LTC1272 PIN FUNCTIONSAIN (Pin 1): Analog Input, 0V to 5V Unipolar Input. HBEN (Pin 19): High Byte Enable Input. This pin is used V to multiplex the internal 12-bit conversion result into the REF (Pin 2): 2.42V Reference Output. When plugging into an AD7572 socket, reverse the reference bypass capacitor lower bit outputs (D7 to D0/8). See table below. HBEN polarity and short the 10Ω series resistor. also disables conversion starts when HIGH. AGND (Pin 3): Analog Ground. RD (Pin 20): Read Input. This active low signal starts a conversion when CS and HBEN are low. RD also enables D11 to D4 (Pins 4-11): Three-State Data Outputs. the output drivers when CS is low. DGND (Pin 12): Digital Ground. CS (Pin 21): The Chip Select Input must be low for the D3/11 to D0/8 (Pins 13-16): Three-State Data Outputs. ADC to recognize RD and HBEN inputs. CLK IN (Pin 17): Clock Input. An external TTL/CMOS BUSY (Pin 22): The BUSY Output is low when a conver- compatible clock may be applied to this pin or a crystal sion is in progress. can be connected between CLK IN and CLK OUT. NC (Pin 23): Not Connected Internally. The LTC1272 does CLK OUT (Pin 18): Clock Output. An inverted CLK IN signal not require negative supply. This pin can accommodate appears at this pin. the –15V required by the AD7572 without problems. VDD (Pin 24): Positive Supply, 5V. Data Bus Output, CS and RD = LOWPin 4Pin 5Pin 6Pin 7Pin 8Pin 9Pin 10Pin 11Pin 13Pin 14Pin 15Pin 16 MNEMONIC* D11 D10 D9 D8 D7 D6 D5 D4 D3/11 D2/10 D1/9 D0/8 HBEN = LOW DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 HBEN = HIGH DB11 DB10 DB9 DB8 LOW LOW LOW LOW DB11 DB10 DB9 DB8 * D11...D0/8 are the ADC data output pins. DB11...DB0 are the 12-bit conversion results, DB11 is the MSB. TYPICAL PERFORMANCE CHARACTERISTICSIntegral Nonlinearity 1.0 VDD = 5V fCLK = 4MHz 0.5 0 INL ERROR (LSBs) –0.5 –1.0 0 512 1024 1536 2048 2560 3072 3584 4096 CODE LTC1272 • G01 1272fc 6 For more information www.linear.com/1272 Document Outline FEATURES APPLICATIONS DESCRIPTION TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION CONVERTER CHARACTERISTICS INTERNAL REFERENCE CHARACTERISTICS DIGITAL AND DC ELECTRICAL CHARACTERISTICS DYNAMIC ACCURACY ANALOG INPUT TIMING CHARACTERISTICS PIN FUNCTIONS TYPICAL PERFORMANCE CHARACTERISTICS APPLICATIONS INFORMATION REVISION HISTORY PACKAGE DESCRIPTION