Datasheet LTC6409 (Analog Devices) - 9

LTC6409
BLOCK DIAGRAM
2 1 +IN –OUT 3 V– 10 SHDN V+ V+ V– 200k + 5 V+ 9 VOCM 50k – V+ V– V– 4 V+ V– 8 V+ V– –IN +OUT 6 7 6409 BD
APPLICATIONS INFORMATION Functional Description
Moreover, the input pins, as well as VOCM and SHDN The LTC6409 is a small outline, wideband, high speed, pins, have clamping diodes to either power supply. If low noise, and low distortion fully-differential amplifier these pins are driven to voltages which exceed either with accurate output phase balancing. The amplifier is supply, the current should be limited to 10mA to prevent optimized to drive low voltage, single-supply, differential damage to the IC. input analog-to-digital converters (ADCs). The LTC6409
SHDN Pin
input common mode range includes ground, which makes it ideal to DC-couple and convert ground-referenced, The SHDN pin is a CMOS logic input with a 150k inter- single-ended signals into differential signals that are ref- nal pull-up resistor. If the pin is driven low, the LTC6409 erenced to the user-supplied output common mode volt- powers down. If the pin is left unconnected or driven age. This is ideal for driving these differential ADCs. The high, the part is in normal active operation. Some care balanced differential nature of the amplifier also provides should be taken to control leakage currents at this pin to even-order harmonic distortion cancellation, and low prevent inadvertently putting the LTC6409 into shutdown. susceptibility to common mode noise (like power sup- The turn-on and turn-off time between the shutdown and ply noise). The LTC6409 can operate with a single-ended active states is typically less than 200ns. input and differential output, or with a differential input and differential output.
General Amplifier Applications
The outputs of the LTC6409 are capable of swinging from In Figure 1, the gain to VOUTDIFF from VINP and VINM is close-to-ground to 1V below V+. They can source or sink given by: up to approximately 70mA of current. Load capacitances should be decoupled with at least 10Ω of series resistance VOUTDIFF = V+OUT – V–OUT ≈ RF • (V ) (1) R INP – VINM from each output. I Note from Equation (1), the differential output voltage
Input Pin Protection
(V+OUT – V–OUT) is completely independent of input and The LTC6409 input stage is protected against differential output common mode voltages, or the voltage at the com- input voltages which exceed 1.4V by two pairs of series mon mode pin. This makes the LTC6409 ideally suited diodes connected back to back between +IN and –IN. for pre-amplification, level shifting and conversion of 6409fb For more information www.linear.com/LTC6409 9 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Applications Information Typical Applications Package Description Revision History Typical Applications Related Parts Features Applications Typical Application Description Absolute Maximum Ratings Order Information Electrical Characteristics Pin Configuration Typical Performance Characteristics Pin Functions Block Diagram Applications Information Typical Applications Package Description Revision History Typical Applications Related Parts