LTC1285 LINER [Linear Technology], LTC1285 Datasheet
LTC1285
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LTC1285 Summary of contents
Page 1
... They are packaged in 8-pin SO packages and operate supplies. These 12-bit, switched- capacitor, successive approximation ADCs include sample-and-holds. The LTC1285 has a single differential analog input. The LTC1288 offers a software selectable 2-channel MUX. On-chip serial ports allow efficient data transfer to a wide range of microprocessors and microcontrollers over three wires ...
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... LTC1288 V = 2.7V CC LTC1285, f CLK LTC1288, f CLK V = 2.7V CC LTC1285 LTC1288 2.7V CC LTC1285, f CLK LTC1288, f CLK ORDER PART TOP VIEW NUMBER CLK LTC1285CS8 6 D OUT CS/SHDN 5 PART MARKING S8 PACKAGE 1285C = 175 C/W JA ORDER PART TOP VIEW NUMBER 8 ...
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... CONVERTER AND MULTIPLEXER CHARACTERISTICS PARAMETER Resolution (No Missing Codes) Integral Linearity Error Differential Linearity Error Offset Error Gain Error Analog Input Range REF Input Range (LTC1285) (Notes 7, 8, and 9) Analog Input Leakage Current (Note 10) U DIGITAL AND DC ELECTRICAL CHARACTERISTICS SYMBOL PARAMETER V High Level Input Voltage ...
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... CLK reference and analog input range are greater than 6.05V, the output code will not be guaranteed to be correct. Note 8: The supply voltage range for the LTC1285 and the LTC1288 is from 2.7V to 6V. Note 9: Recommended operating conditions Note 10: Channel leakage current is measured after the channel selection. ...
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... A – 2. 120kHz CLK – 7.5kHz SMPL – 7 – 6 – 5 – 4 – 3 – 2 – 2.8 1.0 1.2 1.4 1.6 1.8 2.0 REFERENCE VOLTAGE ( 25° 2. 120kHz CLK 10 100 INPUT FREQUENCY (kHz) LTC1285/88 • TPC12 2.5 3.0 LTC1285/88 • TPC06 2.2 2.4 2.6 2.8 LTC1285/88 • TPC09 5 ...
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... LTC1285/88 • TPC17 Sample-and-Hold Acquisition Time vs Source Resistance 10000 T = 25° 2. 2.5V REF 1000 + R SOURCE V IN 100 100 1000 SOURCE RESISTANCE ( ) LTC1285/88 • TPC20 Attenuation vs Input Frequency 25° 2. 2.5V REF SMPL SMPL(MAX) 100 – ...
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... Negative Analog Input. GND (Pin 4): Analog Ground. GND should be tied directly to an analog ground plane. CS/SHDN (Pin 5): Chip Select Input. A logic low on this input enables the LTC1285. A logic high on this input disables and powers down the LTC1285. D (Pin 6): Digital Data Output. The A/D conversion OUT result is shifted out of this output ...
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... LTC1285/88 • TC03 CLK SERIAL PORT D OUT SAR LTC1285/88 • BD Rise and Fall Times, t OUT t r Load Circuit for t and t dis en TEST POINT V t WAVEFORM dis 3k D OUT t WAVEFORM 1 dis 100pF , LTC1285/88 • TC02 en LTC1285/88 • TC04 ...
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... THAT THE OUTPUT IS LOW UNLESS DISABLED BY THE OUTPUT CONTROL. LTC1288 CLK D OUT dis LTC1285 90% CLK t dis 10% D OUT LTC1285/88 • TC05 Voltage Waveforms for t en START LTC1285/LTC1288 Voltage Waveforms for B11 LTC1285/88 • TC07 B11 LTC1285/88 • TC06 9 ...
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... W U basic design, the LTC1285 and LTC1288 differ in some respects. The LTC1285 has a differential input and has an external reference input pin. It can measure signals float- ing common-mode voltage and can operate with reduced spans to 1.5V. Reducing the spans allows it to achieve 366 V resolution. The LTC1288 has a two-chan- nel input multiplexer and can convert either channel with respect to ground or the difference between the two ...
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... Figure 2. LTC1288 Operating Sequence Example: Differential Inputs ( CYC DON’T CARE CONV t CYC DON’T CARE B0 CONV DATA LTC1285/LTC1288 POWER DOWN B10 B11 * t DATA POWER DOWN HI-Z + – HI-Z LTC1285/88 • F02 11 ...
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... LTC1285 operating sequence. After CS falls the second CLK pulse enables D OUT A/D conversion result is output on the D CS high resets the LTC1285 for the next data exchange. The LTC1288 first receives input data and then transmits back the A/D conversion result (half duplex). Because of the half duplex operation, D ...
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... U U APPLICATION INFORMATION Transfer Curve The LTC1285/LTC1288 are permanently configured for unipolar only. The input span and code assignment for this conversion type are shown in the following figures. Transfer Curve • ...
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... The currents must be evaluated and the troublesome ones minimized. and IN OPERATING ON OTHER THAN 3V SUPPLIES Both the LTC1285 and the LTC1288 operate from a 2. supply. To operate the LTC1285/LTC1288 on other than 3V supplies a few things must be kept in mind. Input Logic Levels The input logic levels of CS, CLK and D meet TTL supply ...
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... REF CC DIFFERENTIAL INPUTS +IN CLK COMMON-MODE RANGE –IN D OUT GND CS LTC1285 Figure 6. Interfacing a 3V Powered LTC1285 System CS CLK OUT "+" INPUT "–" INPUT W U BOARD LAYOUT CONSIDERATIONS Grounding and Bypassing The LTC1285/LTC1288 are easy to use if some care is taken ...
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... W U “+” Input Settling The input capacitor of the LTC1285 is switched onto “+” input during the t the input signal within that time. However, the input capacitor of the LTC1288 is switched onto “+” input during the sample phase (t sample phase is 1 1/2 CLK cycles before conversion starts. The voltage on the “ ...
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... Current vs Temperature 20pF IN REFERENCE INPUTS The reference input of the LTC1285 is effectively a 50k LTC1285/88 • F08 resistor from the time CS goes low to the end of the conversion. The reference input becomes a high impedence node at any other time (see Figure 10). Since the voltage on the reference input defines the voltage span of the A/D ...
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... Conversion speed (CLK frequency) Offset with Reduced V REF The offset of the LTC1285 has a larger effect on the output code. When the ADC is operated with reduced reference voltage. The offset (which is typically a fixed voltage) becomes a larger fraction of an LSB as the size of the LSB is reduced ...
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... ADC and is directly related to S/(N+D) by the equation: ENOB = [S/( – 1.76]/6.02 where S/( expressed in dB. At the maximum sampling rate of 7.5kHz with a 2.7V supply, the LTC1285 maintains above 10.7 ENOBs at 10kHz input frequency. Above 10kHz the ENOBs gradually decline, as shown in Figure 12, due to increasing second harmonic distortion. ...
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... Table 1 MPU without a dedicated serial port is used, then the MPU's parallel port lines can be programmed to form the serial link to the LTC1285/LTC1288. Included here is one serial interface example and one example showing a parallel port programmed to form the serial interface. ...
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... LOAD DUMMY INTO ACC A FROM $52 $102A LOAD DUMMY DIN INTO SPI, START SCK $1029 CHECK SPI STATUS REG WAIT3 CHECK IF TRANSFER IS DONE $08,X#$01 DO GOES HIGH (CS GOES HIGH) $102A LOAD LTC1288 LSBs IN ACC $63 STORE LSBs IN $63 LOOP START NEXT CONVERSION LTC1285/88 • TA03 21 ...
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... SETB P1.3 SCLK goes high CLR P1.3 SCLK goes low DJNZ R4, LOOP 3 Next bit MOV R4, #04 Load counter RRC A Rotate right into Acc. DJNZ R4, LOOP 4 Next Rotate MOV R3, A Store LSBs in R3 SETB P1.4 CS goes high BACK TO 8051 P1.2 LTC1285/88 • TA07 B0 ...
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... A from the 2.7V supply at f outputs the data. The 62 A from the battery. The 12-bits of resolution of the LTC1285 are positioned over the desired range 16V. This is easily accomplished by using the ADC’s differential inputs. Tying the –input to the reference gives an ADC input span of V resistor divider then scales the input voltage for 8V to 16V ...
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... LTC1285/LTC1288 PACKAGE DESCRIPTION 0.300 – 0.325 (7.620 – 8.255) 0.065 (1.651) 0.009 – 0.015 TYP (0.229 – 0.381) 0.005 (0.127) +0.025 0.325 –0.015 +0.635 8.255 –0.381 0.100 0.010 (2.540 0.254) *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm) 0.010 – ...