Datasheet LTC2321-12 (Analog Devices) - 9

LTC2321-12
PIN FUNCTIONS VDD (Pins 1, 8):
Power Supply. Bypass VDD to GND with on SDO1+. The logic level is determined by OVDD. Do a 10µF ceramic and a 0.1µF ceramic close to the part. The not connect SDO1–. In LVDS mode, the result is output VDD pins should be shorted together and driven from the differentially on SDO1+ and SDO1–. These pins must be same supply. differentially terminated by an external 100Ω resistor at
A
the receiver (FPGA).
IN2+, AIN2– (Pins 2, 3):
Analog Differential Input Pins. Full-scale range (AIN2+ – AIN2–) is ±REFOUT2 voltage.
CLKOUT+, CLKOUT– (Pins 17, 18):
Serial Data Clock These pins can be driven from VDD to GND. Output. CLKOUT provides a skew-matched clock to latch
GND (Pins 4, 5, 10, 29):
Ground. These pins and exposed the SDO output at the receiver. In CMOS mode, the skew- pad (Pin 29) must be tied directly to a solid ground plane. matched clock is output on CLKOUT+. The logic level is determined by OVDD. Do not connect CLKOUT–. For
AIN1–, AIN1+ (Pins 6, 7):
Analog Differential Input Pins. low throughput applications using SCK to latch the SDO Full-scale range (AIN1+ – AIN1–) is ±REFOUT1 voltage. output, CLKOUT+ can be disabled by tying CLKOUT– to These pins can be driven from VDD to GND. OVDD. In LVDS mode, the skew-matched clock is output
CNV (Pin 9):
Conversion Start Input. A falling edge on CNV differentially on CLKOUT+ and CLKOUT–. These pins must puts the internal sample-and-hold into the hold mode and be differentially terminated by an external 100Ω resistor starts a conversion cycle. CNV must be driven by a low at the receiver (FPGA). jitter clock as shown in the Typical Application circuit on
SDO2+, SDO2– (Pins 19, 20):
Channel 2 Serial Data Out- the back page. The CNV pin is unaffected by the CMOS/ put. The conversion result is shifted MSB first on each LVDS pin. falling edge of SCK. In CMOS mode, the result is output
REFRTN1 (Pin 11):
Reference Buffer 1 Output Return. on SDO2+. The logic level is determined by OVDD. Do Bypass REFRTN1 to REFOUT1. Do not tie the REFRTN1 not connect SDO2–. In LVDS mode, the result is output pin to the ground plane. differentially on SDO2+ and SDO2–. These pins must be differentially terminated by an external 100Ω resistor at
REFOUT1 (Pin 12):
Reference Buffer 1 Output. An onboard the receiver (FPGA). buffer nominally outputs 4.096V to this pin. This pin is re- ferred to REFRTN1 and should be decoupled closely to the
SCK+, SCK– (Pins 21, 22):
Serial Data Clock Input. The pin (no vias) with a 0.1µF (X7R, 0402 size) capacitor and falling edge of this clock shifts the conversion result MSB a 10μF (X5R, 0805 size) ceramic capacitor in parallel. The first onto the SDO pins. In CMOS mode, drive SCK+ with internal buffer driving this pin may be disabled by ground- a single-ended clock. The logic level is determined by ing the REFINT pin. If the buffer is disabled, an external OVDD. Do not connect SCK–. In LVDS mode, drive SCK+ reference may drive this pin in the range of 1.25V to 5V. and SCK– with a differential clock. These pins must be differentially terminated by an external 100Ω resistor at
VBYP1 (Pin 13):
Bypass this internally supplied pin to the receiver (ADC). ground with a 1µF ceramic capacitor. The nominal output voltage on this pin is 1.6V.
OGND (Pin 23):
I/O Ground. This ground must be tied to the ground plane at a single point. OV
OV
DD is bypassed to this pin.
DD (Pin 14):
I/O Interface Digital Power. The range of OV
VBYP2 (Pin 24):
Bypass this internally supplied pin to DD is 1.71V to 2.5V. This supply is nominally set to the same supply as the host interface (CMOS: 1.8V or 2.5V, ground with a 1µF ceramic capacitor. The nominal output LVDS: 2.5V). Bypass OV voltage on this pin is 1.6V DD to OGND with a 0.1μF capacitor.
SDO1+, SDO1– (Pins 15, 16):
Channel 1 Serial Data Out-
CMOS/LVDS (Pin 25):
I/O Mode Select. Ground this pin put. The conversion result is shifted MSB first on each to enable CMOS mode, tie to OVDD to enable LVDS mode. falling edge of SCK. In CMOS mode, the result is output Float this pin to enable low power LVDS mode. 232112fb For more information www.linear.com/LTC2321-12 9 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Converter Characteristics Dynamic Accuracy Internal Reference Characteristics Digital Inputs And Digital Outputs Power Requirements ADC Timing Characteristics Typical Performance Characteristics Pin Functions Functional Block Diagram Timing Diagram Applications Information Package Description Related Parts