MAX4556C 데이터 시트보기 (PDF) - Maxim Integrated
부품명
상세내역
제조사
MAX4556C Datasheet PDF : 28 Pages
| |||
Force-Sense Switches
Figure 8 shows how to switch a single guarded voltage
or current source between two grounded loads using a
MAX4555. By interchanging loads and sources, the cir-
cuits can be reversed so that two sources are switched
to a single load.
Switching 8-Wire Guarded Circuits
Figure 9 shows how to switch a single 8-wire guarded
force-sense voltage or current source between two
loads using two MAX4556s or two MAX4554s. By inter-
changing loads and sources, the circuits can be
reversed so that they switch two sources to a single
load. The two loads are shown isolated from each
another, but if they have a common connection then the
circuit must remain as shown in order to maintain accu-
rate load voltage.
High-Frequency Performance
Although switching speed is restricted, once a switch is
in a steady state it exhibits good RF performance. In
50Ω systems, signal response is reasonably flat up to
50MHz (see Typical Operating Characteristics). The
force switches have lower on-resistance, so their inser-
tion loss in 50Ω systems is lower. Above 20MHz, the
on-response has several minor peaks that are highly
layout dependent. The problem with high-frequency
operation is not turning the switches on, but turning
them off. The off-state switches act like capacitors and
pass higher frequencies with less attenuation. At
10MHz, off-isolation between input or output signals is
approximately -30dB in 50Ω systems, degrading
(approximately 20dB per decade) as frequency
increases. Higher circuit impedances also degrade off-
isolation.
GUARD AMPLIFIER
VOLTAGE OR
CURRENT SOURCE
IN
LOGIC
IN
LOAD
0
2
1
1
V+
V-
VL
COM1
COM2
MAX4555
NC1
NC2
COM3
NC3
COM4
IN1
NC4
IN2
GND
IN3
IN4
Figure 8. Using the MAX4555 to Switch 3-Wire Guarded Circuits from One Source to Two Loads
LOAD2
LOAD1
______________________________________________________________________________________ 23
Share Link: 