Datasheet LT1994 (Analog Devices) - 9
| Manufacturer | Analog Devices |
| Description | Low Noise, Low Distortion Fully Differential Input/Output Amplifier/Driver |
| Pages / Page | 20 / 9 — PIN FUNCTIONS. IN+, IN– (Pins 1, 8):. V+, V– (Pins 3, 6):. VOCM (Pin 2):. … |
| File Format / Size | PDF / 232 Kb |
| Document Language | English |
PIN FUNCTIONS. IN+, IN– (Pins 1, 8):. V+, V– (Pins 3, 6):. VOCM (Pin 2):. OUT+, OUT– (Pins 4, 5):. SHDN. (Pin 7):
Model Line for this Datasheet
Text Version of Document
LT1994
PIN FUNCTIONS IN+, IN– (Pins 1, 8):
Noninverting and Inverting Input
V+, V– (Pins 3, 6):
Power Supply Pins. For single-supply Pins of the Amplifi er, Respectively. For best performance, applications (Pin 6 grounded) it is recommended that it is highly recommended that stray capacitance be high quality 1μF and 0.1μF ceramic bypass capacitors be kept to an absolute minimum by keeping printed circuit placed from the positive supply pin (Pin 3) to the negative connections as short as possible, and if necessary, strip- supply pin (Pin 6) with minimal routing. Pin 6 should be ping back nearby surrounding ground plane away from directly tied to a low impedance ground plane. For dual these pins. power supplies, it is recommended that high quality, 0.1μF ceramic capacitors are used to bypass Pin 3 to ground
VOCM (Pin 2):
Output Common Mode Reference Voltage. and Pin 6 to ground. It is also highly recommended that The VOCM pin is the midpoint of an internal resistive volt- high quality 1μF and 0.1μF ceramic bypass capacitors be age divider between the supplies, developing a (default) placed across the power supply pins (Pins 3 and 6) with mid-supply voltage potential to maximize output signal minimal routing. swing. VOCM has a Thevenin equivalent resistance of approximately 40k and can be overdriven by an external
OUT+, OUT– (Pins 4, 5):
Output Pins. Each pin can drive voltage reference. The voltage on VOCM sets the output approximately 100Ω to ground with a short-circuit current common mode voltage level (which is defi ned as the av- limit of up to ±85mA. Each amplifi er output is designed erage of the voltages on the OUT+ and OUT– pins). VOCM to drive a load capacitance of 25pF. This basically means should be bypassed with a high quality ceramic bypass the amplifi er can drive 25pF from each output to ground capacitor of at least 0.1μF (unless connected directly to or 12.5pF differentially. Larger capacitive loads should be a low impedance, low noise ground plane) to minimize decoupled with at least 25Ω resistors from each output. common mode noise from being converted to differen-
SHDN (Pin 7):
When Pin 7 (SHDN) is fl oating or when tial noise by impedance mismatches both externally and Pin 7 is directly tied to V+, the LT1994 is in the normal internally to the IC. operating mode. When Pin 7 is pulled a minimum of 2.1V below V+, the LT1994 enters into a low power shutdown state. Refer to the SHDN pin section under Applications Information for a description of the LT1994 output imped- ance in the shutdown state. 1994fb 9
PIN FUNCTIONS IN+, IN– (Pins 1, 8):
Noninverting and Inverting Input
V+, V– (Pins 3, 6):
Power Supply Pins. For single-supply Pins of the Amplifi er, Respectively. For best performance, applications (Pin 6 grounded) it is recommended that it is highly recommended that stray capacitance be high quality 1μF and 0.1μF ceramic bypass capacitors be kept to an absolute minimum by keeping printed circuit placed from the positive supply pin (Pin 3) to the negative connections as short as possible, and if necessary, strip- supply pin (Pin 6) with minimal routing. Pin 6 should be ping back nearby surrounding ground plane away from directly tied to a low impedance ground plane. For dual these pins. power supplies, it is recommended that high quality, 0.1μF ceramic capacitors are used to bypass Pin 3 to ground
VOCM (Pin 2):
Output Common Mode Reference Voltage. and Pin 6 to ground. It is also highly recommended that The VOCM pin is the midpoint of an internal resistive volt- high quality 1μF and 0.1μF ceramic bypass capacitors be age divider between the supplies, developing a (default) placed across the power supply pins (Pins 3 and 6) with mid-supply voltage potential to maximize output signal minimal routing. swing. VOCM has a Thevenin equivalent resistance of approximately 40k and can be overdriven by an external
OUT+, OUT– (Pins 4, 5):
Output Pins. Each pin can drive voltage reference. The voltage on VOCM sets the output approximately 100Ω to ground with a short-circuit current common mode voltage level (which is defi ned as the av- limit of up to ±85mA. Each amplifi er output is designed erage of the voltages on the OUT+ and OUT– pins). VOCM to drive a load capacitance of 25pF. This basically means should be bypassed with a high quality ceramic bypass the amplifi er can drive 25pF from each output to ground capacitor of at least 0.1μF (unless connected directly to or 12.5pF differentially. Larger capacitive loads should be a low impedance, low noise ground plane) to minimize decoupled with at least 25Ω resistors from each output. common mode noise from being converted to differen-
SHDN (Pin 7):
When Pin 7 (SHDN) is fl oating or when tial noise by impedance mismatches both externally and Pin 7 is directly tied to V+, the LT1994 is in the normal internally to the IC. operating mode. When Pin 7 is pulled a minimum of 2.1V below V+, the LT1994 enters into a low power shutdown state. Refer to the SHDN pin section under Applications Information for a description of the LT1994 output imped- ance in the shutdown state. 1994fb 9
