HI5810KIB

HI5810 August 1997 CMOS 10 Microsecond, 12-Bit, Sampling A/D Converter with Internal Track and Hold Description The HI5810 is a fast, low power, 12-bit, successiveapproximation, analog-to-digital converter. It can operate from a single 3V to 6V supply and typically draws just 1.9mA when operating at 5V. The HI5810 features a built-in track and hold. The conversion time is as low as 10µs with a 5V supply. The twelve data outputs feature full high speed CMOS threestate bus driver capability, and are latched and held through a full conversion cycle. The output is user selectable: [i.e., 12-bit, 8-bit (MSBs), and/or 4-bit (LSBs)]. A data ready flag, and conversion-start input complete the digital interface. An internal clock is provided and is available as an output. The clock may also be over-driven by an external source. Features • Conversion Time . . . . . . . . . . . . . . . . . . . . . . . . . . . 10µs • Throughput Rate . . . . . . . . . . . . . . . . . . . . . . .100 KSPS • Built-In Track and Hold • Single Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . +5V • Maximum Power Consumption. . . . . . . . . . . . . . .40mW • Internal or External Clock • 1MHz Input Bandwidth . . . . . . . . . . . . . . . . . . . . . -3dB Applications • Remote Low Power Data Acquisition Systems • Digital Audio • DSP Modems • General Purpose DSP Front End • µP Controlled Measurement Systems • Process Controls • Industrial Controls Ordering Information PART NUMBER HI5810JIP HI5810KIP HI5810JIB HI5810KIB HI5810JIJ HI5810KIJ INL (LSB) (MAX OVER TEMP.) ±2.5 ±2.0 ±2.5 ±2.0 ±2.5 ±2.0 TEMP. RANGE (oC) PKG. NO. E24.3 E24.3 M24.3 M24.3 PACKAGE -40 to 85 24 Ld PDIP -40 to 85 24 Ld PDIP -40 to 85 24 Ld SOIC -40 to 85 24 Ld SOIC -40 to 85 24 Ld CERDIP F24.3 -40 to 85 24 Ld CERDIP F24.3 Pinout HI5810 (PDIP, CERDIP, SOIC) TOP VIEW DRDY (LSB) D0 D1 D2 D3 D4 D5 D6 D7 1 2 3 4 5 6 7 8 9 24 VDD 23 OEL 22 CLK 21 STRT 20 VREF 19 VREF+ 18 VIN 17 VAA+ 16 VAA 15 OEM 14 D11 (MSB) 13 D10 D8 10 D9 11 VSS 12 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 321-724-7143 | Copyright © Intersil Corporation 1999 File Number 3633.1 6-1777 HI5810 Functional Block Diagram STRT VDD VSS VIN CONTROL AND TIMING 32C VREF+ OEM 16C D11 (MSB) 50Ω SUBSTRATE 8C D10 4C 2C VAA+ C VAA64C 63 32C D7 16C 8C 4C 2C C D3 C D2 D1 VREF D0 (LSB) OEL 12-BIT SUCCESSIVE APPROXIMATION REGISTER 12-BIT EDGE TRIGGERED “D” LATCHED D8 D9 CLOCK CLK DRDY TO INTERNAL LOGIC D6 D5 D4 P1 6-1778 HI5810 Absolute Maximum Ratings Supply Voltage VDD to VSS . . . . . . . . . . . . . . . . . . . . (VSS -0.5V) < VDD < +6.5V VAA+ to VAA-. . . . . . . . . . . . . . . . . . . . (VSS -0.5V) to (VSS +6.5V) VAA+ to VDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±0.3V Analog and Reference Inputs VIN, VREF+, VREF - . . . . . . . . . (VSS -0.3V) < VINA < (VDD +0.3V) Digital I/O Pins . . . . . . . . . . . . . . (VSS -0.3V) < VI/O < (VDD +0.3V) Thermal Information Thermal Resistance (Typical, Note 1) θJA (oC/W) θJC (oC/W) CERDIP Package . . . . . . . . . . . . . . . . 60 12 PDIP Package . . . . . . . . . . . . . . . . . . . 80 N/A SOIC Package . . . . . . . . . . . . . . . . . . . 75 N/A Maximum Junction Temperature Plastic Packages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150oC Hermetic Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175oC Maximum Storage Temperature Range . . . . . . . . . .-65oC to 150oC Maximum Lead Temperature (Soldering, 10s) . . . . . . . . . . . . 300oC (SOIC - Lead Tips Only) Operating Conditions Temperature Range PDIP, SOIC, and CERDIP Packages . . . . . . . . . . . -40oC to 85oC CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. NOTE: 1. θJA is measured with the component mounted on an evaluation PC board in free air. Electrical Specifications VDD = VAA+ = 5V, VREF+ = +4.608V, VSS = VAA- = VREF - = GND, CLK = External 1.5MHz, Unless Otherwise Specified 25oC -40oC TO 85oC MAX MIN MAX UNITS PARAMETER ACCURACY Resolution Integral Linearity Error, INL (End Point) Differential Linearity Error, DNL J K J K Gain Error, FSE (Adjustable to Zero) Offset Error, VOS (Adjustable to Zero) DYNAMIC CHARACTERISTICS Signal to Noise Ratio, SINAD RMS Signal RMS Noise + Distortion Signal to Noise Ratio, SNR RMS Signal RMS Noise Total Harmonic Distortion, THD J K J K J K Spurious Free Dynamic Range, SFDR J K ANALOG INPUT Input Current, Dynamic J K J K TEST CONDITIONS MIN TYP 12 - - ±2.5 ±2.0 ±2.0 ±2.0 ±3.5 ±2.5 ±2.5 ±1.5 12 - ±2.5 ±2.0 ±2.0 ±2.0 ±3.5 ±2.5 ±2.5 ±1.5 Bits LSB LSB LSB LSB LSB LSB LSB LSB fS = Internal Clock, fIN = 1kHz fS = 1.5MHz, fIN = 1kHz fS = Internal Clock, fIN = 1kHz fS = 1.5MHz, fIN = 1kHz fS = Internal Clock, fIN = 1kHz fS = 1.5MHz, fIN = 1kHz fS = Internal Clock, fIN = 1kHz fS = 1.5MHz, fIN = 1kHz fS = Internal Clock, fIN = 1kHz fS = 1.5MHz, fIN = 1kHz fS = Internal Clock, fIN = 1kHz fS = 1.5MHz, fIN = 1kHz fS = Internal Clock, fIN = 1kHz fS = 1.5MHz, fIN = 1kHz fS = Internal Clock, fIN = 1kHz fS = 1.5MHz, fIN = 1kHz - 68.8 62.1 71.0 63.6 70.5 63.2 71.5 65.0 -73.9 -68.4 -80.3 69.7 75.4 69.2 80.9 70.7 - - - dB dB dB dB dB dB dB dB dBc dBc dBc dBc dB dB dB dB At VIN = VREF+, 0V - ±125 ±150 - ±150 µA 6-1779 HI5810 Electrical Specifications VDD = VAA+ = 5V, VREF+ = +4.608V, VSS = VAA- = VREF - = GND, CLK = External 1.5MHz, Unless Otherwise Specified (Continued) 25oC PARAMETER Input Current, Static Input Bandwidth -3dB Reference Input Current Input Series Resistance, RS Input Capacitance, CSAMPLE Input Capacitance, CHOLD DIGITAL INPUTS OEL, OEM, STRT High-Level Input Voltage, VIH Low-Level Input Voltage, VIL Input Leakage Current, IIL Input Capacitance, CIN DIGITAL OUTPUTS High-Level Output Voltage, VOH Low-Level Output Voltage, VOL Three-State Leakage, IOZ Output Capacitance, COUT CLOCK High-Level Output Voltage, VOH Low-Level Output Voltage, VOL Input Current TIMING Conversion Time (tCONV + tACQ) (Includes Acquisition Time) Clock Frequency Internal Clock, (CLK = Open) External CLK (Note 2) Clock Pulse Width, tLOW, tHIGH Aperture Delay, tDAPR Clock to Data Ready Delay, tD1DRDY Clock to Data Ready Delay, tD2DRDY Start Removal Time, tRSTRT Start Setup Time, tSUSTRT Start Pulse Width, tWSTRT Start to Data Ready Delay, tD3 DRDY Clock Delay from Start, tDSTRT Output Enable Delay, tEN Output Disabled Delay, tDIS POWER SUPPLY CHARACTERISTICS Supply Current, IDD + IAA NOTE: 2. Parameter guaranteed by design or characterization, not production tested. 2.6 8 8.5 mA External CLK (Note 2) (Note 2) (Note 2) (Note 2) (Note 2) (Note 2) (Note 2) (Note 2) (Note 2) (Note 2) (Note 2) 10 200 0.05 100 75 85 10 300 35 105 100 30 60 4 65 60 20 80 400 2.0 50 150 160 105 30 95 10 150 100 75 100 15 500 70 180 195 120 50 120 µs kHz MHz ns ns ns ns ns ns ns ns ns ns ns ISOURCE = -100µA (Note 2) ISINK = 100µA (Note 2) CLK Only, VIN = 0V, 5V 4 1 ±5 4 1 ±5 V V mA ISOURCE = -400µA ISINK = 1.6mA Except DRDY, VOUT = 0V, 5V Except DRDY 4.6 20 0.4 ±10 4.6 0.4 ±10 V V µA pF Except CLK, VIN = 0V, 5V 2.4 10 0.8 ±10 2.4 0.8 ±10 V V µA pF In Series with Input CSAMPLE During Sample State During Hold State TEST CONDITIONS Conversion Stopped MIN TYP ±0.6 1 160 420 380 20 MAX ±10 - -40oC TO 85oC MIN MAX ±10 UNITS µA MHz µA Ω pF pF 6-1780 HI5810 Timing Diagrams 1 CLK (EXTERNAL OR INTERNAL) tD1DRDY STRT tD2DRDY DRDY tLOW tHIGH 2 3 4 5 - 14 15 1 2 3 D0 - D11 DATA N - 1 DATA N VIN OEL = OEM = VSS TRACK N HOLD N TRACK N + 1 FIGURE 1. CONTINUOUS CONVERSION MODE 15 CLK (EXTERNAL) 1 2 2 2 3 4 5 tRSTRT tSUSTRT tWSTRT STRT tD3DRDY DRDY HOLD VIN TRACK HOLD FIGURE 2. SINGLE SHOT MODE EXTERNAL CLOCK 6-1781 HI5810 Timing Diagrams CLK (INTERNAL) 2 tRSTRT tDSTRT tWSTRT STRT DON’T CARE tD3DRDY (Continued) 15 1 3 4 5 DRDY HOLD VIN TRACK HOLD FIGURE 3. SINGLE SHOT MODE INTERNAL CLOCK OEL OR OEM tDIS 90% 50% TO OUTPUT PIN 50% 10% 1.6mA tEN D0 - D3 OR D4 - D11 HIGH IMPEDANCE TO HIGH HIGH IMPEDANCE TO LOW 1.6mA +2.1V 50pF +2.1V 50pF -1.6mA -400µA FIGURE 4. OUTPUT ENABLE/DISABLE TIMING DIAGRAM FIGURE 5. TIMING LOAD CIRCUIT Typical Performance Curves 2.0 1.9 1.8 VOS ERROR (LSBs) INL ERROR (LSBs) 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 -50 VDD = VAA+ = 5V, VREF+ = 4.608V, CLK = 1.5MHz 1.00 0.95 0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.55 0.50 0.45 0.40 0.35 0.30 -50 VDD = VAA+ = 5V, VREF+ = 4.608V, CLK = 1.5MHz -40 -30 -20 -10 0 10 20 30 40 50 TEMPERATURE (oC) 60 70 80 90 -40 -30 -20 -10 0 10 20 30 40 50 TEMPERATURE (oC) 60 70 80 90 FIGURE 6. NL vs TEMPERATUREI FIGURE 7. OFFSET ERROR vs TEMPERATURE 6-1782 HI5810 Typical Performance Curves (Continued) -1.0 -1.1 -1.2 -1.3 -1.4 -1.5 FSE (LSBs) -1.6 -1.7 -1.8 -1.9 -2.0 -2.1 -2.2 -2.3 -2.4 -2.5 -50 VDD = VAA+ = 5V, VREF+ = 4.608V, CLK = 1.5MHz 1.75 1.70 VDD = VAA+ = 5V, VREF+ = 4.608V, CLK = 1.5MHz 1.65 1.60 1.55 1.50 1.45 1.40 1.35 1.30 1.25 1.20 1.15 1.10 1.05 1.00 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 TEMPERATURE (oC) DNL ERROR (LSBs) -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 TEMPERATURE (oC) FIGURE 8. DNL vs TEMPERATURE FIGURE 9. FULL SCALE ERROR vs TEMPERATURE 6.5 6.0 5.5 SUPPLY CURRENT (mA) 5.0 AMPLITUDE (dB) 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 -50 INPUT FREQUENCY = 1kHz SAMPLING RATE = 100kHz SNR = 64.92dB SINAD = 63.82dB EFFECTIVE BITS = 10.30 THD = -69.44dBc PEAK NOISE = -70.1dB SFDR = 70.1dB -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 TEMPERATURE (oC) FREQUENCY FIGURE 10. SUPPLY CURRENT vs TEMPERATURE FIGURE 11. FFT SPECTRUM 500 INTERNAL CLOCK FREQUENCY (kHz) 450 400 350 300 250 200 150 -60 VDD = VAA+ = 5V, VREF+ = 4.608V -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (oC) FIGURE 12. INTERNAL CLOCK FREQUENCY vs TEMPERATURE 6-1783 HI5810 TABLE 1. PIN DESCRIPTIONS PIN NO. 1 NAME DESCRIPTION DRDY Output flag signifying new data is available. Goes high at end of clock period 15. Goes low when new conversion is started. D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 VSS D10 D11 OEM Bit-0 (Least Significant Bit, LSB). Bit 1. Bit 2. Bit 3. Bit 4. Bit 5. Bit 6. Bit 7. Bit 8. Bit 9. Digital Ground, (0V). Bit 10. During the first three clock periods of a conversion cycle, the switchable end of every capacitor is connected to the input and the comparator is being auto balanced at the capacitor common node. During the fourth period, all capacitors are disconnected from the input; the one representing the MSB (D11) is connected to the VREF+ terminal; and the remaining capacitors to VREF -. The capacitor common node, after the charges balance out, will indicate whether the input was above 1/2 of (VREF+ - VREF -). At the end of the fourth period, the comparator output is stored and the MSB capacitor is either left connected to VREF+ (if the comparator was high) or returned to VREF -. This allows the next comparison to be at either 3/4 or 1/4 of (VREF+ - VREF -). At the end of periods 5 through 14, capacitors representing D10 through D1 are tested, the result stored, and each capacitor either left at VREF+ or at VREF -. At the end of the 15th period, when the LSB (D0) capacitor is tested, (D0) and all the previous results are shifted to the output registers and drivers. The capacitors are reconnected to the input, the comparator returns to the balance state, and the data ready output goes active. The conversion cycle is now complete. Analog Input 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Bit 11 (Most Significant Bit, MSB) Three-State Enable for D4-D11. Active low input. Analog Ground, (0V). Analog Positive Supply. (+5V) (See text.) Analog Input. 16 17 18 19 VAAVAA+ VIN The analog input pin is a predominately capacitive load that changes between the track and hold periods of the conversion cycle. During hold, clock period 4 through 15, the input loading is leakage and stray capacitance, typically less than 5µA and 20pF. At the start of input tracking, clock period 1, some charge is dumped back to the input pin. The input source must have low enough impedance to dissipate the current spike by the end of the tracking period as shown in Figure 13. The amount of charge is dependent on supply and input voltages. The average current is also proportional to clock frequency. VREF+ Reference Voltage Positive Input, sets 4095 code end of input range. VREF- Reference Voltage Negative Input, sets 0 code end of input range. STRT Start Conversion Input active low, recognized after end of clock period 15. 20 21 20mA 22 CLK CLK Input or Output. Conversion functions are synchronized to positive going edge (see text). Three-State Enable for D0 D3. Active low input. Digital Positive Supply (+5V). IIN 10mA 0mA 23 24 OEL VDD Theory of Operation The HI5810 is a CMOS 12-bit, Analog-to-Digital Converter that uses capacitor charge balancing to successively approximate the analog input. A binarily weighted capacitor network forms the A/D heart of the device. See the block diagram for the HI5810. The capacitor network has a common node which is connected to a comparator. The second terminal of each capacitor is individually switchable to the input, VREF+ or VREF -. 5V CLK 0V 5V DRDY 0V 200ns/DIV. CONDITIONS: VDD = VAA+ = 5.0V, VREF+ = 4.608V, VIN = 4.608V, CLK = 750kHz, TA = 25oC FIGURE 13. TYPICAL ANALOG INPUT CURRENT 6-1784 HI5810 As long as these current spikes settle completely by end of the signal acquisition period, converter accuracy will be preserved. The analog input is tracked for 3 clock cycles. With an external clock of 1.5MHz the track period is 2µs. A simplified analog input model is presented in Figure 14. During tracking, the A/D input (VIN) typically appears as a 380pF capacitor being charged through a 420Ω internal switch resistance. The time constant is 160ns. To charge this capacitor from an external “zero Ω” source to 0.5 LSB (1/8192), the charging time must be at least 9 time constants or 1.4µs. The maximum source impedance (RSOURCE Max) for a 2µs acquisition time settling to within 0.5 LSB is 164Ω . If the clock frequency was slower, or the converter was not restarted immediately (causing a longer sample time), a higher source impedance could be tolerated. VIN RSW ≈ 420Ω CSAMPLE ≈ 380pF RSOURCE The HI5810 is specified with a 4.608V reference, however, it will operate with a reference down to 3V having a slight degradation in performance. Full Scale and Offset Adjustment In many applications the accuracy of the HI5810 would be sufficient without any adjustments. In applications where accuracy is of utmost importance full scale and offset errors may be adjusted to zero. The VREF+ and VREF - pins reference the two ends of the analog input range and may be used for offset and full scale adjustments. In a typical system the VREF - might be returned to a clean ground, and the offset adjustment done on an input amplifier. VREF+ would then be adjusted to null out the full scale error. When this is not possible, the VREF - input can be adjusted to null the offset error, however, VREF - must be well decoupled. Full scale and offset error can also be adjusted to zero in the signal conditioning amplifier driving the analog input (VIN). Control Signal - RSW RSOURCE (MAX) = CSAMPLE ln [2-(N + 1)] FIGURE 14. ANALOG INPUT MODEL IN TRACK MODE -tACQ The HI5810 may be synchronized from an external source by using the STRT (Start Conversion) input to initiate conversion, or if STRT is tied low, may be allowed to free run. Each conversion cycle takes 15 clock periods. The input is tracked from clock period 1 through period 3, then disconnected as the successive approximation takes place. After the start of the next period 1 (specified by tD data), the output is updated. The DRDY (Data Ready) status output goes high (specified by tD1DRDY) after the start of clock period 1, and returns low (specified by tD2DRDY) after the start of clock period 2. The 12 data bits are available in parallel on three-state bus driver outputs. When low, the OEM input enables the most significant byte (D4 through D11) while the OEL input enables the four least significant bits (D0 - D3). tEN and tDIS specify the output enable and disable times. If the output data is to be latched externally, either the trailing edge of data ready or the next falling edge of the clock after data ready goes high can be used. When STRT input is used to initiate conversions, operation is slightly different depending on whether an internal or external clock is used. Figure 3 illustrates operation with an internal clock. If the STRT signal is removed (at least tRSTRT) before clock period 1, and is not reapplied during that period, the clock will shut off after entering period 2. The input will continue to track and the DRDY output will remain high during this time. A low signal applied to STRT (at least tWSTRT wide) can now initiate a new conversion. The STRT signal (after a delay of (tDSTRT)) causes the clock to restart. Depending on how long the clock was shut off, the low portion of clock period 2 may be longer than during the remaining cycles. Reference Input The reference input VREF+ should be driven from a low impedance source and be well decoupled. As shown in Figure 15, current spikes are generated on the reference pin during each bit test of the successive approximation part of the conversion cycle as the charge balancing capacitors are switched between VREF - and VREF+ (clock periods 5 - 14). These current spikes must settle completely during each bit test of the conversion to not degrade the accuracy of the converter. Therefore VREF+ and VREF should be well bypassed. Reference input VREF - is normally connected directly to the analog ground plane. If VREF- is biased for nulling the converters offset it must be stable during the conversion cycle. 20mA IREF+ 10mA 0mA CLK 5V 0V 5V 0V 2µs/DIV. DRDY CONDITIONS: VDD = VAA+ = 5.0V, VREF+ = 4.608V, VIN = 2.3V, CLK = 750kHz, TA = 25oC FIGURE 15. TYPICAL REFERENCE INPUT CURRENT 6-1785 HI5810 The input will continue to track until the end of period 3, the same as when free running. Figure 2 illustrates the same operation as above but with an external clock. If STRT is removed (at least tRSTRT) before clock period 2, a low signal applied to STRT will drop the DRDY flag as before, and with the first positive going clock edge that meets the (tSUSTRT) setup time, the converter will continue with clock period 3. Clock The HI5810 can operate either from its internal clock or from one externally supplied. The CLK pin functions either as the clock output or input. All converter functions are synchronized with the rising edge of the clock signal. Figure 16 shows the configuration of the internal clock. The clock output drive is low power: if used as an output, it should not have more than 1 CMOS gate load applied, and stray wiring capacitance should be kept to a minimum. The internal clock will shut down if the A/D is not restarted after a conversion. The clock could also be shut down with an open collector driver applied to the CLK pin. This should only be done during the sample portion (the first three clock periods) of a conversion cycle, and might be useful for using the device as a digital sample and hold. If an external clock is supplied to the CLK pin, it must have sufficient drive to overcome the internal clock source. The external clock can be shut off, but again, only during the sample portion of a conversion cycle. At other times, it must be above the minium frequency shown in the specifications. In the above two cases, a further restriction applies in that the clock should not be shut off during the third sample period for more than 1ms. This might cause an internal charge pump voltage to decay. If the internal or external clock was shut off during the conversion time (clock cycles 4 through 15) of the A/D, the output might be invalid due to balancing capacitor droop. An external clock must also meet the minimum tLOW and tHIGH times shown in the specifications. A violation may cause an internal miscount and invalidate the results. Except for VAA+, which is a substrate connection to VDD , all pins have protection diodes connected to VDD and VSS . Input transients above VDD or below VSS will get steered to the digital supplies. The VAA+ and VAA- terminals supply the charge balancing comparator only. Because the comparator is autobalanced between conversions, it has good low frequency supply rejection. It does not reject well at high frequencies however; VAA- should be returned to a clean analog ground and VAA+ should be RC decoupled from the digital supply as shown in Figure 17. There is approximately 50Ω of substrate impedance between VDD and VAA+. This can be used, for example, as part of a low pass RC filter to attenuate switching supply noise. A 10µF capacitor from VAA+ to ground would attenuate 30kHz noise by approximately 40dB. Note that back-to-back diodes should be placed from VDD to VAA+ to handle supply to capacitor turn-on or turn-off current spikes. Dynamic Performance Fast Fourier Transform (FFT) techniques are used to evaluate the dynamic performance of the A/D. A low distortion sine wave is applied to the input of the A/D converter. The input is sampled by the A/D and its output stored in RAM. The data is than transformed into the frequency domain with a 4096 point FFT and analyzed to evaluate the converters dynamic performance such as SNR and THD. See Typical Performance Characteristics. Signal-To-Noise Ratio The signal to noise ratio (SNR) is the measured RMS signal to RMS sum of noise at a specified input and sampling frequency. The noise is the RMS sum of all except the fundamental and the first five harmonic signals. The SNR is dependent on the number of quantization levels used in the converter. The theoretical SNR for an N-bit converter with no differential or integral linearity error is: SNR = (6.02N + 1.76)dB. For an ideal 12-bit converter the SNR is 74dB. Differential and integral linearity errors will degrade SNR. SNR = 10 Log Sinewave Signal Power Total Noise Power INTERNAL ENABLE CLK OPTIONAL EXTERNAL CLOCK CLOCK Signal-To-Noise + Distortion Ratio SINAD is the measured RMS signal to RMS sum of noise plus harmonic power and is expressed by the following. SINAD = 10 Log Sinewave Signal Power Noise + Harmonic Power (2nd - 6th) 100kΩ 18pF FIGURE 16. INTERNAL CLOCK CIRCUITRY Effective Number of Bits The effective number of bits (ENOB) is derived from the SINAD data; ENOB = SINAD - 1.76 6.02 Power Supplies and Grounding VDD and VSS are the digital supply pins: they power all internal logic and the output drivers. Because the output drivers can cause fast current spikes in the VDD and VSS lines, VSS should have a low impedance path to digital ground and VDD should be well bypassed. 6-1786 HI5810 Total Harmonic Distortion The total harmonic distortion (THD) is the ratio of the RMS sum of the second through sixth harmonic components to the fundamental RMS signal for a specified input and sampling frequency. THD = 10Log Total Harmonic Power (2nd - 6th Harmonic) Sinewave Signal Power Spurious-Free Dynamic Range The spurious-free dynamic range (SFDR) is the ratio of the fundamental RMS amplitude to the RMS amplitude of the next largest spur or spectral component. If the harmonics are buried in the noise floor it is the largest peak. SFDR = 10Log Sinewave Signal Power Highest Spurious Signal Power TABLE 2. CODE TABLE INPUT VOLTAGE † VREF+ = 4.608V VREF - = 0V (V) 4.6069 4.6058 3.4560 2.3040 1.1520 0.001125 0 BINARY OUTPUT CODE MSB DECIMAL COUNT 4095 4094 3072 2048 1024 1 0 D11 1 1 1 1 0 0 0 D10 1 1 1 0 1 0 0 D9 1 1 0 0 0 0 0 D8 1 1 0 0 0 0 0 D7 1 1 0 0 0 0 0 D6 1 1 0 0 0 0 0 D5 1 1 0 0 0 0 0 D4 1 1 0 0 0 0 0 D3 1 1 0 0 0 0 0 D2 1 1 0 0 0 0 0 D1 1 1 0 0 0 0 0 LSB D0 1 0 0 0 0 1 0 CODE DESCRIPTION Full Scale (FS) FS - 1 LSB 3/ FS 4 1/ FS 2 1/ FS 4 1 LSB Zero †The voltages listed above represent the ideal lower transition of each output code shown as a function of the reference voltage. +5V 0.1µF 10µF 0.1µF 0.01µF VAA+ VDD D11 . . . D0 DRDY OEM ANALOG INPUT VIN OEL STRT CLK VREF VAAVSS 4.7µF OUTPUT DATA VREF 4.7µF 0.1µF 0.001µF VREF+ 1.5MHz CLOCK FIGURE 17. GROUND AND SUPPLY DECOUPLING 6-1787 HI5810 Die Characteristics DIE DIMENSIONS: 3200µm x 3940µm METALLIZATION: Type: AlSi Thickness: 11kÅ ±1kÅ PASSIVATION: Type: PSG Thickness: 13kÅ ±2.5kÅ WORST CASE CURRENT DENSITY: 1.84 x 105 A/cm2 Metallization Mask Layout HI5810 D1 D0 (LSB) DRDY VDD OEL CLK D2 STRT D3 VREF - D4 D5 D6 VREF + D7 VIN D8 VAA + VAA - D9 VSS D10 D11 (MSB) OEM All Intersil semiconductor products are manufactured, assembled and tested under ISO9000 quality systems certification. Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries. For information regarding Intersil Corporation and its products, see web site http://www.intersil.com 6-1788