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LT1398/LT1399/LT1399HV

LT1399, LT1399HV

– IN R (Pin 1): Inverting Input of R Channel Amplifier.

+ IN R (Pin 2): Noninverting Input of R Channel Amplifier.

GND (Pin 3): Ground. Not connected internally.

– IN G (Pin 4): Inverting Input of G Channel Amplifier.

+ IN G (Pin 5): Noninverting Input of G Channel Amplifier.

GND (Pin 6): Ground. Not connected internally.

+ IN B (Pin 7): Noninverting Input of B Channel Amplifier.

– IN B (Pin 8): Inverting Input of B Channel Amplifier.

EN B (Pin 9): B Channel Enable Pin. Logic low to enable.

OUT B (Pin 10): B Channel Output.

OUT G (Pin 12): G Channel Output.

EN G (Pin 13): G Channel Enable Pin. Logic low to enable.

OUT R (Pin 15): R Channel Output.

EN R (Pin 16): R Channel Enable Pin. Logic low to enable.

Take care to minimize the stray capacitance between the

output and the inverting input. Capacitance on the invert-

ing input to ground will cause peaking in the frequency

response (and overshoot in the transient response).

Capacitive Loads

The LT1398/LT1399/LT1399HV can drive many capaci-

tive loads directly when the proper value of feedback

resistor is used. The required value for the feedback

resistor will increase as load capacitance increases and as

closed-loop gain decreases. Alternatively, a small resistor

(5

Ω to 35Ω) can be put in series with the output to isolate

the capacitive load from the amplifier output. This has the

advantage that the amplifier bandwidth is only reduced

when the capacitive load is present. The disadvantage is

that the gain is a function of the load resistance.

S

APPLICATI

I FOR ATIO

Feedback Resistor Selection

The small-signal bandwidth of the LT1398/LT1399/

LT1399HV is set by the external feedback resistors and the

internal junction capacitors. As a result, the bandwidth is

a function of the supply voltage, the value of the feedback

resistor, the closed-loop gain and the load resistor. The

LT1398/LT1399 have been optimized for

±5V supply

operation and have a – 3dB bandwidth of 300MHz at a gain

of 2. The LT1399HV provides performance similar to the

LT1399. Please refer to the resistor selection guide in the

Typical AC Performance table.

Capacitance on the Inverting Input

Current feedback amplifiers require resistive feedback

from the output to the inverting input for stable operation.

LT1398

– IN A (Pin 1): Inverting Input of A Channel Amplifier.

+ IN A (Pin 2): Noninverting Input of A Channel Amplifier.

GND (Pins 3, 4, 5, 6): Ground. Not connected internally.

+ IN B (Pin 7): Noninverting Input of B Channel Amplifier.

– IN B (Pin 8): Inverting Input of B Channel Amplifier.

EN B (Pin 9): B Channel Enable Pin. Logic low to enable.

OUT B (Pin 10): B Channel Output.

GND (Pins 12, 13): Ground. Not connected internally.

OUT A (Pin 15): A Channel Output.

EN A (Pin 16): A Channel Enable Pin. Logic low to enable.