JAJSA35G April   2003  – May 2016 ADCS7476 , ADCS7477 , ADCS7478

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
  4. 4 改訂履歴
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics - ADCS7476
    6. 6.6 Electrical Characteristics - ADCS7477
    7. 6.7 Electrical Characteristics - ADCS7478
    8. 6.8 Timing Requirements
    9. 6.9 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
    4. 7.4 Device Functional Modes
      1. 7.4.1 Transfer Function
      2. 7.4.2 Power-Up Timing
      3. 7.4.3 Modes of Operation
        1. 7.4.3.1 Normal Mode
        2. 7.4.3.2 Start-Up Mode
        3. 7.4.3.3 Shutdown Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Analog Inputs
      2. 8.1.2 Digital Inputs and Outputs
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Power Supply Noise
    2. 9.2 Digital Output Effect Upon Noise
    3. 9.3 Power Management
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11デバイスおよびドキュメントのサポート
    1. 11.1 デバイス・サポート
      1. 11.1.1 デバイスの関連用語
    2. 11.2 コミュニティ・リソース
    3. 11.3 商標
    4. 11.4 静電気放電に関する注意事項
    5. 11.5 Glossary
  12. 12メカニカル、パッケージ、および注文情報

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)(1)(2)
MIN MAX UNIT
Supply voltage, VDD –0.3 6.5 V
Voltage on any analog pin to GND –0.3 VDD + 0.3 V
Voltage on any digital pin to GND –0.3 6.5 V
Input current at any pin (except power supply pins) ±10 mA
Soldering temperature, infrared (10 sec) 215 °C
Operating temperature, TA 150 °C
Storage temperature, Tstg –65 150 °C
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
(2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and specifications.

6.2 ESD Ratings

VALUE UNIT
V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±3500 V
Charged-device model (CDM), per JEDEC specification JESD22-C101(2) ±200
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.

6.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)
MIN MAX UNIT
VDD Supply voltage 2.7 5.25 V
Digital input pins voltage (independent of supply voltage) 2.7 5.25 V
TA Operating temperature –40 125 °C

6.4 Thermal Information

THERMAL METRIC(1) ADCS7476, ADCS7477, ADCS7478 UNIT
DBV (SOT-23)
6 PINS
RθJA Junction-to-ambient thermal resistance 184.5 °C/W
RθJC(top) Junction-to-case (top) thermal resistance 151.2 °C/W
RθJB Junction-to-board thermal resistance 29.7 °C/W
ψJT Junction-to-top characterization parameter 29.8 °C/W
ψJB Junction-to-board characterization parameter 29.1 °C/W
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report, SPRA953.

6.5 Electrical Characteristics – ADCS7476

TA = 25°C, VDD = 2.7 V to 5.25 V, fSCLK = 20 MHz, and fSAMPLE = 1 MSPS (unless otherwise noted)(1)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
STATIC CONVERTER CHARACTERISTICS
Resolution with no missing codes VDD = 2.7 V to 3.6 V, –40°C ≤ TA ≤ 125°C 12 Bits
INL Integral non-linearity VDD = 2.7 V to 3.6 V TA = 25°C ±0.4 LSB
–40°C ≤ TA ≤ 85°C ±1
VDD = 2.7 V to 3.6 V, TA = 125°C –1.1 1 LSB
DNL Differential non-linearity VDD = 2.7 V to 3.6 V TA = 25°C –0.3 0.5 LSB
–40°C ≤ TA ≤ 85°C –0.9 1
VDD = 2.7 V to 3.6 V, TA = 125°C ±1 LSB
VOFF Offset error VDD = 2.7 V to 3.6 V TA = 25°C ±0.1 LSB
−40°C ≤ TA ≤ 125°C ±1.2
GE Gain error VDD = 2.7 V to 3.6 V TA = 25°C ±0.2 LSB
–40°C ≤ TA ≤ 125°C ±1.2
DYNAMIC CONVERTER CHARACTERISTICS
SINAD Signal-to-noise plus distortion ratio fIN = 100 kHz TA = 25°C 72 dB
–40°C ≤ TA ≤ 125°C 70
SNR Signal-to-noise ratio fIN = 100 kHz TA = 25°C 72.5 dB
–40°C ≤ TA ≤ 85°C 70.8
fIN = 100 kHz, TA = 125°C 70.6 dB
THD Total harmonic distortion fIN = 100 kHz –80 dB
SFDR Spurious-free dynamic range fIN = 100 kHz 82 dB
IMD Intermodulation distortion,
second order terms		 fa = 103.5 kHz, fb = 113.5 kHz –78 dB
Intermodulation distortion,
third order terms		 fa = 103.5 kHz, fb = 113.5 kHz –78 dB
FPBW –3-dB full power bandwidth 5-V supply 11 MHz
3-V supply 8 MHz
POWER SUPPLY CHARACTERISTICS
IDD Normal mode (static) VDD = 4.75 V to 5.25 V, SCLK On or Off 2 mA
VDD = 2.7 V to 3.6 V, SCLK On or Off 1 mA
Normal mode (operational) VDD = 4.75 V to 5.25 V,
fSAMPLE = 1 MSPS		 TA = 25°C 2 mA
–40°C ≤ TA ≤ 85°C 3.5
VDD = 2.7 V to 3.6 V,
fSAMPLE = 1 MSPS		 TA = 25°C 0.6 mA
–40°C ≤ TA ≤ 85°C 1.6
Shutdown mode VDD = 5 V, SCLK Off 0.5 µA
VDD = 5 V, SCLK On 60 µA
PD Power consumption,
normal mode (operational)		 VDD = 5 V,
fSAMPLE = 1 MSPS		 TA = 25°C 10 mW
–40°C ≤ TA ≤ 85°C 17.5
VDD = 3 V,
fSAMPLE = 1 MSPS		 TA = 25°C 2 mW
–40°C ≤ TA ≤ 85°C 4.8
Power consumption,
shutdown mode		 VDD = 5 V, SCLK Off 2.5 µW
VDD = 3 V, SCLK Off 1.5 µW
ANALOG INPUT CHARACTERISTICS
VIN Input range 0 to VDD V
IDCL DC leakage current –40°C ≤ TA ≤ 85°C ±1 µA
CINA Analog input capacitance 30 pF
DIGITAL INPUT CHARACTERISTICS
VIH Input high voltage –40°C ≤ TA ≤ 85°C 2.4 V
VIL Input low voltage VDD = 5 V, –40°C ≤ TA ≤ 85°C 0.8 V
VDD = 3 V, –40°C ≤ TA ≤ 85°C 0.4 V
IIN Input current VIN = 0 V or VDD TA = 25°C ±10 nA
–40°C ≤ TA ≤ 85°C ±1 µA
CIND Digital input capacitance TA = 25°C 2 pF
–40°C ≤ TA ≤ 85°C 4
DIGITAL OUTPUT CHARACTERISTICS
VOH Output high voltage ISOURCE = 200 µA, VDD = 2.7 V to 5.25 V,
–40°C ≤ TA ≤ 85°C		 VDD – 0.2 V
VOL Output low voltage ISINK = 200 µA, –40°C ≤ TA ≤ 85°C 0.4 V
IOL TRI-STATE leakage current –40°C ≤ TA ≤ 85°C ±10 µA
COUT TRI-STATE output capacitance TA = 25°C 2 pF
–40°C ≤ TA ≤ 85°C 4
Output coding Straight (natural) binary
AC ELECTRICAL CHARACTERISTICS
fSCLK Clock frequency –40°C ≤ TA ≤ 125°C 20 MHz
DC SCLK duty cycle –40°C ≤ TA ≤ 85°C 40% 60%
tTH Track or hold acquisition time –40°C ≤ TA ≤ 85°C 400 ns
fRATE Throughput rate –40°C ≤ TA ≤ 85°C 1 MSPS
tAD Aperture delay 3 ns
tAJ Aperture jitter 30 ps
(1) Data sheet minimum and maximum specification limits are ensured by design, test, or statistical analysis.

6.6 Electrical Characteristics – ADCS7477

TA = 25°C, VDD = 2.7 V to 5.25 V, fSCLK = 20 MHz, and fSAMPLE = 1 MSPS (unless otherwise noted)(1)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
STATIC CONVERTER CHARACTERISTICS
Resolution with no missing codes –40°C ≤ TA ≤ 85°C 10 Bits
INL Integral non-linearity TA = 25°C ±0.2 LSB
–40°C ≤ TA ≤ 85°C ±0.7
DNL Differential non-linearity TA = 25°C –0.2 0.3 LSB
T–40°C ≤ TA ≤ 85°C ±0.7 ±0.7
VOFF Offset error TA = 25°C ±0.1 LSB
–40°C ≤ TA ≤ 85°C ±0.7
GE Gain error TA = 25°C ±0.2 LSB
–40°C ≤ TA ≤ 85°C ±1
DYNAMIC CONVERTER CHARACTERISTICS
SINAD Signal-to-noise plus distortion ratio fIN = 100 kHz TA = 25°C 61.7 dBFS
–40°C ≤ TA ≤ 85°C 61
SNR Signal-to-noise ratio fIN = 100 kHz 62 dB
THD Total harmonic distortion fIN = 100 kHz TA = 25°C –77 dB
–40°C ≤ TA ≤ 85°C –73
SFDR Spurious-free dynamic range fIN = 100 kHz TA = 25°C 78 dB
–40°C ≤ TA ≤ 85°C 74
IMD Intermodulation distortion,
second order terms		 fa = 103.5 kHz, fb = 113.5 kHz –78 dB
Intermodulation distortion,
third order terms		 fa = 103.5 kHz, fb = 113.5 kHz –78 dB
FPBW –3-dB full power bandwidth 5-V supply 11 MHz
3-V supply 8 MHz
POWER SUPPLY CHARACTERISTICS
IDD Normal mode (static) VDD = 4.75 V to 5.25 V, SCLK On or Off 2 mA
VDD = 2.7 V to 3.6 V, SCLK On or Off 1 mA
Normal mode (operational) VDD = 4.75 V to 5.25 V,
fSAMPLE = 1 MSPS		 TA = 25°C 2 mA
–40°C ≤ TA ≤ 85°C 3.5
VDD = 2.7 V to 3.6 V,
fSAMPLE = 1 MSPS		 TA = 25°C 0.6 mA
–40°C ≤ TA ≤ 85°C 1.6
Shutdown mode VDD = 5 V, SCLK Off 0.5 µA
VDD = 5 V, SCLK On 60
PD Power consumption,
normal mode (operational)		 VDD = 5 V,
fSAMPLE = 1 MSPS		 TA = 25°C 10 mW
–40°C ≤ TA ≤ 85°C 17.5
VDD = 3 V,
fSAMPLE = 1 MSPS		 TA = 25°C 2 mW
–40°C ≤ TA ≤ 85°C 4.8
Power consumption,
shutdown mode		 VDD = 5 V, SCLK Off 2.5 µW
VDD = 3 V, SCLK Off 1.5
ANALOG INPUT CHARACTERISTICS
VIN Input range 0 to VDD V
IDCL DC leakage current TA = −40°C to 85°C ±1 µA
CINA Analog input capacitance 30 pF
DIGITAL INPUT CHARACTERISTICS
VIH Input high voltage TA = −40°C to 85°C 2.4 V
VIL Input low voltage VDD = 5 V, –40°C ≤ TA ≤ 85°C 0.8 V
VDD = 3 V, –40°C ≤ TA ≤ 85°C 0.4 V
IIN Input current VIN = 0 V or VDD TA = 25°C ±10 nA
–40°C ≤ TA ≤ 85°C ±1 µA
CIND Digital input capacitance TA = 25°C 2 pF
–40°C ≤ TA ≤ 85°C 4
DIGITAL OUTPUT CHARACTERISTICS
VOH Output high voltage ISOURCE = 200 µA, VDD = 2.7 V to 5.25 V,
–40°C ≤ TA ≤ 85°C		 VDD – 0.2 V
VOL Output low voltage ISINK = 200 µA, –40°C ≤ TA ≤ 85°C 0.4 V
IOL TRI-STATE leakage current –40°C ≤ TA ≤ 85°C ±10 µA
COUT TRI-STATE output capacitance TA = 25°C 2 pF
–40°C ≤ TA ≤ 85°C 4
Output coding Straight (natural) binary
AC ELECTRICAL CHARACTERISTICS
fSCLK Clock frequency –40°C ≤ TA ≤ 85°C 20 MHz
DC SCLK duty cycle –40°C ≤ TA ≤ 85°C 40% 60%
tTH Track or hold acquisition time –40°C ≤ TA ≤ 85°C 400 ns
fRATE Throughput rate –40°C ≤ TA ≤ 85°C 1 MSPS
tAD Aperture delay 3 ns
tAJ Aperture jitter 30 ps
(1) Data sheet minimum and maximum specification limits are ensured by design, test, or statistical analysis.

6.7 Electrical Characteristics – ADCS7478

TA = 25°C, VDD = 2.7 V to 5.25 V, fSCLK = 20 MHz, and fSAMPLE = 1 MSPS (unless otherwise noted)(1)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
STATIC CONVERTER CHARACTERISTICS
Resolution with no missing codes –40°C ≤ TA ≤ 85°C 8 Bits
INL Integral non-linearity TA = 25°C ±0.05 LSB
–40°C ≤ TA ≤ 85°C ±0.3
DNL Differential non-linearity TA = 25°C ±0.07 LSB
–40°C ≤ TA ≤ 85°C ±0.3
VOFF Offset error TA = 25°C ±0.03 LSB
–40°C ≤ TA ≤ 85°C ±0.3
GE Gain error TA = 25°C ±0.08 LSB
–40°C ≤ TA ≤ 85°C ±0.4
Total unadjusted error TA = 25°C ±0.07 LSB
–40°C ≤ TA ≤ 85°C ±0.3
DYNAMIC CONVERTER CHARACTERISTICS
SINAD Signal-to-noise plus distortion ratio fIN = 100 kHz TA = 25°C 49.7 dB
–40°C ≤ TA ≤ 85°C 49
SNR Signal-to-noise ratio fIN = 100 kHz 49.7 dB
THD Total harmonic distortion fIN = 100 kHz TA = 25°C –77 dB
–40°C ≤ TA ≤ 85°C –65
SFDR Spurious-free dynamic range fIN = 100 kHz TA = 25°C 69 dB
–40°C ≤ TA ≤ 85°C 65
IMD Intermodulation distortion,
second order terms		 fa = 103.5 kHz, fb = 113.5 kHz –68 dB
Intermodulation distortion,
third order terms		 fa = 103.5 kHz, fb = 113.5 kHz –68 dB
FPBW –3-dB full power bandwidth 5-V supply 11 MHz
3-V supply 8 MHz
POWER SUPPLY CHARACTERISTICS
IDD Normal mode (static) VDD = 4.75 V to 5.25 V, SCLK On or Off 2 mA
VDD = 2.7 V to 3.6 V, SCLK On or Off 1 mA
Normal mode (operational) VDD = 4.75 V to 5.25 V,
fSAMPLE = 1 MSPS		 TA = 25°C 2 mA
–40°C ≤ TA ≤ 85°C 3.5
VDD = 2.7 V to 3.6 V,
fSAMPLE = 1 MSPS		 TA = 25°C 0.6 mA
–40°C ≤ TA ≤ 85°C 1.6
Shutdown mode VDD = 5 V, SCLK Off 0.5 µA
VDD = 5 V, SCLK On 60
PD Power consumption,
normal mode (operational)		 VDD = 5 V,
fSAMPLE = 1 MSPS		 TA = 25°C 10 mW
–40°C ≤ TA ≤ 85°C 17.5
VDD = 3 V,
fSAMPLE = 1 MSPS		 TA = 25°C 2 mW
–40°C ≤ TA ≤ 85°C 4.8
Power consumption,
shutdown mode		 VDD = 5 V, SCLK Off 2.5 µW
VDD = 3 V, SCLK Off 1.5
ANALOG INPUT CHARACTERISTICS
VIN Input range 0 to VDD V
IDCL DC leakage current –40°C ≤ TA ≤ 85°C ±1 µA
CINA Analog input capacitance 30 pF
DIGITAL INPUT CHARACTERISTICS
VIH Input high voltage –40°C ≤ TA ≤ 85°C 2.4 V
VIL Input low voltage VDD = 5 V, –40°C ≤ TA ≤ 85°C 0.8 V
VDD = 3 V, –40°C ≤ TA ≤ 85°C 0.4 V
IIN Digital input current VIN = 0 V or VDD TA = 25°C ±10 nA
–40°C ≤ TA ≤ 85°C ±1 µA
CIND Input capacitance TA = 25°C 2 p
–40°C ≤ TA ≤ 85°C 4
DIGITAL OUTPUT CHARACTERISTICS
VOH Output high voltage ISOURCE = 200 µA, VDD = 2.7 V to 5.25 V,
–40°C ≤ TA ≤ 85°C		 VDD − 0.2 V
VOL Output low voltage ISINK = 200 µA, –40°C ≤ TA ≤ 85°C 0.4 V
IOL TRI-STATE leakage current –40°C ≤ TA ≤ 85°C ±10 µA
COUT TRI-STATE output capacitance 2 4 pF
Output coding Straight (natural) binary
AC ELECTRICAL CHARACTERISTICS
fSCLK Clock frequency –40°C ≤ TA ≤ 85°C 20 MHz
DC SCLK duty cycle –40°C ≤ TA ≤ 85°C 40% 60%
tTH Track or hold acquisition time –40°C ≤ TA ≤ 85°C 400 ns
fRATE Throughput rate –40°C ≤ TA ≤ 85°C (see Application Information) 1 MSPS
tAD Aperture delay 3 ns
tAJ Aperture jitter 30 ps
(1) Data sheet min/max specification limits are ensured by design, test, or statistical analysis.

6.8 Timing Requirements

–40°C ≤ TA ≤ 85°C, VDD = 2.7 V to 5.25 V, and fSCLK = 20 MHz (unless otherwise noted)(1)
PARAMETER CONDITIONS MIN TYP MAX UNIT
tCONVERT TA = 25°C 16 × tSCLK
tQUIET Quiet time(2) 50 ns
t1 Minimum CS pulse width 10 ns
t2 CS to SCLK setup time 10 ns
t3 Delay from CS until SDATA TRI-STATE disabled (3) 20 ns
t4 Data access time after SCLK falling edge(4) VDD = 2.7 V to 3.6 V 40 ns
VDD = 4.75 V to 5.25 V 20 ns
t5 SCLK low pulse width 0.4 × tSCLK ns
t6 SCLK high pulse width 0.4 × tSCLK ns
t7 SCLK to data valid hold time VDD = 2.7 V to 3.6 V 7 ns
VDD = 4.75 V to 5.25 V 5 ns
t8 SCLK falling edge to SDATA high impedance (5) VDD = 2.7 V to 3.6 V 6 25 ns
VDD = 4.75 V to 5.25 V 5 25 ns
tPOWER-UP Power-up time from full power down TA = 25°C 1 µs
(1) All input signals are specified as tr = tf = 5 ns (10% to 90% VDD) and timed from 1.6 V.
(2) Minimum quiet time required between bus relinquish and start of next conversion.
(3) Measured with the load circuit (Figure 1), and defined as the time taken by the output to cross 1 V.
(4) Measured with the load circuit (Figure 1), and defined as the time taken by the output to cross 1 V or 2 V.
(5) t8 is derived from the time taken by the outputs to change by 0.5 V with the loading circuit (Figure 1). The measured number is then adjusted to remove the effects of charging or discharging the 25-pF capacitor. This means t8 is the true bus relinquish time, independent of the bus loading.
ADCS7476 ADCS7477 ADCS7478 20057708.png Figure 1. Timing Test Circuit
ADCS7476 ADCS7477 ADCS7478 20057702.png Figure 2. ADCS7476 Serial Interface Timing Diagram
ADCS7476 ADCS7477 ADCS7478 20057703.png Figure 3. ADCS7477 Serial Interface Timing Diagram
ADCS7476 ADCS7477 ADCS7478 20057704.png Figure 4. ADCS7478 Serial Interface Timing Diagram

6.9 Typical Characteristics

TA = 25°C, VDD = 3 V, fSAMPLE = 1 MSPS, fSCLK = 20 MHz, and fIN = 100 kHz (unless otherwise noted)
ADCS7476 ADCS7477 ADCS7478 20057706.png Figure 5. ADCS7476 DNL
ADCS7476 ADCS7477 ADCS7478 20057707.png Figure 7. ADCS7476 Spectral Response at 100-kHz Input
ADCS7476 ADCS7477 ADCS7478 20057751.png Figure 9. ADCS7476 THD vs Input Frequency, 600 KSPS
ADCS7476 ADCS7477 ADCS7478 20057753.png Figure 11. ADCS7476 SINAD vs Input Frequency, 600 KSPS
ADCS7476 ADCS7477 ADCS7478 20057756.png Figure 13. ADCS7476 SNR vs fSCLK
ADCS7476 ADCS7477 ADCS7478 20057770.png Figure 15. ADCS7477 DNL
ADCS7476 ADCS7477 ADCS7478 20057772.png Figure 17. ADCS7477 Spectral Response at 100-kHz Input
ADCS7476 ADCS7477 ADCS7478 20057774.png Figure 19. ADCS7477 SINAD vs fSCLK
ADCS7476 ADCS7477 ADCS7478 20057761.png Figure 21. ADCS7478 INL
ADCS7476 ADCS7477 ADCS7478 20057763.png Figure 23. ADCS7478 SNR vs fSCLK
ADCS7476 ADCS7477 ADCS7478 20057705.png Figure 6. ADCS7476 INL
ADCS7476 ADCS7477 ADCS7478 20057750.png Figure 8. ADCS7476 THD vs Source Impedance
ADCS7476 ADCS7477 ADCS7478 20057752.png Figure 10. ADCS7476 THD vs Input Frequency, 1 MSPS
ADCS7476 ADCS7477 ADCS7478 20057754.png Figure 12. ADCS7476 SINAD vs Input Frequency, 1 MSPS
ADCS7476 ADCS7477 ADCS7478 20057757.png Figure 14. ADCS7476 SINAD vs fSCLK
ADCS7476 ADCS7477 ADCS7478 20057771.png Figure 16. ADCS7477 INL
ADCS7476 ADCS7477 ADCS7478 20057773.png Figure 18. ADCS7477 SNR vs fSCLK
ADCS7476 ADCS7477 ADCS7478 20057760.png Figure 20. ADCS7478 DNL
ADCS7476 ADCS7477 ADCS7478 20057762.png Figure 22. ADCS7478 Spectral Response at 100-kHz Input
ADCS7476 ADCS7477 ADCS7478 20057764.png Figure 24. ADCS7478 SINAD vs fSCLK