LTC2448 LINER [Linear Technology], LTC2448 Datasheet
LTC2448
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LTC2448 Summary of contents
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... REF GND 8-/16-Channel ∆Σ ADCs with Selectable Speed/Resolution DESCRIPTIO ® The LTC 2444/LTC2445/LTC2448/LTC2449 are 8-/16- channel (4-/8-differential) high speed 24-bit No Latency TM ADCs. They use a proprietary delta-sigma architec- ∆Σ ture enabling variable speed/resolution. Through a simple 4-wire serial interface, ten speed/resolution combinations 6 ...
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... Consult LTC Marketing for parts specified with wider operating temperature ranges Operating Temperature Range LTC2444C/LTC2445C/ + 0.3V) LTC2448C/LTC2449C .............................. 0°C to 70°C CC LTC2444I/LTC2445I/ + 0.3V) LTC2448I/LTC2449I ........................... – 40°C to 85° 0.3V) Storage Temperature Range ................. – 65°C to 125° 0.3V ORDER PART ...
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... Voltage – Voltage + Voltage – Voltage + – GND GND – REF = 5V, REF = GND 1.8MHz IN P-P LTC2444/LTC2445/ LTC2448/LTC2449 MIN TYP MAX ● 24 ● ppm ppm of V ● 2 ● ppm of V ● ppm of V 0.2 ppm of V ● ...
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... LTC2444/LTC2445/ LTC2448/LTC2449 U U DIGITAL I PUTS A D DIGITAL OUTPUTS operating temperature range, otherwise specifications are at T SYMBOL PARAMETER V High Level Input Voltage IH CS Low Level Input Voltage IL CS High Level Input Voltage IH SCK V Low Level Input Voltage IL SCK I Digital Input Current ...
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... SCK pin. A framing signal BUSY (Pin 2) goes low indicating data is being output. COM (Pin 7): The common negative input (IN single ended multiplexer configurations. The voltage on CH0-CH15 and COM pins can have any value between LTC2444/LTC2445/ LTC2448/LTC2449 MIN TYP MAX ● ● ...
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... LTC2445 No Connect/Channel Isolation Shield. May be left floating or tied to any voltage provide isolation for pairs of differential input channels. NC (Pins 24, 25, 26, 27): LTC2444/LTC2448 No Connect. These pins can either be tied to ground or left floating. MUXOUTP (Pin 24): LTC2445/LTC2449 Positive Multi- plexer Output. Used to drive the input to an external buffer/ amplifier ...
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... U APPLICATIO S I FOR ATIO CONVERTER OPERATION Converter Operation Cycle The LTC2444/LTC2445/LTC2448/LTC2449 are multi- channel, high speed, delta-sigma analog-to-digital con- verters with an easy to use 3- or 4-wire serial interface (see Figure 1). Their operation is made up of three states. The converter operating cycle begins with the conversion, followed by the low power sleep state and ends with the data output/input (see Figure 2) ...
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... POR is performed on the input channel + IN = CH0, IN Following the POR signal, the LTC2444/LTC2445/LTC2448/ LTC2449 start a normal conversion cycle and follow the succession of states described above. The first conver- sion result following POR is accurate within the specifica- tions of the device if the power supply voltage is restored within the operating range (4 ...
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... REF verter indicates the overrange or the underrange condition using distinct output codes. MUXOUT/ADCIN There are two differences between the LTC2444/LTC2448 and the LTC2445/LTC2449. The first is the RMS noise performance. For a given OSR, the LTC2445/LTC2449 noise level is approximately √2 times lower (0.5 effective bits)than that of the LTC2444/LTC2448 ...
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... For differential input voltages greater than REF +FS, the conversion result is clamped to the value corre- sponding to the +FS + 1LSB. For differential input voltages below –FS, the conversion result is clamped to the value corresponding to –FS – 1LSB. Table 2. LTC2444/LTC2445/LTC2448/LTC2449 Output Data Format Differential Input Voltage ≥ ...
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... For SGL = 0, two adjacent channels can be selected to form a differential input. For SGL = 1, one of 8 channels (LTC2444/LTC2445) or one of 16 channels (LTC2448/LTC2449) is selected as the positive input. The negative input is COM for all single ended operations. The remaining 4 bits (ODD, A2, A1, A0) determine which channel is selected ...
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... LTC2444/LTC2445/ LTC2448/LTC2449 U U APPLICATIO S I FOR ATIO Table 3. Channel Selection for the LTC2448/LTC2449 MUX ADDRESS ODD/ SGL SIGN – – ...
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... LTC2444/LTC2445/ LTC2448/LTC2449 COM + – – – – – IN – – – – IN – – – ...
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... LTC2444/LTC2445/ LTC2448/LTC2449 U U APPLICATIO S I FOR ATIO Table 5. LTC2444/LTC2445/LTC2448/LTC2449 Speed/Resolution Selection OSR3 OSR2 OSR1 OSR0 TWOX INTERNAL EXTERNAL ...
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... Prior to concluding the data out/in cycle, the analog multiplexer output is switched. This occurs at Table 6. LTC2444/LTC2445/LTC2448/LTC2449 Interface Timing Modes Configuration External SCK, Single Cycle Conversion External SCK, 2-Wire I/O ...
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... At the conclusion of the data cycle, CS may remain LOW and EOC monitored as an end-of-conversion interrupt. Alternatively, CS may be driven HIGH setting SDO to Hi-Z and BUSY monitored for the completion of a conversion. 2.7V TO 5.5V 1µF = EXTERNAL OSCILLATOR INTERNAL OSCILLATOR CC O LTC2448 REFERENCE REF SDI VOLTAGE 30 38 – REF SCK 0. ...
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... CH15 BUSY 1,4,5,6,31,32,33 7 COM GND DON'T CARE BIT 31 BIT 30 BIT 29 BIT 28 BIT 27 BIT 26 BIT 25 Hi-Z EOC “0” SIG MSB DATA OUTPUT CONVERSION LTC2444/LTC2445/ LTC2448/LTC2449 TEST EOC 6 DON'T CARE Hi-Z SLEEP CONVERSION sn2444589 2444589fs 2444 F06 17 ...
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... SCK. EOC can be latched on the first rising edge of SCK. On the 32nd falling edge of SCK, SDO and BUSY go HIGH (EOC = 1) indicating a new conversion has begun. 2.7V TO 5.5V 1µF = EXTERNAL OSCILLATOR INTERNAL OSCILLATOR LTC2448 REFERENCE REF SDI VOLTAGE 38 30 – 0. REF SCK ...
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... OSR3 BIT 29 BIT 28 BIT 27 BIT 26 BIT 25 BIT 24 BIT 23 BIT 22 BIT 21 SIG MSB DATA OUTPUT Figure 7. Internal Serial Clock, Single Cycle Operation LTC2444/LTC2445/ LTC2448/LTC2449 after the falling edge of CS EOCtest after EOC goes LOW ( LOW EOCtest EOCtest ...
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... If a new channel is being programmed, the rising edge of CS must come after the 14th falling edge of SCK in order to store the data input sequence. 2.7V TO 5.5V 1µ LTC2448 REFERENCE REF SDI VOLTAGE 30 38 – REF SCK 0 ...
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... EN SGL ODD OSR3 BIT 29 BIT 28 BIT 27 BIT 26 BIT 25 BIT 24 BIT 23 BIT 22 BIT 21 SIG MSB DATA OUTPUT Figure 9. Internal Serial Clock, Continuous Operation LTC2444/LTC2445/ LTC2448/LTC2449 OSR2 OSR1 OSR0 TWOX DON'T CARE BIT 20 BIT 19 BIT 0 LSB sn2444589 2444589fs ...
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... Normal Mode Rejection and Antialiasing One of the advantages delta-sigma ADCs offer over con- ventional ADCs is on-chip digital filtering. Combined with a large oversampling ratio, the LTC2444/LTC2445/ LTC2448/LTC2449 significantly simplify antialiasing filter requirements. The LTC2444/LTC2445/LTC2448/LTC2449’s speed/reso- lution is determined by the over sample ratio (OSR) of the on-chip digital filter ...
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... LTC1799, the output oscillator frequency is: grounded. While the The normal mode rejection characteristic shown in Figure 13 is achieved by applying the output of the LTC1799 (with R SET LTC2448/LTC2449 with SDI tied HIGH (OSR = 32768). 1.8MHz 2000000 1440 F13 Figure 13. LTC2444/LTC2445/LTC2448/LTC2449 Normal Mode Rejection (External Oscillator at 90kHz) ...
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... CURRENT Average Input Current The LTC2444/LTC2448 switch the input and reference to a 2pF capacitor at a frequency of 1.8MHz. A simplified equivalent circuit is shown in Figure 15. The sample capacitor for the LTC2445/LTC2449 is 4pF, and its aver- age input current is externally buffered from the input source ...
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... Effective noise bandwidth is a measure of how the ADC will reject wideband input noise up to the modu- lator sample rate. The example on the following page shows how the noise rejection of the LTC2444/LTC2445/ LTC2448/LTC2449 reduces the effective noise of an am- plifier driving its input. Maximum First Notch ...
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... U APPLICATIO S I FOR ATIO Example amplifier (e.g. LT1219) driving the input of an LTC2444/LTC2445/LTC2448/LTC2449 has wideband noise of 33nV/√Hz, band-limited to 1.8MHz, the total noise entering the ADC input is: 33nV/√Hz • √1.8MHz = 44.3µV. When the ADC digitizes the input, its digital filter filters out the wideband noise from the input signal ...
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... DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.20mm 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 LTC2444/LTC2445/ LTC2448/LTC2449 0.70 ± 0.05 PACKAGE OUTLINE 3.15 ± 0.10 0.435 ...
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... LTC2444/LTC2445/ LTC2448/LTC2449 U TYPICAL APPLICATIO CH0-CH15/ 17 COM RELATED PARTS PART NUMBER DESCRIPTION LT1025 Micropower Thermocouple Cold Junction Compensator LTC1043 Dual Precision Instrumentation Switched Capacitor Building Block LTC1050 Precision Chopper Stabilized Op Amp LT1236A-5 Precision Bandgap Reference, 5V LT1461 Micropower Series Reference, 2.5V LTC1592 Ultraprecise 16-Bit SoftSpan ...