LT1206C(Rev0) 데이터 시트보기 (PDF) - Linear Technology

부품명

상세내역

제조사

LT1206C
(Rev.:Rev0)

250mA/60MHz Current Feedback Amplifier

Linear Technology 

LT1206

APPLICATI S I FOR ATIO

the maximum allowable input voltage. To allow for some

margin, it is recommended that the input signal be less

than ±5V when the device is shut down.

RF = 750Ω

RL = 50Ω

LT1206 • F04c

Figure 5c. Large-Signal Response, AV = 2

When the LT1206 is used to drive capacitive loads, the

available output current can limit the overall slew rate. In

the fastest configuration, the LT1206 is capable of a slew

rate of over 1V/ns. The current required to slew a capacitor

at this rate is 1mA per picofarad of capacitance, so

10,000pF would require 10A! The photo (Figure 6) shows

the large signal behavior with CL = 10,000pF. The slew rate

is about 60V/µs, determined by the current limit of 600mA.

Capacitance on the Inverting Input

Current feedback amplifiers require resistive feedback

from the output to the inverting input for stable operation.

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), but it

does not degrade the stability of the amplifier.

Power Supplies

The LT1206 will operate from single or split supplies from

±5V (10V total) to ±15V (30V total). It is not necessary to

use equal value split supplies, however the offset voltage

and inverting input bias current will change. The offset

voltage changes about 500µV per volt of supply mis-

match. The inverting bias current can change as much as

5µA per volt of supply mismatch, though typically the

change is less than 0.5µA per volt.

VS = ±15V

RF = RG = 3k

RL = ∞

LT1206 • F06

Figure 6. Large-Signal Response, CL = 10,000pF

Differential Input Signal Swing

The differential input swing is limited to about ±6V by an

ESD protection device connected between the inputs. In

normal operation, the differential voltage between the

input pins is small, so this clamp has no effect; however,

in the shutdown mode the differential swing can be the

same as the input swing. The clamp voltage will then set

Thermal Considerations

The LT1206 contains a thermal shutdown feature which

protects against excessive internal (junction) tempera-

ture. If the junction temperature of the device exceeds the

protection threshold, the device will begin cycling be-

tween normal operation and an off state. The cycling is not

harmful to the part. The thermal cycling occurs at a slow

rate, typically 10ms to several seconds, which depends on

the power dissipation and the thermal time constants of

the package and heat sinking. Raising the ambient tem-

perature until the device begins thermal shutdown gives a

good indication of how much margin there is in the

thermal design.

For surface mount devices heat sinking is accomplished

by using the heat spreading capabilities of the PC board

and its copper traces. Experiments have shown that the

heat spreading copper layer does not need to be electri-

cally connected to the tab of the device. The PCB material

can be very effective at transmitting heat between the pad

area attached to the tab of the device, and a ground or

11

Share Link: