THS1403IPFB




 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005

              FEATURES D 14-Bit Resolution D 1, 3, and 8 MSPS Speed Grades Available D Differential Nonlinearity (DNL) ±0.6 LSB Typ D Integral Nonlinearity (INL) ±1.5 LSB Typ D Internal Reference D Differential Inputs D Programmable Gain Amplifier D µP-Compatible Parallel Interface D Timing Compatible With TMS320C6000 DSP D 3.3-V Single Supply D Power-Down Mode D Monolithic CMOS Design DESCRIPTION The THS1401, THS1403, and THS1408 are 14-bit, 1/3/8 MSPS, single supply analog-to-digital converters (ADCs) with an internal reference, differential inputs, programmable input gain, and an on-chip sample-and-hold amplifier. Implemented with a CMOS process, the device has outstanding price/performance and power/speed ratios. The THS1401, THS1403, and THS1408 are designed for use with 3.3-V systems, and with a high-speed µPcompatible parallel interface, making them the first choice for solutions based on high-performance DSPs such as the TI TMS320C6000 series. The THS1401, THS1403, and THS1408 are available in a TQFP-48 package in standard commercial and industrial temperature ranges. The THS1401, THS1403, and THS1408 are also available in a PQFP-48 package in automotive temperature range, and the THS1408 is available in a PQFP-48 package in military temperature range. APPLICATIONS D xDSL Front Ends D Communication D Industrial Control D Instrumentation D Automotive VBG REF+ REF REF− 1.5 V BG IN+ PGA 0..7 dB 14-Bit ADC 14 15 Buffer D[13:0] + OV bit IN− 6 CLK CONTROL LOGIC A[1:0] CS WR OE Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. Copyright  1999−2005, Texas Instruments Incorporated   !"#$%" & '(##) %& "! *(+,'%" -%). #"-('& '"!"#$ " &*)'!'%"& *)# /) )#$& "! )0%& &#($)& &%-%#- 1%##%2. #"-('" *#"')&&3 -")& " )')&&%#,2 ',(-) )&3 "! %,, *%#%$))#&. www.ti.com  *#"-('& '"$*,% "   4 4 %,, *%#%$))#& %#) )&)- (,)&& "/)#1&) ")-.  %,, "/)# *#"-('& *#"-('" *#"')&&3 -")& " )')&&%#,2 ',(-) )&3 "! %,, *%#%$))#&. 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 ABSOLUTE MAXIMUM RATINGS Over operating free-air temperature range unless otherwise noted.(1) Supply voltage, (AVDD to AGND) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4V Supply voltage, (DVDD to DGND) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4V Reference input voltage range, VBG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . − 0.3 V to AVDD + 0.3 V Analog input voltage range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . − 0.3 V to AVDD + 0.3 V Digital input voltage range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . − 0.3 V to DVDD + 0.3 V Operating free-air temperature range, TA: C-suffix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C I-suffix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −40°C to 85°C Q-suffix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −40°C to 125°C M-suffix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −55°C to 125°C Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −65°C to 150°C Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260°C (1) 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 under recommended operating conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. Terminal Functions TERMINAL NAME 2 NO. A[1:0] 40, 41 AGND 7,8, 44, 45, 46 AVDD CLK 2, 43, 47 CML 4 32 CS 37 DGND 9, 15, 25, 33, 34 DVDD D[13:0] 14, 20, 26, 30, 31, 42 11, 12, 13, 16, 17, 18, 19, 21, 22, 23, 24, 27, 28, 29 I/O I DESCRIPTION Address input Analog ground Analog power supply I Clock input Reference midpoint. This pin requires a 0.1-µF capacitor to AGND. I Chip select input. Active low. Digital ground Digital power supply I/O Data inputs/outputs NC 38, 39 No connection; do not use. Reserved. IN+ 48 I Positive differential analog input IN− 1 I Negative differential analog input OE 35 I Output enable. Active low. OV 10 O Out-of-range output REF+ 5 O Positive reference output. This pin requires a 0.1-µF capacitor to AGND. REF− 6 O Negative reference output. This pin requires a 0.1-µF capacitor to AGND. VBG 3 I Reference input. This pin requires a 1-µF capacitor to AGND. WR 36 I Write signal. Active low. 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 NC CS NC A1 A0 DV DD AGND AV DD AGND AGND IN+ AV DD PFB AND PHP PACKAGE (TOP VIEW) 48 47 46 45 44 43 42 41 40 39 38 37 WR IN− 1 36 AVDD VBG 2 35 OE 3 34 DGND DGND CML 4 33 REF+ 5 32 REF− 6 31 AGND 7 30 AGND 8 29 D0 D1 CLK DVDD DVDD 9 28 OV 10 27 D2 D13 11 26 D12 12 25 DVDD DGND DGND D3 D4 D6 D5 D7 DV DD D8 D10 D9 D11 DV DD DGND 13 14 15 16 17 18 19 20 21 22 23 24 NC − No internal connection AVAILABLE OPTIONS PACKAGED DEVICE TA TQFP (PFB) PQFP (Power Pad) (PHP) 0°C to 70°C THS1401CPFB, THS1403CPFB, THS1408CPFB — −40°C to 85°C THS1401IPFB, THS1403IPFB, THS1408IPFB — −40°C to 125°C — THS1401QPHP, THS1403QPHP, THS1408QPHP −55°C to 125°C — THS1408MPHP 3 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 THERMAL CHARACTERISTICS(1) TYP Thermal resistance, junction-to-ambient, ΘJA Thermal resistance, junction-to-case, ΘJC PFB package 85.9 PHP package 28.8 PFB package 19.6 PHP package 0.79 UNIT °C/W °C/W (1) Thermal resistance is modeled data, is not production tested, and is given for informational purposes only. RECOMMENDED OPERATING CONDITIONS MIN NOM MAX Supply voltage, AVDD, DVDD 3 3.3 3.6 High level digital input, VIH 2 3.3 Low level digital input, VIL 0 Clock duty cycle 4 V V 5 THS1401 0.1 1 1 MHz THS1403 0.1 3 3 MHz THS1408 0.1 8 8 MHz C- and I-suffix 40 50 60 Q- and M-suffix 45 50 55 C-suffix Operating free-air temperature V 0.8 15 Load capacitance, CL Clock frequency, fCLK UNIT 0 25 70 I-suffix −40 25 85 Q-suffix −40 25 125 M-suffix −55 25 125 pF % °C 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 ELECTRICAL CHARACTERISTICS Over operating free-air temperature range, AVDD = DVDD = 3.3V, unless otherwise noted. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT 81 90 mA 5 10 mA 270 360 mW Power Supply IDDA IDDD Analog supply current Digital supply current AVDD = 3.6 V DVDD = 3.6 V Power AVDD = DVDD = 3.6 V Power down current µA 20 DC Characteristics Resolution DNL INL 14 Integral nonlinearity ±1 THS1401 ±1.5 ±2.5 THS1403C/I ±1.5 ±2.5 ±2 ±3 ±3 ±5 ±3.5 ±7.5 THS1403Q Best fit THS1408C/I THS1408Q/M Offset error IN+ = IN−, PGA = 0 dB C and I suffix Gain error Bits ±0.6 Differential nonlinearity Q and M suffix PGA = 0 dB LSB LSB 0.3 %FSR 1 %FSR 1.75 %FSR AC Characteristics ENOB Effective number of bits 11.2 THS1401/3/8 THD Total harmonic distortion THS1403/8 THS1408 THS1401/3/8 SNR Signal-to-noise ratio THS1403/8 THS1408 THS1401/3/8 SINAD Signal-to-noise ratio + distortion THS1403/8 THS1408 THS1401/3/8 −81 fi = 4 MHz fi = 100 kHz −77 fi = 1 MHz fi = 4 MHz fi = 100 kHz fi = 1 MHz Spurious-free dynamic range Analog input bandwidth −78 THS1403Q, THS1408Q/M fi = 1 MHz THS1408 fi = 4 MHz Bits dB 72 70 72 dB 71 70 69 fi = 4 MHz fi = 100 kHz THS1403C/I, THS1408C/I SFDR 11.5 fi = 100 kHz fi = 1 MHz 70 dB 70 80 73 80 71 80 dB 80 140 MHz 5 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 ELECTRICAL CHARACTERISTICS (Cont.) Over operating free-air temperature range, AVDD = DVDD = 3.3V, unless otherwise noted. PARAMETER TEST CONDITIONS MIN TYP MAX 1.425 1.5 1.575 UNIT Reference Voltage Bandgap voltage, internal mode V Input impedance 40 kΩ Positive reference voltage, REF+ 2.5 V Negative reference voltage, REF− 0.5 V 2 V Reference difference, ∆REF, REF+ − REF− Accuracy, internal reference 5% Temperature coefficient Voltage coefficient 40 ppm/°C 200 ppm/V Analog Inputs Positive analog input, IN+ 0 Negative analog input, IN− Analog input voltage difference ∆AIN = IN+ − IN−, VREF = REF+ − REF− V 0 AVDD AVDD −VREF VREF V Input impedance 25 PGA range 0 PGA step size kΩ 7 1 dB dB ±0.25 PGA gain error V dB Digital Inputs VIH VIL High-level digital input 2 V Low-level digital input 0.8 Input capacitance 5 ±1 Input current V pF µA Digital Outputs VOH VOL High-level digital output Low-level digital output IOH = 50 µA IOL = 50 µA 2.6 V IOZ Output current, high impedance Clock Timing (CS low) td Clock frequency 1 1 MHz THS1403 3 3 MHz THS1408 0.1† 8 8 MHz Output delay time Latency † This parameter is not production tested for Q- and M-suffix devices. 6 V µA 0.1† 0.1† THS1401 fCLK 0.4 ±10 25 9.5 ns Cycles 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 PARAMETER MEASUREMENT INFORMATION sample timing The THS1401/3/8 core is based on a pipeline architecture with a latency of 9.5 samples. The conversion results appear on the digital output 9.5 clock cycles after the input signal was sampled. S11 S9 S12 S10 Analog Input tw(CLK) tw(CLK) CLK td Data Out C1 C2 C3 Figure 1. Sample Timing The parallel interface of the THS1401/3/8 ADC features 3-state buffers, making it possible to directly connect it to a data bus. The output buffers are enabled by driving the OE input low. Besides the sample results, it is also possible to read back the values of the control register, the PGA register, and the offset register. Which register is read is determined by the address inputs A[1,0]. The ADC results are available at address 0. The timing of the control signals is described in the following sections. 7 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 PARAMETER MEASUREMENT INFORMATION read timing (15-pF load) PARAMETER tsu(OE−ACS) ten Address and chip select setup time tdis th(A) Output disable MIN TYP MAX 4 ns Output enable 15 10 Address hold time th(CS) Chip select hold time NOTE: All timing parameters refer to a 50% level. ns ns 0 ns th(CS) OE ten tdis DATA D[13:0] OV th(A) A[1:0] X ADDRESS Figure 2. Read Timing 8 ns 1 CS tsu(OE−ACS) UNIT X 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 PARAMETER MEASUREMENT INFORMATION write timing (15-pF load) PARAMETER tsu(WE−CS) tsu(DA) Chip select setup time th(DA) th(CS) MIN TYP MAX UNIT 4 ns Data and address setup time 29 ns Data and address hold time 0 ns Chip select hold time 0 ns 15 ns twH(WE) Write pulse duration high NOTE: All timing parameters refer to a 50% level. CS th(CS) WE tsu(WE−CS) D[13:0] tsu(DA) X DATA X th(DA) A X ADDRESS X Figure 3. Write Timing 9 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 TYPICAL CHARACTERISTICS POWER vs FREQUENCY SUPPLY CURRENT vs TIME 284 90 282 80 70 I CC − Supply Current − mA Power − mW 280 278 276 274 272 270 60 50 40 30 20 10 0 268 0.1 1 f − Frequency − MHz 10 0 50 Figure 4 100 150 200 t − Time − ns 250 Figure 5 FAST FOURIER TRANSFORM 0 fs = 1 MSPS, fI = 100 kHz, −1 dB Output − dB −20 −40 −60 −80 −100 −120 −140 0 100 200 300 f − Frequency − kHz Figure 6 10 400 500 300 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 TYPICAL CHARACTERISTICS FAST FOURIER TRANSFORM 0 fs = 3 MSPS, fI = 1 MHz, −1 dB Output − dB −20 −40 −60 −80 −100 −120 −140 0.1 0.4 0.7 1.3 1 f − Frequency − MHz Figure 7 FAST FOURIER TRANSFORM 0 fs = 8 MSPS, fI = 1 MHz, −1 dB Output − dB −20 −40 −60 −80 −100 −120 −140 0.1 0.4 0.7 1 1.3 1.6 1.9 2.2 2.5 2.8 3.1 3.4 3.7 4 f − Frequency − MHz Figure 8 INL − Integral Nonlinearity − LSB INTEGRAL NONLINEARITY 2 fs = 1 MSPS 1.5 1 0.5 0 −0.5 −1 −1.5 −2 0 2048 4096 6144 8192 10240 12288 14336 16384 Samples Figure 9 11 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 TYPICAL CHARACTERISTICS INL − Integral Nonlinearity − LSB INTEGRAL NONLINEARITY 2 fs = 3 MSPS 1.5 1 0.5 0 −0.5 −1 −1.5 −2 0 2048 4096 6144 8192 10240 12288 14336 16384 Samples Figure 10 INL − Integral Nonlinearity − LSB INTEGRAL NONLINEARITY 4 fs = 8 MSPS 3 2 1 0 −1 −2 −3 −4 0 2048 4096 6144 8192 10240 12288 14336 16384 Samples Figure 11 DNL − Differential Nonlinearity − LSB DIFFERENTIAL NONLINEARITY 1 0.8 0.6 fs = 1 MSPS 0.4 0.2 0 −0.2 −0.4 −0.6 −0.8 −1 0 2048 4096 6144 8192 Samples Figure 12 12 10240 12288 14336 16384 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 TYPICAL CHARACTERISTICS DNL − Differential Nonlinearity − LSB DIFFERENTIAL NONLINEARITY 1 0.8 fs = 3 MSPS 0.6 0.4 0.2 0 −0.2 −0.4 −0.6 −0.8 −1 0 2048 4096 6144 8192 10240 12288 14336 16384 Samples Figure 13 DNL − Differential Nonlinearity − LSB DIFFERENTIAL NONLINEARITY 1 0.8 0.6 fs = 8 MSPS 0.4 0.2 0 −0.2 −0.4 −0.6 −0.8 −1 0 2048 4096 6144 8192 10240 12288 14336 16384 Samples Figure 14 13 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 TYPICAL CHARACTERISTICS TOTAL HARMONIC DISTORTION vs FREQUENCY TOTAL HARMONIC DISTORTION vs FREQUENCY −70 −70 fs = 8 MSPS, fI at −1 dB −72 THD − Total Harmonic Distortion − dB THD − Total Harmonic Distortion − dB −72 fs = 3 MSPS, fI at −1 dB −74 −76 −78 −80 −82 −84 −86 −88 −74 −76 −78 −80 −82 −84 −86 −88 −90 10 −90 100 f − Frequency − Hz 1000 1500 10 100 Figure 16 SIGNAL-TO-NOISE RATIO vs FREQUENCY SIGNAL-TO-NOISE RATIO vs FREQUENCY 80 78 SNR − Signal-to-Noise Ratio − dB SNR − Signal-to-Noise Ratio − dB 80 fs = 3 MSPS, fI at −1 dB 76 74 72 70 68 66 64 62 60 10 fs = 8 MSPS, fI at −1 dB 76 74 72 70 68 66 64 62 100 f − Frequency − Hz Figure 17 14 4000 f − Frequency − Hz Figure 15 78 1000 1000 1500 60 10 100 f − Frequency − Hz Figure 18 1000 4000 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 PRINCIPLES OF OPERATION registers The device contains several registers. The A register is selected by the values of bits A1 and A0: A1 A0 Register 0 0 Conversion result 0 1 PGA 1 0 Offset 1 1 Control Tables 1 and 2 describe how to read the conversion results and how to configure the data converter. The default values (were applicable) show the state after a power-on reset. Table 1. Conversion Result Register, Address 0, Read BIT D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Function MSB ... … … … … … … … … … … … LSB The output can be configured for 2s complement or straight binary format (see D11/control register). The output code is given by: 2s complement: −8192 at ∆IN = −∆REF 0 at ∆IN = 0 8191 ∆IN = +∆REF − 1 LSB Straight binary: 0 at ∆IN = −∆REF 8192 at ∆IN = 0 16383 at ∆IN = + ∆REF − 1 LSB 1 LSB + 2DREF 16384 Table 2. PGA Gain Register, Address 1, Read/Write BIT D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Function X X X X X X X X X X X G2 G1 G0 Default 0 0 0 0 0 0 0 0 0 0 0 0 0 0 The PGA gain is determined by writing to G2−0. Gain (dB) = 1dB × G2−0. max = 7dB. The range of G2−0 is 0 to 7. Table 3. Offset Register, Address 2, Read/Write BIT D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Function X X X X X X MSB … … … … … … LSB Default 0 0 0 0 0 0 0 0 0 0 0 0 0 0 The offset correction range is from –128 to 127 LSB. This value is added to the conversion results from the ADC. 15 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 PRINCIPLES OF OPERATION Table 4. Control Register, Address 3, Read BIT D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Function PWD REF FOR TM2 TM1 TM0 OFF RES RES RES RES RES RES RES Table 5. Control Register, Address 3, Write BIT D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Function PWD REF FOR TM2 TM1 TM0 OFF RES RES RES RES RES RES RES Default 0 0 0 0 0 0 0 0 0 0 0 0 0 0 PWD: Power down 0 = normal operation 1 = power down REF: Reference select 0 = internal reference 1 = external reference FOR: Output format 0 = straight binary 1 = 2s complement TM2−0: Test mode 000 = normal operation 001 = both inputs = REF− 010 = IN+ at VCM (Voltage at CML pin), IN− at REF− 011 = IN+ at REF+, IN− at REF− 100 = normal operation 101 = both inputs = REF+ 110 = IN+ at REF−, IN− at VCM (Voltage at CML pin) 111 = IN+ at REF−, IN− at REF+ OF: Offset correction 0 = enable 1 = disable RES Reserved Must be set to 0. APPLICATION INFORMATION driving the analog input The THS1401/3/8 ADCs have a fully differential input. A differential input is advantageous with respect to SNR, SFDR, and THD performance because the signal peak-to-peak level is 50% of a comparable single-ended input. There are three basic input configurations: D Fully differential D Transformer coupled single-ended to differential D Single-ended fully differential configuration In this configuration, the ADC converts the difference (∆IN) of the two input signals on IN+ and IN−. 22 Ω 100 pF IN+ THS1401/3/8 22 Ω IN− 100 pF Figure 19. Differential Input 16 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 The resistors and capacitors on the inputs decouple the driving source output from the ADC input and also serve as first order low pass filters to attenuate out of band noise. The input range on both inputs is 0 V to AVDD. The full-scale value is determined by the voltage reference. The positive full-scale output is reached, if ∆IN equals ∆REF, the negative full-scale output is reached, if ∆IN equals −∆REF. ∆IN [V] OUTPUT −∆REF − full scale 0 0 ∆REF + full scale APPLICATION INFORMATION transformer coupled single-ended to differential configuration If the application requires the best SNR, SFDR, and THD performance, the input should be transformer coupled. The signal amplitude on both inputs of the ADC is one half as high as in a single-ended configuration thus increasing the ADC ac performance. 22 Ω IN+ 100 pF R THS1401/3/8 22 Ω IN− 100 pF + CML 1 µF 0.1 µF Figure 20. Transformer Coupled The following table shows the input voltages for negative full-scale output, zero output, and positive full-scale output: IN [VPEAK] −∆REF OUTPUT [PEAK] − full scale† 0 0 ∆REF + full scale† † n = 1 (winding ratio) The resistor R of the transformer coupled input configuration must be set to match the signal source impedance R = n2 Rs, where Rs is the source impedance and n is the transformer winding ratio. APPLICATION INFORMATION single-ended configuration In this configuration, the input signal is level shifted by ∆REF/2. 17 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 10 kΩ + 10 kΩ 10 kΩ 10 kΩ IN+ 100 pF REF+ THS1401/3/8 22 Ω − IN− 100 pF + 10 kΩ REF− 10 kΩ Figure 21. Single-Ended With Level Shift The following table shows the input voltages for negative full-scale output, zero output, and positive full-scale output: ∆IN+ [V] OUTPUT −∆REF − full scale 0 0 ∆REF + full scale Note that the resistors of the op-amp and the op-amp all introduce gain and offset errors. Those errors can be trimmed by varying the values of the resistors. Because of the added offset, the op-amp does not necessarily operate in the best region of its transfer curve (best linearity around zero) and therefore may introduce unacceptable distortion. For ac signals, an alternative is described in the following section. APPLICATION INFORMATION AC-coupled single-ended configuration If the application does not require the signal bandwidth to include dc, the level shift shown in Figure 21 is not necessary. 10 kΩ 10 kΩ 10 kΩ 10 kΩ IN+ 100 pF REF+ THS1401/3/8 − + 10 nF IN− 22 Ω 100 pF REF− 10 kΩ 10 kΩ Figure 22. Single-Ended With Level Shift Because the signal swing on the op-amp is centered around ground, it is more likely that the signal stays within the linear region of the op-amp transfer function, thus increasing the overall ac performance. IN [VPEAK] OUTPUT [PEAK] −∆REF − full scale 0 0 ∆REF + full scale Compared to the transformer-coupled configuration, the swing on IN− is twice as big, which can decrease the ac performance (SNR, SFD, and THD). 18 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 APPLICATION INFORMATION internal/external reference operation The THS1401/3/8 ADC can either be operated using the built-in band gap reference or using an external precision reference in case very high dc accuracy is needed. The REF+ and REF+ outputs are given by: ǒ Ǔ REF )+ VBG 1 ) 2 and REF– 3 If the built-in reference is used, VBG equals 1.5 V which results in REF+ = 2.5 V, REF− = 0.5 V and ∆REF = 2 V. The internal reference can be disabled by writing 1 to D12 (REF) in the control register (address 3). The band gap reference is then disconnected and can be substituted by a voltage on the VBG pin. programmable gain amplifier The on-chip programmable gain amplifier (PGA) has eight gain settings. The gain can be changed by writing to the PGA gain register (address 1). The range is 0 to 7dB in steps of one dB. out of range indication The OV output of the ADC indicates an out of range condition. Every time the difference on the analog inputs exceeds the differential reference, this signal is asserted. This signal is updated the same way as the digital data outputs and therefore subject to the same pipeline delay. conditioning circuitry. If the offset compensation is enabled (D7 (OFF) in the control register), the value in the offset register (address 2) is automatically added to the output of the ADC. In order to set the correct value of the offset compensation register, the ADC result when the input signal is 0 must be read by the host processor and written to the offset register (address 2). test modes The ADC core operation can be tested by selecting one of the available test modes (see control register description). The test modes apply various voltages to the differential input depending on the setting in the control register. digital I/O The digital inputs and outputs of the THS1401/3/8 ADC are 3-V CMOS compatible. In order to avoid current feed back errors, the capacitive load on the digital outputs should be as low as possible (50 pF max). Series resistors (100 Ω) on the digital outputs can improve the performance by limiting the current during output transitions. The parallel interface of the THS1401/3/8 ADC features 3-state buffers, making it possible to directly connect it to a data bus. The output buffers are enabled by driving the OE input low. Refer to the read and write timing diagrams in the parameter measurement information section for information on read and write access. offset compensation With the offset register it is possible to automatically compensate system offset errors, including errors caused by additional signal 19 


 
 www.ti.com SLAS248D − DECEMBER 1999 − REVISED SEPTEMBER 2005 Revision History DATE 9/05 REV D PAGE SECTION 1 — Updated page 1 format and layout. 1 — Moved funtional block diagram from page 2. 2 — Moved Terminal Function table from page 3. 2 — Moved Absolute Maximum table from page 4. 3 — Moved package pinout from page 1. 3 — Moved Ordering Options table from page 2. 15 16 DESCRIPTION Principles of Operation Table 1. In section 2s complement: 8191 DIN = − DREF − 1 LSB changed to 8191 DIN = +DREF − 1 LSB. In section Straight Binary: 16383 at DIN = − DREF − 1 LSB should be changed to 16383 DIN = +DREF − 1 LSB Principles of Operation Table 5. In section TM2−0: Test Mode: 010 = IN+ at VREF /2, IN− at REF−, changed to, 010 = IN+ at VCM (Voltage at CML pin), IN− at REF−. Same section: 110 = IN+ at REF−, IN− at VREF /2, changed to, 110 = IN+ at REF−, IN− at VCM (Voltage at CML pin) NOTE: Page numbers for previous revisions may differ from page numbers in the current version. 20 PACKAGE OPTION ADDENDUM www.ti.com 10-Dec-2020 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) (4/5) (6) 5962-0051101NXD ACTIVE HTQFP PHP 48 250 RoHS & Green NIPDAU Level-3-260C-168 HR -55 to 125 0051101 NXD THS1401IPFB ACTIVE TQFP PFB 48 250 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 TJ1401 THS1403IPFB ACTIVE TQFP PFB 48 250 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 TJ1403 THS1408IPFB ACTIVE TQFP PFB 48 250 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 TJ1408 (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of