LT3092MPST#TRPBF【PDF 9/22 页】IC PROG CURRENT SOURCE SOT223-3

收藏本站

您好，
买卖IC网欢迎您。
请登录
免费注册

买卖IC网

Sheet目录41

5页 6页 7页 8页 [9页]10页 11页 12页 13页

LT3092

3092fb

APPLICATIONS INFORMATION

inductive components and may be complex distributed

networks. In addition, the current sources value will dif-

fer between applications and its connection may be GND

referenced, power supply referenced or oating in a signal

line path. Linear Technology strongly recommends that

stability be tested in situ for any LT3092 application.

In LT3092 applications with long wires or PCB traces, the

inductive reactance may cause instability. In some cases,

adding series resistance to the input and output lines (as

shown in Figure 2) may suf ciently dampen these possible

high-Q lines and provide stability. The user must evaluate

the required resistor values against the designs headroom

constraints. In general, operation at low output current

levels (< 5mA) automatically requires higher values of

programming resistors and may provide the necessary

damping without additional series impedance.

If the line impedances in series with the LT3092 are

complex enough such that series damping resistors are

not suf cient, a frequency compensation network may be

necessary. Several options may be considered.

From this point, selecting R

OUT

is easy, as it is a straight-

forward calculation from R

SET

. Take note, however, resistor

errors must be accounted for as well. While larger voltage

drops across R

SET

minimize the error due to offset, they

also increase the required operating headroom.

Obtaining the best temperature coef cient does not require

the use of expensive resistors with low ppm temperature

coef cients. Instead, since the output current of the LT3092

is determined by the ratio of R

SET

to R

OUT

, those resistors

should have matching temperature characteristics. Less

expensive resistors made from the same material will

provide matching temperature coef cients. See resistor

manufacturers data sheets for more details.

Stability and Frequency Compensation

The LT3092 does not require input or output capacitors

for stability in many current-source applications. Clean,

tight PCB layouts provide a low reactance, well controlled

operating environment for the LT3092 without requiring

capacitors to frequency-compensate the circuit. The front

page Typical Application circuit illustrates the simplicity

of using the LT3092.

Some current source applications will use a capacitor

connected in parallel with the SET pin resistor to lower

the current sources noise. This capacitor also provides a

soft-start function for the current source. This capacitor

connection is depicted in Figure 7 (see the Quieting the

Noise section).

When operating with a capacitor across the SET pin resis-

tor, external compensation is usually required to maintain

stability and compensate for the introduced pole. The

following paragraphs discuss methods for stabilizing

the LT3092 for either this capacitance or other complex

impedances that may be presented to the device. Linear

Technology strongly recommends testing stability in situ

with nal components before beginning production.

Although the LT3092s design strives to be stable without

any capacitors over a wide variety of operating conditions,

it is not possible to test for all possible combinations of

input and output impedances that the LT3092 will encounter.

These impedances may include resistive, capacitive and

Figure 2. Adding Series Resistor Decouples

and Dampens Long Line Reactances

SET

OUT

LT3092

10糀

SET

OUT

SERIES

LONG LINE

REACTANCE/INDUCTANCE

3092 F02

LONG LINE

REACTANCE/INDUCTANCE

发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

*型号	*数量	厂商	批号	封装

添加更多采购

采购需求

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

我的联系方式