RatioAVDD 0.4 +0.4 % of FSR/V Power Supply Rejection RatioDVDD 0.025 +0.025 % of FSR/V OPERATING RANGE 40 +85 C NOTES 1 Measured at IOUTA, driving a virtual ground. 2 Nominal full-scale current, I , is 32 the I current. OUTFS REF 3 Use an external buffer amplifier to drive any external load. 4 Reference bandwidth is a function of external cap at COMP1 pin. 5 For operation below 3 V, it is recommended that the output current be reduced to 12 mA or less to maintain optimum performance. 6 Measured at f = 50 MSPS and f = 1.0 MHz. CLOCK OUT 7 Measured as unbuffered voltage output into 50 W R at IOUTA and IOUTB, f = 100 MSPS and f = 40 MHz. LOAD CLOCK OUT Specifications subject to change without notice. 2 REV. B