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LTC2302CDD#TRPBF

LTC2302CDD#TRPBF

  • 厂商:

    AD(亚德诺)

  • 封装:

    WFDFN10

  • 描述:

    IC ADC 12BIT SAR 10DFN

  • 数据手册
  • 价格&库存
LTC2302CDD#TRPBF 数据手册
LTC2302/LTC2306 Low Noise, 500ksps, 1-/2-Channel, 12-Bit ADCs Features Description 12-Bit Resolution 500ksps Sampling Rate Low Noise: SINAD = 72.8dB Guaranteed No Missing Codes Single 5V Supply Auto-Shutdown Scales Supply Current with Sample Rate n Low Power: 14mW at 500ksps 70µW at 1ksps 35µW Sleep Mode n 1-Channel (LTC2302) and 2-Channel (LTC2306) Versions n Unipolar or Bipolar Input Ranges (Software Selectable) n Internal Conversion Clock n SPI/MICROWIRE Compatible Serial Interface n Separate Output Supply OV DD (2.7V to 5.25V) n Software Compatible with the LTC2308 n 10-Pin (3mm × 3mm) DFN Package The LTC®2302/LTC2306 are low noise, 500ksps, 1‑/2‑chan‑ nel, 12-bit ADCs with an SPI/MICROWIRE compatible serial interface. These ADCs include a fully differential sample-and-hold circuit to reduce common mode noise. The internal conversion clock allows the external serial output data clock (SCK) to operate at any frequency up to 40MHz. Applications TYPE Int Reference Ext Reference n n n n n n n n n n n n The LTC2302/LTC2306 operate from a single 5V supply and draw just 2.8mA at a sample rate of 500ksps. The auto-shutdown feature reduces the supply current to 14µA at a sample rate of 1ksps. The LTC2302/LTC2306 are packaged in a tiny 10-pin 3mm × 3mm DFN. The low power consumption and small size make the LTC2302/LTC2306 ideal for battery-operated and portable applications, while the 4-wire SPI compat‑ ible serial interface makes these ADCs a good match for isolated or remote data acquisition systems. High Speed Data Acquisition Industrial Process Control Motor Control Accelerometer Measurements Battery-Operated Instruments Isolated and/or Remote Data Acquisition 1 NUMBER OF INPUT CHANNELS 2 LTC2302 8192 Point FFT, fIN = 1kHz (LTC2306) 5V 2.7V TO 5.25V 0.1µF OVDD VDD + – 0.1µF LTC2302 LTC2306 SDI 12-BIT 500ksps ADC SERIAL PORT SDO SCK SERIAL DATA LINK TO ASIC, PLD, MPU, DSP OR SHIFT REGISTER CONVST PIN NAMES IN PARENTHESIS REFER TO LTC2302 GND VREF 0.1µF 10µF 23026 TA01 MAGNITUDE (dB) 10µF ANALOG INPUT MUX LTC2306 L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Typical Application ANALOG INPUTS CH0 (IN+) 0V TO 4.096V UNIPOLAR CH1 (IN–) ±2.048V BIPOLAR 8 LTC2308 0 –10 –20 –30 –40 –50 –60 –70 –80 –90 –100 –110 –120 –130 –140 fSMPL = 500kHz SINAD = 72.8dB THD = –88.7dB 0 50 100 150 FREQUENCY (kHz) 200 250 23026 TA01b 23026fb For more information www.linear.com/LTC2302 1 LTC2302/LTC2306 Absolute Maximum Ratings (Notes 1, 2) Supply Voltage (VDD, OVDD)......................... –0.3V to 6V Analog Input Voltage (Note 3) CH0(IN+)-CH1(IN–), REF ...............................(GND – 0.3V) to (VDD + 0.3V) Digital Input Voltage (Note 3)..............................(GND – 0.3V) to (VDD + 0.3V) Digital Output Voltage .... (GND – 0.3V) to (OVDD + 0.3V) Power Dissipation............................................... 500mW Operating Temperature Range LTC2302C/LTC2306C............................... 0°C to 70°C LTC2302I/LTC2306I..............................–40°C to 85°C Storage Temperature Range...................–65°C to 150°C Pin Configuration LTC2302 TOP VIEW LTC2306 TOP VIEW 10 OVDD SDO 1 10 OVDD SDO 1 9 SCK CONVST 2 8 SDI IN+ 4 VDD 3 7 GND CH0 4 7 GND IN– 5 6 VREF CH1 5 6 VREF CONVST 2 VDD 3 11 DD PACKAGE 10-LEAD (3mm × 3mm) PLASTIC DFN 9 SCK 11 8 SDI DD PACKAGE 10-LEAD (3mm × 3mm) PLASTIC DFN TJMAX = 150°C, θJA = 43°C/W EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB TJMAX = 150°C, θJA = 43°C/W EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB order information LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2302CDD#PBF LTC2302CDD#TRPBF LDGV 10-Lead (3mm × 3mm) Plastic DFN 0°C to 70°C LTC2302IDD#PBF LTC2302IDD#TRPBF LDGV 10-Lead (3mm × 3mm) Plastic DFN –40°C to 85°C LTC2306CDD#PBF LTC2306CDD#TRPBF LDGW 10-Lead (3mm × 3mm) Plastic DFN 0°C to 70°C LTC2306IDD#PBF LTC2306IDD#TRPBF LDGW 10-Lead (3mm × 3mm) Plastic DFN –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ 2 23026fb For more information www.linear.com/LTC2302 LTC2302/LTC2306 CONVERTER AND MULTIPLEXER CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Notes 4, 5) PARAMETER CONDITIONS MIN Resolution (No Missing Codes) Integral Linearity Error l (Note 6) ±1 LSB l ±0.25 ±1 LSB l ±1 ±6 LSB (Note 7) l 0.002 ±1 LSB/°C ±6 0.002 Unipolar Zero Error Match (LTC2306) (Note 8) l (Note 8) l Bipolar Full-Scale Error Drift Unipolar Full-Scale Error Bits ±0.3 Unipolar Zero Error Drift Bipolar Full-Scale Error UNITS l Bipolar Zero Error Drift Unipolar Zero Error MAX (Note 7) Differential Linearity Error Bipolar Zero Error TYP 12 LSB LSB/°C ±0.3 ±3 LSB ±1.5 ±8 LSB 0.05 ±1.2 Unipolar Full-Scale Error Drift 0.05 Unipolar Full-Scale Error Match (LTC2306) ±0.3 LSB/°C ±6 LSB LSB/°C ±3 LSB ANALOG INPUT The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 4) SYMBOL PARAMETER CONDITIONS MAX UNITS VIN+ Absolute Input Range (CH0, CH1, IN+) (Note 9) l –0.05 VREF V – Absolute Input Range (CH0, CH1, IN–) Unipolar (Note 9) Bipolar (Note 9) l l –0.05 –0.05 0.25 • VREF 0.75 • VREF V V VIN = VIN+ – VIN– (Unipolar) VIN = VIN+ – VIN– (Bipolar) l l VIN VIN+ – VIN– Input Differential Voltage Range IIN Analog Input Leakage Current CIN Analog Input Capacitance CMRR Input Common Mode Rejection Ratio MIN TYP 0 to VREF ±VREF/2 V V ±1 l Sample Mode Hold Mode µA 55 5 pF pF 70 dB REFERENCE INPUT The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 4) SYMBOL PARAMETER CONDITIONS VREF Input Range IREF Reference Input Current CREF Reference Input Capacitance MIN l fSMPL = 0ksps, VREF = 4.096V fSMPL = 500ksps, VREF = 4.096V l l TYP 0.1 50 230 55 MAX UNITS VDD V 80 260 µA µA pF 23026fb For more information www.linear.com/LTC2302 3 LTC2302/LTC2306 DYNAMIC ACCURACY The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. AIN = –1dBFS. (Notes 4, 10) SYMBOL PARAMETER CONDITIONS MIN TYP SINAD Signal-to-(Noise + Distortion) Ratio fIN = 1kHz l 71 72.8 dB SNR Signal-to-Noise Ratio fIN = 1kHz l 71 73.2 dB THD Total Harmonic Distortion fIN = 1kHz, First 5 Harmonics l SFDR Spurious Free Dynamic Range fIN = 1kHz l –88 79 MAX UNITS –78 dB 89 dB Channel-to-Channel Isolation fIN = 1kHz –109 dB Full Linear Bandwidth (Note 11) 700 kHz 25 MHz –3dB Input Linear Bandwidth Aperture Delay Transient Response Full-Scale Step 13 ns 240 ns DIGITAL INPUTS AND DIGITAL OUTPUTS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 4) SYMBOL PARAMETER CONDITIONS VIH High Level Input Voltage VDD = 5.25V l MIN TYP MAX UNITS 2.4 V VIL Low Level Input Voltage VDD = 4.75V l 0.8 V IIN High Level Input Current VIN = VDD l ±10 µA CIN Digital Input Capacitance VOH High Level Output Voltage VOL Low Level Output Voltage OVDD = 4.75V, IOUT = –10µA OVDD = 4.75V, IOUT = –200µA l OVDD = 4.75V, IOUT = 160µA OVDD = 4.75V, IOUT = 1.6mA l l 4 5 pF 4.74 V V 0.05 0.4 V V ±10 µA IOZ Hi-Z Output Leakage VOUT = 0V to OVDD, CONVST High COZ Hi-Z Output Capacitance CONVST High 15 pF ISOURCE Output Source Current VOUT = 0V –10 mA ISINK Output Sink Current VOUT = OVDD 10 mA POWER REQUIREMENTS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 4) SYMBOL PARAMETER VDD Supply Voltage OVDD Output Driver Supply Voltage IDD Supply Current Sleep Mode PD Power Dissipation Sleep Mode 4 CONDITIONS CL = 25pF CONVST = 5V, Conversion Done MIN TYP MAX UNITS l 4.75 5 5.25 V l 2.7 l l 2.8 7 14 35 5.25 V 3.5 15 mA µA mW µW 23026fb For more information www.linear.com/LTC2302 LTC2302/LTC2306 TIMING CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 4) SYMBOL PARAMETER MAX UNITS fSMPL(MAX) Maximum Sampling Frequency CONDITIONS l MIN 500 kHz fSCK Shift Clock Frequency l 40 MHz tWHCONV CONVST High Time tHD Hold Time SDI After SCK↑ (Note 9) TYP l 20 ns l 2.5 ns tSUDI Setup Time SDI Stable Before SCK↑ l 0 ns tWHCLK SCK High Time fSCK = fSCK(MAX) l 10 ns tWLCLK SCK Low Time fSCK = fSCK(MAX) l 10 ns tWLCONVST CONVST Low Time During Data Transfer (Note 9) l 410 ns tHCONVST Hold Time CONVST Low After Last SCK↓ (Note 9) l 20 ns tCONV Conversion Time tACQ Acquisition Time 7th SCK↑ to CONVST↑ (Note 9) l tdDO SDO Data Valid After SCK↓ CL = 25pF (Note 9) l thDO SDO Hold Time SCK↓ CL = 25pF l ten SDO Valid After CONVST↓ CL = 25pF tdis Bus Relinquish Time CL = 25pF 1.3 1.6 µs 10.8 12.5 ns l 11 15 ns l 11 15 ns l 240 ns 4 ns tr SDO Rise Time CL = 25pF 4 ns tf SDO Fall Time CL = 25pF 4 ns tCYC Total Cycle Time 2 µs Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: All voltage values are with respect to ground with VDD and OVDD wired together (unless otherwise noted). Note 3: When these pin voltages are taken below ground or above VDD, they will be clamped by internal diodes. These products can handle input currents greater than 100mA below ground or above VDD without latchup. Note 4: VDD = 5V, OVDD = 5V, VREF = 4.096V, fSMPL = 500ksps, unless otherwise specified. Note 5: Linearity, offset and full-scale specifications apply for a singleended analog input with respect to GND for the LTC2306 and IN+ with respect to IN – tied to GND for the LTC2302. Note 6: Integral nonlinearity is defined as the deviation of a code from a straight line passing through the actual endpoints of the transfer curve. The deviation is measured from the center of the quantization band. Note 7: Bipolar zero error is the offset voltage measured from –0.5LSB when the output code flickers between 0000 0000 0000 and 1111 1111 1111. Unipolar zero error is the offset voltage measured from +0.5LSB when the output code flickers between 0000 0000 0000 and 0000 0000 0001. Note 8: Full-scale bipolar error is the worst-case of –FS or +FS untrimmed deviation from ideal first and last code transitions and includes the effect of offset error. Unipolar full-scale error is the deviation of the last code transition from ideal and includes the effect of offset error. Note 9: Guaranteed by design, not subject to test. Note 10: All specifications in dB are referred to a full-scale ±2.048V input with a 4.096V reference voltage. Note 11: Full linear bandwidth is defined as the full-scale input frequency at which the SINAD degrades to 60dB or 10 bits of accuracy. 23026fb For more information www.linear.com/LTC2302 5 LTC2302/LTC2306 Typical Performance Characteristics (LTC2302) TA = 25°C, VDD = OVDD = 5V, VREF = 4.096V, fSMPL = 500ksps, unless otherwise noted. 1.00 1.00 0.75 0.75 0.50 0.50 0.25 0.25 0 –0.25 0 –0.25 –0.50 –0.50 –0.75 –0.75 –1.00 1kHz Sine Wave 8192 Point FFT Plot MAGNITUDE (dB) Differential Nonlinearity vs Output Code DNL (LSB) INL (LSB) Integral Nonlinearity vs Output Code 0 2048 1024 3072 –1.00 4096 0 1024 OUTPUT CODE 2048 4096 3072 0 –10 –20 –30 –40 –50 –60 –70 –80 –90 –100 –110 –120 –130 –140 SNR = 73.2dB SINAD = 72.8dB THD = –89.5dB 0 50 100 150 23026 G01 SINAD vs Input Frequency 80 80 75 75 70 70 250 23026 G03 23026 G02 SNR vs Input Frequency 200 FREQUENCY (kHz) OUTPUT CODE THD vs Input Frequency –60 –65 65 THD (dB) SINAD (dB) SNR (dB) –70 65 60 60 55 55 –75 –80 –85 –90 50 1 10 100 FREQUENCY (kHz) 1000 50 –95 10 100 FREQUENCY (kHz) 1 1000 23026 G04 1000 23026 G06 Supply Current vs Temperature 3.8 3.0 3.6 SUPPLY CURRENT (mA) SUPPLY CURRENT (mA) 10 100 FREQUENCY (kHz) 4.0 3.5 2.5 2.0 1.5 1.0 3.4 3.2 3.0 2.8 2.6 2.4 0.5 2.2 1 10 100 SAMPLING FREQUENCY (ksps) 1000 2.0 –50 23026 G07 6 1 23026 G05 Supply Current vs Sampling Frequency 0 –100 –25 50 25 0 75 TEMPERATURE (°C) 100 125 23026 G08 23026fb For more information www.linear.com/LTC2302 LTC2302/LTC2306 Typical Performance Characteristics (LTC2302) TA = 25°C, VDD = OVDD = 5V, VREF = 4.096V, fSMPL = 500ksps, unless otherwise noted. Analog Input Leakage Current vs Temperature Sleep Current vs Temperature 1000 9 900 INPUT LEAKAGE CURRENT (nA) 10 SLEEP CURRENT (µA) 8 7 6 5 4 3 2 800 700 600 500 400 300 200 100 1 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 0 –50 125 –25 50 25 0 75 TEMPERATURE (°C) Offset Error vs Temperature Full-Scale Error vs Temperature 2.5 2.0 2.0 1.5 FULL-SCALE ERROR (LSB) OFFSET ERROR (LSB) 1.5 1.0 BIPOLAR 0 UNIPOLAR –0.5 –1.0 –1.5 BIPOLAR 1.0 UNIPOLAR 0.5 0 –0.5 –1.0 –1.5 –2.0 –2.5 –50 125 23026 G10 23026 G09 0.5 100 –25 50 25 0 75 TEMPERATURE (°C) 100 125 –2.0 –50 –25 23026 G11 75 50 25 TEMPERATURE (°C) 0 100 125 23026 G12 23026fb For more information www.linear.com/LTC2302 7 LTC2302/LTC2306 Typical Performance Characteristics (LTC2306) TA = 25°C, VDD = OVDD = 5V, VREF = 4.096V, fSMPL = 500ksps, unless otherwise noted. 1.00 1.00 0.75 0.75 0.50 0.50 0.25 0.25 0 –0.25 0 –0.25 –0.50 –0.50 –0.75 –0.75 –1.00 1kHz Sine Wave 8192 Point FFT Plot MAGNITUDE (dB) Differential Nonlinearity vs Output Code DNL (LSB) INL (LSB) Integral Nonlinearity vs Output Code 0 2048 1024 3072 4096 –1.00 0 1024 OUTPUT CODE 2048 4096 3072 0 –10 –20 –30 –40 –50 –60 –70 –80 –90 –100 –110 –120 –130 –140 SNR = 73.2dB SINAD = 72.8dB THD = –88.7dB 0 50 100 150 23026 G13 SINAD vs Input Frequency SNR vs Input Frequency 80 75 75 70 70 250 23026 G15 23026 G14 80 200 FREQUENCY (kHz) OUTPUT CODE THD vs Input Frequency –60 –65 65 THD (dB) SINAD (dB) SNR (dB) –70 65 60 60 55 55 –75 –80 –85 –90 50 1 10 100 FREQUENCY (kHz) 1000 50 –95 10 100 FREQUENCY (kHz) 1 1000 23026 G16 1000 23026 G18 Supply Current vs Temperature 3.8 3.0 3.6 SUPPLY CURRENT (mA) SUPPLY CURRENT (mA) 10 100 FREQUENCY (kHz) 4.0 3.5 2.5 2.0 1.5 1.0 3.4 3.2 3.0 2.8 2.6 2.4 0.5 2.2 1 10 100 SAMPLING FREQUENCY (ksps) 1000 2.0 –50 –25 23026 G19 8 1 23026 G17 Supply Current vs Sampling Frequency 0 –100 50 25 0 75 TEMPERATURE (°C) 100 125 23026 G20 23026fb For more information www.linear.com/LTC2302 LTC2302/LTC2306 Typical Performance Characteristics (LTC2306) TA = 25°C, VDD = OVDD = 5V, VREF = 4.096V, fSMPL = 500ksps, unless otherwise noted. Analog Input Leakage Current vs Temperature Sleep Current vs Temperature 1000 9 900 INPUT LEAKAGE CURRENT (nA) 10 SLEEP CURRENT (µA) 8 7 6 5 4 3 2 1 800 700 600 500 400 300 200 100 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 0 –50 125 –25 50 25 0 75 TEMPERATURE (°C) 23026 G21 2.0 1.5 1.5 FULL-SCALE ERROR (LSB) OFFSET ERROR (LSB) Full-Scale Error vs Temperature 2.0 1.0 0.5 UNIPOLAR BIPOLAR –0.5 –1.0 –1.5 –2.0 –50 –25 125 23026 G22 Offset Error vs Temperature 0 100 1.0 0.5 UNIPOLAR 0 –0.5 BIPOLAR –1.0 –1.5 75 50 25 TEMPERATURE (°C) 0 100 125 –2.0 –50 –25 23026 G23 75 50 25 TEMPERATURE (°C) 0 100 125 23026 G24 23026fb For more information www.linear.com/LTC2302 9 LTC2302/LTC2306 Pin Functions LTC2302 LTC2306 SDO (Pin 1): Three-State Serial Data Out. SDO outputs the data from the previous conversion. SDO is shifted out serially on the falling edge of each SCK pulse. SDO is enabled by a low level on CONVST. SDO (Pin 1): Three-State Serial Data Out. SDO outputs the data from the previous conversion. SDO is shifted out serially on the falling edge of each SCK pulse. SDO is enabled by a low level on CONVST. CONVST (Pin 2): Conversion Start. A rising edge at CONVST begins a conversion. For best performance, ensure that CONVST returns low within 40ns after the conversion starts or after the conversion ends. CONVST (Pin 2): Conversion Start. A rising edge at CONVST begins a conversion. For best performance, ensure that CONVST returns low within 40ns after the conversion starts or after the conversion ends. VDD (Pin 3): 5V Supply. The range of VDD is 4.75V to 5.25V. Bypass VDD to GND with a 0.1µF ceramic capacitor and a 10µF tantalum capacitor in parallel. VDD (Pin 3): 5V Supply. The range of VDD is 4.75V to 5.25V. Bypass VDD to GND with a 0.1µF ceramic capacitor and a 10µF tantalum capacitor in parallel. IN+, IN – (Pin 4, Pin 5): Positive (IN+) and Negative (IN–) Differential Analog Inputs. CH0, CH1 (Pin 4, Pin 5): Channel 0 and Channel 1 Analog Inputs. CH0, CH1 can be configured as single-ended or differential input channels. See the Analog Input Multi‑ plexer section. VREF (Pin 6): Reference Input. Connect an external refer‑ ence at VREF . The range of the external reference is 0.1V to VDD. Bypass to GND with a minimum 10µF tantalum capacitor in parallel with a 0.1µF ceramic capacitor. GND (Pin 7): Ground. All GND pins must be connected to a solid ground plane. SDI (Pin 8): Serial Data Input. The SDI serial bit stream configures the ADC and is latched on the rising edge of the first 6 SCK pulses. SCK (Pin 9): Serial Data Clock. SCK synchronizes the serial data transfer. The serial data input at SDI is latched on the rising edge of SCK. The serial data output at SDO transitions on the falling edge of SCK. OVDD (Pin 10): Output Driver Supply. Bypass OVDD to GND with a 0.1µF ceramic capacitor close to the pin. The range of OVDD is 2.7V to 5.25V. Exposed Pad (Pin 11): Exposed Pad Ground. Must be soldered directly to ground plane. 10 VREF (Pin 6): Reference Input. Connect an external refer‑ ence at VREF .The range of the external reference is 0.1V to VDD. Bypass to GND with a minimum 10µF tantalum capacitor in parallel with a 0.1µF ceramic capacitor. GND (Pin 7): Ground. All GND pins must be connected to a solid ground plane. SDI (Pin 8): Serial Data Input. The SDI serial bit stream configures the ADC and is latched on the rising edge of the first 6 SCK pulses. SCK (Pin 9): Serial Data Clock. SCK synchronizes the serial data transfer. The serial data input at SDI is latched on the rising edge of SCK. The serial data output at SDO transitions on the falling edge of SCK. OVDD (Pin 10): Output Driver Supply. Bypass OVDD to OGND with a 0.1µF ceramic capacitor close to the pin. The range of OVDD is 2.7V to 5.5V. Exposed Pad (Pin 11): Exposed Pad Ground. Must be soldered directly to ground plane. 23026fb For more information www.linear.com/LTC2302 LTC2302/LTC2306 Block Diagram OVDD VDD LTC2302 LTC2306 CH0 (IN+) CH1 (IN–) ANALOG INPUT MUX + – SDI 12-BIT 500ksps ADC SERIAL PORT SDO SCK CONVST VREF PIN NAMES IN PARENTHESIS REFER TO LTC2302 23026 BD GND test circuits Load Circuit for tdis Waveform 1 Load Circuit for tdis Waveform 2, ten VDD 3k SDO SDO TEST POINT CL TEST POINT 3k 23026 TC01 CL 23026 TC02 23026fb For more information www.linear.com/LTC2302 11 LTC2302/LTC2306 timing Diagrams Voltage Waveforms for SDO Delay Times, tdDO and thDO SCK Voltage Waveforms for tdis VIH CONVST VIL tdDO thDO VOH SDO VOL 23026 TD01 SDO WAVEFORM 1 (SEE NOTE 1) 90% tdis SDO WAVEFORM 2 (SEE NOTE 2) 10% NOTE 1: WAVEFORM 1 IS FOR AN OUTPUT WITH INTERNAL CONDITIONS SUCH THAT THE OUTPUT IS HIGH UNLESS DISABLED BY THE OUTPUT CONTROL NOTE 2: WAVEFORM 2 IS FOR AN OUTPUT WITH INTERNAL CONDITIONS SUCH THAT THE OUTPUT IS LOW UNLESS DISABLED BY THE OUTPUT CONTROL 23026 TD02 tWLCLK (SCK Low Time) tWHCLK (SCK High Time) tHD (Hold Time SDI After SCK↑) tSUDI (Setup Time SDI Stable Before SCK↑) tWLCLK Voltage Waveforms for ten CONVST tWHCLK SDO 23026 TD04 ten SCK tHD Voltage Waveforms for SDO Rise and Fall Times tr, tf SDI tSUDI 23026 TD03 VOH SDO VOL tr 12 tf 23004 TD05 23026fb For more information www.linear.com/LTC2302 LTC2302/LTC2306 Applications Information Overview The LTC2302/LTC2306 are low noise, 500ksps, 1-/2-chan‑ nel, 12-bit successive approximation register (SAR) A/D converters. The LTC2306 includes a 2-channel analog input multiplexer (MUX) while the LTC2302 includes an input MUX that allows the polarity of the differential input to be selected. Both ADCs include an SPI-compatible se‑ rial port for easy data transfers and can operate in either unipolar or bipolar mode. Unipolar mode should be used for single-ended operation with the LTC2306, since singleended input signals are always referenced to GND. The LTC2302/LTC2306 can be put into a power-down sleep mode during idle periods to save power. Conversions are initiated by a rising edge on the CONVST input. Once a conversion cycle has begun, it cannot be restarted. Between conversions, a 6-bit input word (DIN) at the SDI input configures the MUX and programs vari‑ ous modes of operation. As the DIN bits are shifted in, data from the previous conversion is shifted out on SDO. After the 6 bits of the DIN word have been shifted in, the ADC begins acquiring the analog input in preparation for the next conversion as the rest of the data is shifted out. The acquire phase requires a minimum time of 240ns for the sample-and-hold capacitors to acquire the analog input signal. During the conversion, the internal 12-bit capacitive charge-redistribution DAC output is sequenced through a successive approximation algorithm by the SAR starting from the most significant bit (MSB) to the least significant bit (LSB). The sampled input is successively compared with binary weighted charges supplied by the capacitive DAC using a differential comparator. At the end of a conver‑ sion, the DAC output balances the analog input. The SAR contents (a 12-bit data word) that represent the sampled analog input are loaded into 12 output latches that allow the data to be shifted out. Programming the LTC2306 and LTC2302 The software compatible LTC2302/LTC2306/LTC2308 family features a 6-bit DIN word to program various modes of operation. Don’t care bits (X) are ignored. The SDI data bits are loaded on the rising edge of SCK, with the S/D bit loaded on the first rising edge (see Figure 6 in the Timing and Control section). The input data word for the LTC2306 is defined as follows: S/D O/S X X UNI X S/D = SINGLE-ENDED/DIFFERENTIAL BIT O/S = ODD/SIGN BIT UNI = UNIPOLAR/BIPOLAR BIT X = DON’ T CARE For the LTC2302, the input data word is defined as: X O/S X X UNI X 23026fb For more information www.linear.com/LTC2302 13 LTC2302/LTC2306 Applications Information Analog Input Multiplexer The analog input MUX is programmed by the S/D and O/S bits of the DIN word for the LTC2306 and the O/S bit of the DIN word for the LTC2302. Table 1 and Table 2 list MUX configurations for all combinations of the configuration bits. Figure 1a shows several possible MUX configurations and Figure 1b shows how the MUX can be reconfigured from one conversion to the next. 1 Differential + (–) – (+) { 2 Single-Ended + + CH0 CH1 S/D O/S 0 0 + – 0 1 – + 1 0 + 1 1 CH0 CH1 + WITH RESPECT TO GND NOTE: UNIPOLAR MODE SHOULD BE USED FOR SINGLE-ENDED OPERATION, SINCE INPUT SIGNALS ARE ALWAYS REFERENCED TO GND Table 2. Channel Configuration for the LTC2302 CH0 CH1 LTC2306 Table 1. Channel Configuration for the LTC2306 LTC2306 O/S IN+ IN– 0 + – 1 – + (–) GND Driving the Analog Inputs 1 Differential + (–) – (+) { IN+ IN– LTC2302 23026 F01a Figure 1a. Example MUX Configurations 1st Conversion + –{ CH0 CH1 LTC2306 2nd Conversion + + CH0 CH1 LTC2306 (–) GND The analog inputs of the LTC2302/LTC2306 are easy to drive. Each of the analog inputs of the LTC2306 (CH0 and CH1) can be used as a single-ended input relative to GND or as a differential pair. The analog inputs of the LTC2302 (IN+, IN–) are always configured as a differential pair. Regardless of the MUX configuration, the “+” and “–” inputs are sampled at the same instant. Any unwanted signal that is common to both inputs will be reduced by the common mode rejection of the sample-and-hold cir‑ cuit. The inputs draw only one small current spike while charging the sample-and-hold capacitors during the acquire mode. In conversion mode, the analog inputs draw only a small leakage current. If the source impedance of the driving circuit is low, the ADC inputs can be driven directly. Otherwise, more acquisition time should be allowed for a source with higher impedance. 23026 F01b Figure 1b. Changing the MUX Assignment “On the Fly” 14 23026fb For more information www.linear.com/LTC2302 LTC2302/LTC2306 Applications Information Reference A low noise, stable reference is required to ensure full performance. The LT®1790 and LT6660 are adequate for most applications. The LT6660 is available in 2.5V, 3V, 3.3V and 5V versions, and the LT1790 is available in 1.25V, 2.048V, 2.5V, 3V, 3.3V, 4.096V and 5V versions. The exceptionally low input noise allows the input range to be optimized for the application by changing the reference voltage. The VREF input must be decoupled with a 10µF capacitor in parallel with a 0.1µF capacitor, so verify that the device providing the reference voltage is stable with capacitive loads. If the voltage reference is 5V and can supply 5mA, it can be used for both VREF and VDD. VDD must be connected to a clean analog supply, and a quiet 5V reference voltage makes a convenient supply for this purpose. Input Filtering The noise and distortion of the input amplifier and other circuitry must be considered since they will add to the ADC noise and distortion. Therefore, noisy input circuitry should be filtered prior to the analog inputs to minimize noise. A simple 1-pole RC filter is sufficient for many applications. VIN RSOURCE INPUT (CH0, CH1 IN+, IN–) C1 The analog inputs of the LTC2302/LTC2306 can be modeled as a 55pF capacitor (CIN) in series with a 100Ω resistor (RON) as shown in Figure 2a. CIN gets switched to the selected input once during each conversion. Large filter RC time constants will slow the settling of the inputs. It is important that the overall RC time constants be short enough to allow the analog inputs to completely settle to 12-bit resolution within the acquisition time (tACQ) if DC accuracy is important. When using a filter with a large CFILTER value (e.g., 1µF), the inputs do not completely settle and the capacitive in‑ put switching currents are averaged into a net DC current (IDC). In this case, the analog input can be modeled by an equivalent resistance (REQ = 1/(fSMPL • CIN)) in series with an ideal voltage source (VREF/2) as shown in Figure 2b. The magnitude of the DC current is then approximately IDC = (VIN – VREF/2)/REQ, which is roughly proportional to VIN. To prevent large DC drops across the resistor RFILTER, a filter with a small resistor and large capacitor should be chosen. When running at the minimum cycle time of 2µs, the input current equals 106µA at VIN = 5V, which amounts to a full-scale error of 0.5LSB when using a filter resistor (RFILTER) of 4.7Ω. Applications requiring lower sample rates can tolerate a larger filter resistor for the same amount of full-scale error. LTC2302 LTC2306 RON 100Ω CIN 55pF VIN RFILTER CFILTER + – 23026 F02a Figure 2a. Analog Input Equivalent Circuit LTC2302 LTC2306 INPUT (CH0, CH1 IDC IN+, IN–) REQ 1/(fSMPL • CIN) VREF/2 23026 F02b Figure 2b. Analog Input Equivalent Circuit for Large Filter Capacitances 23026fb For more information www.linear.com/LTC2302 15 LTC2302/LTC2306 Applications Information Figures 3a and 3b show respective examples of input filtering for single-ended and differential inputs. For the single-ended case in Figure 3a, a 50Ω source resistor and a 2000pF capacitor to ground on the input will limit the input bandwidth to 1.6MHz. High quality capacitors and resistors should be used in the RC filter since these components can add distortion. NPO and silver mica type dielectric capacitors have excellent linearity. Carbon surface mount resistors can generate distortion from self heating and from damage that may occur during soldering. Metal film surface mount resistors are much less susceptible to both problems. Signal-to-Noise and Distortion Ratio (SINAD) The signal-to-noise and distortion ratio (SINAD) is the ratio between the RMS amplitude of the fundamental input frequency to the RMS amplitude of all other frequency components at the A/D output. The output is band-limited to frequencies from above DC and below half the sampling frequency. Figure 4 shows a typical SINAD of 72.8dB with a 500kHz sampling rate and a 1kHz input. A SNR of 73.2dB can be achieved with the LTC2302/LTC2306. FFT (fast Fourier transform) test techniques are used to test the ADC’s frequency response, distortion and noise at the rated throughput. By applying a low distortion sine wave and analyzing the digital output using an FFT algorithm, the ADC’s spectral content can be examined for frequencies outside the fundamental. 5V 0.1µF ANALOG INPUT 50Ω 150 200 250 Figure 4. 1kHz Sine Wave 8192 Point FFT Plot (LTC2306) LTC2306 10µF 50Ω DIFFERENTIAL ANALOG INPUTS 50Ω Total Harmonic Distortion (THD) 0.1µF VREF CH0, IN+ LTC2302 LTC2306 1000pF 10µF where V1 is the RMS amplitude of the fundamental fre‑ quency and V2 through VN are the amplitudes of the second through Nth harmonics. CH1, IN– 0.1µF Total Harmonic Distortion (THD) is the ratio of the RMS sum of all harmonics of the input signal to the fundamental itself. The out-of-band harmonics alias into the frequency band between DC and half the sampling frequency(fSMPL/2). THD is expressed as: V22 + V32 + V42 ... + VN2 THD = 20 log V1 1000pF 1000pF LT1790A-4.096 VOUT 100 23026 F04 Figure 3a. Optional RC Input Filtering for Single-Ended Input VIN 50 CH0, CH1 23026 F03a 0.1µF 0 2000pF LT1790A-4.096 5V SNR = 73.2dB SINAD = 72.8dB THD = –88.7dB FREQUENCY (kHz) VIN VOUT MAGNITUDE (dB) Dynamic Performance 0 –10 –20 –30 –40 –50 –60 –70 –80 –90 –100 –110 –120 –130 –140 VREF 23026 F03b Figure 3b. Optional RC Input Filtering for Differential Inputs 16 23026fb For more information www.linear.com/LTC2302 LTC2302/LTC2306 Applications Information Internal Conversion Clock The internal conversion clock is factory trimmed to achieve a typical conversion time (tCONV) of 1.3μs and a maximum conversion time of 1.6μs over the full operating temperature range. With a minimum acquisition time of 240ns, a throughput sampling rate of 500ksps is tested and guaranteed. Digital Interface The LTC2302/LTC2306 communicate via a standard 4­‑wire SPI compatible digital interface. The rising edge of CONVST initiates a conversion. After the conversion is finished, pull CONVST low to enable the serial output (SDO). The ADC then shifts out the digital data in 2’s complement format when operating in bipolar mode or in straight binary format when in unipolar mode, based on the setting of the UNI bit. For best performance, ensure that CONVST returns low within 40ns after the conversion starts (i.e., before the first bit decision) or after the conversion ends. If CONVST is low when the conversion ends, the MSB bit will appear at SDO at the end of the conversion and the ADC will remain powered up. Timing and Control The start of a conversion is triggered by the rising edge of CONVST. Once initiated, a new conversion cannot be restarted until the current conversion is complete. Figures 6 and 7 show the timing diagrams for two different examples of CONVST pulses. Example 1 (Figure 6) shows CONVST staying HIGH after the conversion ends. If CONVST is high after the tCONV period, the LTC2302/LTC2306 enter sleep mode (see Sleep Mode for more details). When CONVST returns low, the ADC wakes up and the most significant bit (MSB) of the output data sequence at SDO becomes valid after the serial data bus is enabled. All other data bits from SDO transition on the falling edge of each SCK pulse. Configuration data (DIN) is loaded into the LTC2302/LTC2306 at SDI, starting with the first SCK rising edge after CONVST returns low. The S/D bit is loaded on the first SCK rising edge. Example 2 (Figure 7) shows CONVST returning low be‑ fore the conversion ends. In this mode, the ADC and all internal circuitry remain powered up. When the conver‑ sion is complete, the MSB of the output data sequence at SDO becomes valid after the data bus is enabled. At this point(tCONV 1.3µs after the rising edge of CONVST), puls‑ ing SCK will shift data out at SDO and load configuration data (DIN) into the LTC2302/LTC2306 at SDI. The first SCK rising edge loads the S/D bit. SDO transitions on the falling edge of each SCK pulse. Figures 8 and 9 are the transfer characteristics for the bipolar and unipolar modes. Data is output at SDO in 2’s complement format for bipolar readings or in straight binary for unipolar readings. Sleep Mode The ADC enters sleep mode when CONVST is held high after the conversion is complete (tCONV). The supply current decreases to 7μA in sleep mode between conver‑ sions, thereby reducing the average power dissipation as the sample rate decreases. For example, the LTC2302/ LTC2306 draw an average of 14µA with a 1ksps sampling rate. The LTC2302/LTC2306 power down all circuitry when in sleep mode. Board Layout and Bypassing To obtain the best performance, a printed circuit board with a solid ground plane is required. Layout for the printed circuit board should ensure digital and analog signal lines are separated as much as possible. Care should be taken not to run any digital signal alongside an analog signal. All analog inputs should be shielded by GND. VREF and VDD should be bypassed to the ground plane as close to the pin as possible. Maintaining a low impedance path for the common return of these bypass capacitors is essential to the low noise operation of the ADC. These traces should be as wide as possible. See Figure 5 for a suggested layout. 23026fb For more information www.linear.com/LTC2302 17 LTC2302/LTC2306 Applications Information VDD, BYPASS 0.1µF||10µF, 0603 INPUT FILTER CAPACITORS SOLID GROUND PLANE OVDD, BYPASS 0.1µF, 0603 23026 F05 VREF, BYPASS 0.1µF||10µF 0603 Figure 5. Suggested Layout tWLCONVST tACQ CONVST tCONV SLEEP tCYC 1 2 3 4 5 6 7 8 9 10 11 12 SCK S/D BIT IS A DON’T CARE (X) FOR THE LTC2302 SDI S/D O/S UNI MSB SDO Hi-Z LSB B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0 Hi-Z 23026 F06 Figure 6. LTC2302/LTC2306 Timing with a Long CONVST Pulse 18 23026fb For more information www.linear.com/LTC2302 LTC2302/LTC2306 Applications Information tWHCONV tHCONVST tACQ CONVST tCYC tCONV 1 2 3 4 5 6 7 8 9 10 11 12 SCK S/D BIT IS A DON’T CARE (X) FOR THE LTC2302 SDI SDO S/D O/S Hi-Z UNI MSB LSB B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0 Hi-Z 23026 F07 011...111 111...111 BIPOLAR ZERO 011...110 111...110 000...001 OUTPUT CODE OUTPUT CODE (TWO’S COMPLEMENT) Figure 7. LTC2302/LTC2306 Timing with a Short CONVST Pulse 000...000 111...111 111...110 FS = 4.096V 1LSB = FS/2N 1LSB = 1mV 100...001 100...000 –FS/2 –1 0V 1 LSB LSB INPUT VOLTAGE (V) 100...001 100...000 011...111 UNIPOLAR ZERO 011...110 000...000 FS/2 – 1LSB 0V FS – 1LSB INPUT VOLTAGE (V) 23026 F08 Figure 8. LTC2302/LTC2306 Bipolar Transfer Characteristics (2’s Complement) FS = 4.096V 1LSB = FS/2N 1LSB = 1mV 000...001 20026 F09 Figure 9. LTC2302/LTC2306 Unipolar Transfer Characteristics (Straight Binary) 23026fb For more information www.linear.com/LTC2302 19 LTC2302/LTC2306 Package Description Please refer to http://www.linear.com/product/LTC2302#packaging for the most recent package drawings. DD Package 10-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1699 Rev C) 0.70 ±0.05 3.55 ±0.05 1.65 ±0.05 2.15 ±0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC 2.38 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 ±0.10 (4 SIDES) R = 0.125 TYP 6 0.40 ±0.10 10 1.65 ±0.10 (2 SIDES) PIN 1 NOTCH R = 0.20 OR 0.35 × 45° CHAMFER PIN 1 TOP MARK (SEE NOTE 6) 0.200 REF 0.75 ±0.05 0.00 – 0.05 5 1 (DD) DFN REV C 0310 0.25 ±0.05 0.50 BSC 2.38 ±0.10 (2 SIDES) BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2). CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 20 23026fb For more information www.linear.com/LTC2302 LTC2302/LTC2306 Revision History (Revision history begins at Rev B) REV DATE DESCRIPTION B 10/15 Changed REFCOMP to VREF PAGE NUMBER 3 23026fb Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa‑ tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. For more information www.linear.com/LTC2302 21 LTC2302/LTC2306 Typical Application Clock Squaring/Level Shifting Circuit Allows Testing with RF Sine Generator, Convert Re-Timing Flip-Flop Preserves Low Jitter Clock Timing 10µF 0.1µF 0.1µF VDD OVDD LTC2302 LTC2306 SDI CH0 (IN+) CH1 (IN–) ANALOG INPUT MUX + – 12-BIT 500ksps ADC SERIAL PORT SDO VCC SCK CONVST CONTROL LOGIC (FPGA, CPLD, DSP, ETC.) Q PRE D NL17SZ74 Q CLR CONVERT ENABLE VREF GND 0.1µF RF SIGNAL GENERATOR OR OTHER LOW JITTER SOURCE MASTER CLOCK •••••• CONVERT ENABLE •••••• CONVST •••••• 10µF VCC 0.1µF 1k 50Ω 1k MASTER CLOCK 23026 TA02 NC7SVU04P5X •••••• •••••• JITTER •••••• DATA TRANSFER Related Parts PART NUMBER DESCRIPTION COMMENTS LTC1417 14-Bit, 400ksps Serial ADC 20mW, Unipolar or Bipolar, Internal Reference, SSOP-16 Package LT1468/LT1469 Single/Dual 90MHz, 22V/µs, 16-Bit Accurate Op Amps Low Input Offset: 75µV/125µV LTC1609 16-Bit, 200ksps Serial ADC 65mW, Configurable Bipolar and Unipolar Input Ranges, 5V Supply LT1790 Micropower Low Dropout Reference 60µA Supply Current, 10ppm/°C, SOT-23 Package LTC1850/LTC1851 10-Bit/12-Bit, 8-channel, 1.25Msps ADCs Parallel Output, Programmable MUX and Sequencer, 5V Supply LTC1852/LTC1853 10-Bit/12-Bit, 8-channel, 400ksps ADCs Parallel Output, Programmable MUX and Sequencer, 3V or 5V Supply LTC1860/LTC1861 12-Bit, 1-/2-Channel 250ksps ADCs in MSOP 850µA at 250ksps, 2µA at 1ksps, SO-8 and MSOP Packages LTC1860L/LTC1861L 3V, 12-bit, 1-/2-Channel 150ksps ADCs 450µA at 150ksps, 10µA at 1ksps, SO-8 and MSOP Packages LTC1863/LTC1867 12-/16-Bit, 8-Channel 200ksps ADCs 6.5mW, Unipolar or Bipolar, Internal Reference, SSOP-16 Package LTC1863L/LTC1867L 3V, 12-/16-bit, 8-Channel 175ksps ADCs 2mW, Unipolar or Bipolar, Internal Reference, SSOP-16 Package LTC1864/LTC1865 16-Bit, 1-/2-Channel 250ksps ADCs in MSOP 850µA at 250ksps, 2µA at 1ksps, SO-8 and MSOP Packages LTC1864L/LTC1865L 3V, 16-Bit, 1-/2-Channel 150ksps ADCs in MSOP 450µA at 150ksps, 10µA at 1ksps, SO-8 and MSOP Packages LTC2308 12-Bit, 8-Channel 500ksps ADC 5V, Internal Reference, 4mm × 4mm QFN Packages 22 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 For more information www.linear.com/LTC2302 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/LTC2302 23026fb LT 1015 REV B • PRINTED IN USA  LINEAR TECHNOLOGY CORPORATION 2008
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