Datasheet LTC2280 (Analog Devices) - 8

LTC2280
U U U PI FU CTIO S A + INA (Pin 1):
Channel A Positive Differential Analog and a ±1V input range. An external reference greater than Input. 0.5V and less than 1V applied to SENSEB selects an input range of ±V
A –
SENSEB. ±1V is the largest valid input range.
INA (Pin 2):
Channel A Negative Differential Analog Input.
VCMB (Pin 20):
Channel B 1.5V Output and Input Common Mode Bias. Bypass to ground with 2.2µF ceramic chip
REFHA (Pins 3, 4):
Channel A High Reference. Short capacitor. Do not connect to V together and bypass to Pins 5, 6 with a 0.1µF ceramic chip CMA. capacitor as close to the pin as possible. Also bypass to
MUX (Pin 21):
Digital Output Multiplexer Control. If MUX Pins 5, 6 with an additional 2.2µF ceramic chip capacitor is High, Channel A comes out on DA0-DA9, OFA; Channel B and to ground with a 1µF ceramic chip capacitor. comes out on DB0-DB9, OFB. If MUX is Low, the output busses are swapped and Channel A comes out on DB0-
REFLA (Pins 5, 6):
Channel A Low Reference. Short DB9, OFB; Channel B comes out on DA0-DA9, OFA. To together and bypass to Pins 3, 4 with a 0.1µF ceramic chip multiplex both channels onto a single output bus, connect capacitor as close to the pin as possible. Also bypass to MUX, CLKA and CLKB together. (This is not recommended Pins 3, 4 with an additional 2.2µF ceramic chip capacitor at clock frequencies above 80Msps.) and to ground with a 1µF ceramic chip capacitor.
SHDNB (Pin 22):
Channel B Shutdown Mode Selection
VDD (Pins 7, 10, 18, 63):
Analog 3V Supply. Bypass to Pin. Connecting SHDNB to GND and OEB to GND results GND with 0.1µF ceramic chip capacitors. in normal operation with the outputs enabled. Connecting
CLKA (Pin 8):
Channel A Clock Input. The input sample SHDNB to GND and OEB to VDD results in normal opera- starts on the positive edge. tion with the outputs at high impedance. Connecting
CLKB (Pin 9):
Channel B Clock Input. The input sample SHDNB to VDD and OEB to GND results in nap mode with starts on the positive edge. the outputs at high impedance. Connecting SHDNB to VDD and OEB to VDD results in sleep mode with the outputs at
REFLB (Pins 11, 12):
Channel B Low Reference. Short high impedance. together and bypass to Pins 13, 14 with a 0.1µF ceramic chip capacitor as close to the pin as possible. Also bypass
OEB (Pin 23):
Channel B Output Enable Pin. Refer to to Pins 13, 14 with an additional 2.2µF ceramic chip ca- SHDNB pin function. pacitor and to ground with a 1µF ceramic chip capacitor.
NC (Pins 24 to 27, 41 to 44):
Do Not Connect These Pins.
REFHB (Pins 13, 14):
Channel B High Reference. Short
DB0 – DB9 (Pins 28 to 30, 33 to 39):
Channel B Digital together and bypass to Pins 11, 12 with a 0.1µF ceramic Outputs. DB9 is the MSB. chip capacitor as close to the pin as possible. Also bypass
OGND (Pins 31, 50):
Output Driver Ground. to Pins 11, 12 with an additional 2.2µF ceramic chip ca- pacitor and to ground with a 1µF ceramic chip capacitor.
OVDD (Pins 32, 49):
Positive Supply for the Output Driv- ers. Bypass to ground with 0.1µF ceramic chip capacitor.
A – INB (Pin 15):
Channel B Negative Differential Analog Input.
OFB (Pin 40):
Channel B Overflow/Underflow Output. High when an overflow or underflow has occurred.
A + INB (Pin 16):
Channel B Positive Differential Analog Input.
DA0 – DA9 (Pins 45 to 48, 51 to 56):
Channel A Digital Outputs. DA9 is the MSB.
GND (Pins 17, 64):
ADC Power Ground.
OFA (Pin 57):
Channel A Overflow/Underflow Output.
SENSEB (Pin 19):
Channel B Reference Programming Pin. High when an overflow or underflow has occurred. Connecting SENSEB to VCMB selects the internal reference and a ±0.5V input range. VDD selects the internal reference
OEA (Pin 58):
Channel A Output Enable Pin. Refer to SHDNA pin function. 2280fa 8