Datasheet LT1398, LT1399, LT1399HV (Analog Devices) - 9

LT1398/LT1399/LT1399HV
U U U PIN FUNCTIONS LT1398 LT1399, LT1399HV – IN A (Pin 1):
Inverting Input of A Channel Amplifier.
– IN R (Pin 1):
Inverting Input of R Channel Amplifier.
+ IN A (Pin 2):
Noninverting Input of A Channel Amplifier.
+ IN R (Pin 2):
Noninverting Input of R Channel Amplifier.
GND (Pins 3, 4, 5, 6):
Ground. Not connected internally.
GND (Pin 3):
Ground. Not connected internally.
+ IN B (Pin 7):
Noninverting Input of B Channel Amplifier.
– IN G (Pin 4):
Inverting Input of G Channel Amplifier.
– IN B (Pin 8):
Inverting Input of B Channel Amplifier.
+ IN G (Pin 5):
Noninverting Input of G Channel Amplifier.
EN B (Pin 9):
B Channel Enable Pin. Logic low to enable.
GND (Pin 6):
Ground. Not connected internally.
OUT B (Pin 10):
B Channel Output.
+ IN B (Pin 7):
Noninverting Input of B Channel Amplifier.
V – (Pin 11):
Negative Supply Voltage, Usually – 5V.
– IN B (Pin 8):
Inverting Input of B Channel Amplifier.
GND (Pins 12, 13):
Ground. Not connected internally.
EN B (Pin 9):
B Channel Enable Pin. Logic low to enable.
V + (Pin 14):
Positive Supply Voltage, Usually 5V.
OUT B (Pin 10):
B Channel Output.
OUT A (Pin 15):
A Channel Output.
V – (Pin 11):
Negative Supply Voltage, Usually – 5V.
EN A (Pin 16):
A Channel Enable Pin. Logic low to enable.
OUT G (Pin 12):
G Channel Output.
EN G (Pin 13):
G Channel Enable Pin. Logic low to enable.
V + (Pin 14):
Positive Supply Voltage, Usually 5V.
OUT R (Pin 15):
R Channel Output.
EN R (Pin 16):
R Channel Enable Pin. Logic low to enable.
O U U W U APPLICATI S I FOR ATIO Feedback Resistor Selection
Take care to minimize the stray capacitance between the output and the inverting input. Capacitance on the invert- The small-signal bandwidth of the LT1398/LT1399/ ing input to ground will cause peaking in the frequency LT1399HV is set by the external feedback resistors and the response (and overshoot in the transient response). internal junction capacitors. As a result, the bandwidth is a function of the supply voltage, the value of the feedback
Capacitive Loads
resistor, the closed-loop gain and the load resistor. The The LT1398/LT1399/LT1399HV can drive many capaci- LT1398/LT1399 have been optimized for ±5V supply tive loads directly when the proper value of feedback operation and have a – 3dB bandwidth of 300MHz at a gain resistor is used. The required value for the feedback of 2. The LT1399HV provides performance similar to the resistor will increase as load capacitance increases and as LT1399. Please refer to the resistor selection guide in the closed-loop gain decreases. Alternatively, a small resistor Typical AC Performance table. (5Ω to 35Ω) can be put in series with the output to isolate
Capacitance on the Inverting Input
the capacitive load from the amplifier output. This has the advantage that the amplifier bandwidth is only reduced Current feedback amplifiers require resistive feedback when the capacitive load is present. The disadvantage is from the output to the inverting input for stable operation. that the gain is a function of the load resistance. sn13989 13989fas 9