LT1010CDD datasheet(9/20 Pages) LINER

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LT1010

1010fc

be unrealistic to use these worst-case numbers above

because paralleled units are operating under identical

conditions. The offset voltage specified for VS = ±15V,

VIN = 0V and TA = 25°C will suffice for a worst-case

condition.

APPLICATIO S I FOR ATIO

At lower frequencies, the buffer is within the feedback loop

so that its offset voltage and gain errors are negligible. At

higher frequencies, feedback is through CF, so that phase

shift from the load capacitance acting against the buffer

output resistance does not cause loop instability.

Stability depends upon the RFCF time constant or the

closed-loop bandwidth. With an 80kHz bandwidth, ring-

ing is negligible for CL = 0.068µF and damps rapidly for

CL = 0.33µF. The pulse response is shown in the graph.

LT1010

VIN

V–

LT1010

V+

∆IOUT

IS + ∆IOUT

IS – ∆IOUT

VOUT

1010 AI03

LT1010

20k

VIN

100pF

1010 AI04

VOUT

–

LT1007

Output load current will be divided based on the output

resistance of the individual buffers. Therefore, the avail-

able output current will not quite be doubled unless output

resistances are matched. As for offset voltage, the 25

°C

limits should be used for worst-case calculations.

Parallel operation is not thermally unstable. Should one

unit get hotter than its mates, its share of the output and

its standby dissipation will decrease.

As a practical matter, parallel connection needs only some

increased attention to heat sinking. In some applications,

a few ohms equalization resistance in each output may be

wise. Only the most demanding applications should re-

quire matching, and then just of output resistance at 25

°C.

Isolating Capacitive Loads

The inverting amplifier below shows the recommended

method of isolating capacitive loads. Noninverting ampli-

fiers are handled similarly.

TIME (

µs)

200

1010 AI05

100

150

–5

CL = 0.068µF

CL = 0.33µF

Pulse Response

Small-signal bandwidth is reduced by CF, but consider-

able isolation can be obtained without reducing it below

the power bandwidth. Often, a bandwidth reduction is

desirable to filter high frequency noise or unwanted

signals.

LT1010

VIN

1nF

1010 AI06

VOUT

–

LT118A

The follower configuration is unique in that capacitive

load isolation is obtained without a reduction in small-

signal bandwidth, although the output impedance of the

buffer comes into play at high frequencies. The precision

unity-gain buffer above has a 10MHz bandwidth without

capacitive loading, yet it is stable for all load capacitance

to over 0.3

µF, again determined by RFCF.

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