Datasheet LT1010 (Analog Devices) - 9

LT1010
APPLICATIONS INFORMATION
The offset voltage specified for VS = ±15V, VIN = 0V and At lower frequencies, the buffer is within the feedback loop TA = 25°C will suffice for a worst-case condition. so that its offset voltage and gain errors are negligible. At higher frequencies, feedback is through CF , so that phase V+ shift from the load capacitance acting against the buffer output resistance does not cause loop instability. IS IS Stability depends upon the RFCF time constant or the A1 closed-loop bandwidth. With an 80kHz bandwidth, ring- VIN LT1010 VOUT ing is negligible for CL = 0.068µF and damps rapidly for C ∆I L = 0.33µF. The pulse response is shown in the graph. OUT
Pulse Response
A2 LT1010 CL = 0.068µF I 5 S – ∆IOUT IS + ∆IOUT 0 1010 AI03 V– –5 Output load current will be divided based on the output CL = 0.33µF 5 resistance of the individual buffers. Therefore, the avail- OUTPUT VOLTAGE (V) able output current will not quite be doubled unless output 0 resistances are matched. As for offset voltage, the 25°C –5 limits should be used for worst-case calculations. 0 50 100 150 200 Parallel operation is not thermally unstable. Should one TIME (µs) unit get hotter than its mates, its share of the output and 1010 AI05 its standby dissipation will decrease. Small-signal bandwidth is reduced by CF , but considerable isolation can be obtained without reducing it below the As a practical matter, parallel connection needs only some power bandwidth. Often, a bandwidth reduction is desirable increased attention to heat sinking. In some applications, to filter high frequency noise or unwanted signals. a few ohms equalization resistance in each output may be wise. Only the most demanding applications should require RF matching, and then just of output resistance at 25°C. 2k C
Isolating Capacitive Loads
F 1nF – A1 A2 The inverting amplifier below shows the recommended RS LT118A LT1010 V 2k OUT method of isolating capacitive loads. Noninverting ampli- VIN + CL fiers are handled similarly. 1010 AI06 RF R The follower configuration is unique in that capacitive S 20k VIN load isolation is obtained without a reduction in small- CF signal bandwidth, although the output impedance of the 100pF – buffer comes into play at high frequencies. The precision A1 A2 LT1007 LT1010 VOUT unity-gain buffer above has a 10MHz bandwidth without + CL capacitive loading, yet it is stable for all load capacitance 1010 AI04 to over 0.3µF, again determined by RFCF . 1010fe 9 Document Outline Fteatures Applications Description Typical Application Absolute Maximum Ratings Preconditioning Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Applications Information Schematic Diagram Definition Of Terms Package Description Revision History Related Parts