參數(shù)資料
型號： MAX4189ESD+T
廠商： Maxim Integrated Products
文件頁數(shù)： 8/23頁
文件大?。?/td> 0K
描述： IC AMP CURRENT SENSE 14-SOIC
標準包裝： 2,500
應(yīng)用： 電流反饋
電路數(shù)： 3
-3db帶寬： 250MHz
轉(zhuǎn)換速率： 175 V/µs
電流 - 電源： 1.5mA
電流 - 輸出 / 通道： 55mA
電壓 - 電源，單路/雙路(±)： 4.5 V ~ 11 V，±2.25 V ~ 5.5 V
安裝類型： 表面貼裝
封裝/外殼： 14-SOIC（0.154"，3.90mm 寬）
供應(yīng)商設(shè)備封裝： 14-SOIC
包裝： 帶卷 (TR)
MAX4188/MAX4189/MAX4190
Single/Triple, Low-Glitch, 250MHz, Current-
Feedback Amplifiers with High-Speed Disable
16
______________________________________________________________________________________
amplifiers achieve very high isolation from input to output
(65dB at 10MHz), and the outputs are placed into a high-
impedance state. These amplifiers achieve low switch-
ing-transient glitches (<45mVP-P) when switching
between enable and disable modes. Fast enable/disable
times (120ns/35ns), along with high off-isolation and low
switching transients, allow these devices to be used as
high-performance, high-speed multiplexers. This is
achieved by connecting the outputs of multiple amplifiers
together and controlling the DISABLE inputs to enable
one amplifier and disable all others. The disabled ampli-
fiers present a very light load (1A leakage current and
3.5pF capacitance) to the active amplifier’s output. The
feedback network impedance of all the disabled ampli-
fiers must still be considered when calculating the total
load on the active amplifier output. Figure 1 shows an
application circuit using the MAX4188 as a 3:1 video mul-
tiplexer.
The DISABLE_ logic threshold is typically VCC - 2.5V,
independent of VEE. For a single +5V supply or dual
±5V supplies, the disable inputs are CMOS-logic com-
patible. The amplifiers default to the enabled mode if
the DISABLE pin is left unconnected. If the DISABLE
pin is left floating, take proper care to ensure that no
high-frequency signals are coupled to this pin, as this
may cause false triggering.
Applications Information
Theory of Operation
The MAX4188/MAX4189/MAX4190 are current-feedback
amplifiers, and their open-loop transfer function is
expressed as a transimpedance, VOUT/IIN, or TZ. The
frequency behavior of the open-loop transimpedance is
similar to the open-loop gain of a voltage-mode feedback
amplifier. That is, it has a large DC value and decreases
at approximately 6dB per octave.
Analyzing the follower with gain, as shown in Figure 2,
yields the following transfer function:
VOUT / VIN = G x [(TZ (S) / TZ(s) + G x (RIN + RF)]
where G = AVCL = 1 + (RF / RG), and RIN = 1/gM
300.
At low gains, G x RIN < RF. Therefore, the closed-loop
bandwidth is essentially independent of closed-loop
gain. Similarly TZ > RF at low frequencies, so that:
V
OUT
IN
(
/
)
==
+
GR
R
FG
1
VIN
RG
RIN
TZ
RF
+1
VOUT
MAX4188
MAX4189
MAX4190
Figure 2. Current-Feedback Amplifier
AMP1
6
7
5
560
75
VIN1
560
1.0F
0.1F
4
11
+5V
-5V
0.1F
87
AMP2
13
14
12
9
10
DISABLE2
DISABLE3
DISABLE1
560
75
VIN2
560
VOUT
87
75
75