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| 型号： | LTC1531 |
| 厂商： | Linear Technology Corporation |
| 英文描述： | Self-Powered Isolated Comparator |
| 中文描述： | 自供电隔离比较 |
| 文件页数： | 8/16页 |
| 文件大小： | 266K |
| 代理商： | LTC1531 |
8
LTC1531
The zero-cross comparator inputs, ZCPOS and ZCNEG,
have an input common mode range that allows signal
swings near the positive supply rails. The ZCPOS and
ZCNEG inputs contain ESD diode protection devices which
will clamp input signals that go below GND. The current
into the diode should be limited to less than 5mA. The
Isolated Thermistor Temperature Controller shows an
example phase shift network with attenuation that satis-
fies these conditions. The positive input voltage should
not exceed the 12V maximum rating or the 5mA input
current to the ESD diode clamp.
ISOLATION dV/dt
The maximum continuous dV/dt across the isolation bar-
rier that will still allow the isolated comparator to operate
is 50V/
μ
s. Continuous rates of dV/dt greater than this
cause the isolated side to not detect when its power cycle
has stopped and a comparison should begin. Figure 4
shows the maximum continuous rate trade-off of fre-
quency vs voltage of a sine wave:
SR = (
π
)(f)(V
P-P
)
where SR = slew rate, V
P-P
= the peak-to-peak voltage and
f = frequency. Noise immunity to intermittent dV/dt rates
greater than 50V/
μ
s can be rejected by the LTC1531.
AC Noise Rejection and Things to Avoid
Minimizing AC noise pickup at the isolated comparator
should follow the following guidelines.
1. Allow the isolated side ground to float. The isolated side
should only be common with the isolated circuit.
2. Use hysteresis to decrease sensitivity by using CMPOUT.
3. Use lower impedance circuits if powered by V
REG
.
Avoid large capacitance tied directly to V
REG
output,
since this output does not go Hi-Z (high impedance)
during the off time.
PC Board Layout
The PC board layout should not have copper near the lead
frame isolation capacitors. The copper reduces the power
coupling and power delivery to the isolated side (see
Figure 6).
APPLICATIO
S I
N
FOR
ATIO
U
W
U
TYPICAL APPLICATIONS DESCRIPTION
The Isolated Thermistor Temperature Controller (front
page) uses a simple AC power rectifier and Zener to
provide 5.6V of DC power to the LTC1531. To avoid power
dissipation in the 3k, 3W resistor, DC power can be
provided with a charge pump circuit similar to the Isolated
Switch Control. In this circuit, a thermistor half bridge is
used with the 4-input comparator connected to provide
the other half of the bridge, V4 = 2.5V, V3 = 0V, giving
(V4 + V3)/2 = 1.25V. With the 50k pot set to about 30k, the
trip point is 25
°
C with a hysteresis of
±
0.5
°
C. Here, V
REG
turns on and powers the half-bridge while the comparator
samples the result. The zero-cross comparator, ZCPOS
and ZCNEG, is used to trigger a triac at the 10
°
phase point.
The circuit, R1, R2 and C1, provides the phase shift,
θ
, as
determined by:
R2C1
tan(
θ
)/2
π
60Hz
and where the attenuation
R2/R1. In this example,
R1 = 680k, R2 = 47k and C1 = 0.01
μ
F, provide a 7V peak
input signal with 10
°
of phase lag.
Figure 6. PC Board Layout Consideration
1
2
3
4
11
12
13
14
28
27
26
25
18
17
16
15
V
CC
SHDN
ZCNEG
ZCPOS
V
PW
CMPOUT
V
REG
ISOGND
GND
ZCDATA
DATA
VALID
ETCH COPPER
FROM THE
SHADED AREA
V1
V2
V3
V4
SW PACKAGE
28-LEAD PLASTIC SO (ISO)
TOP VIEW
1531 F06
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1531CSW | 功能描述:IC COMP ISOLATED SLF-PWRD 28SOIC RoHS:否 类别:集成电路 (IC) >> 线性 - 比较器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 类型:通用 元件数:1 输出类型:CMOS，推挽式，满摆幅，TTL 电压 - 电源，单路/双路(±):2.5 V ~ 5.5 V，±1.25 V ~ 2.75 V 电压 - 输入偏移（最小值）:5mV @ 5.5V 电流 - 输入偏压（最小值）:1pA @ 5.5V 电流 - 输出（标准）:- 电流 - 静态（最大值）:24µA CMRR, PSRR（标准）:80dB CMRR，80dB PSRR 传输延迟（最大）:450ns 磁滞:±3mV 工作温度:-40°C ~ 85°C 封装/外壳:6-WFBGA，CSPBGA 安装类型:表面贴装 包装:管件 其它名称:Q3554586 |
| LTC1531CSW#PBF | 功能描述:IC COMP ISOLATED SLF-PWRD 28SOIC RoHS:是 类别:集成电路 (IC) >> 线性 - 比较器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 类型:通用 元件数:1 输出类型:CMOS，推挽式，满摆幅，TTL 电压 - 电源，单路/双路(±):2.5 V ~ 5.5 V，±1.25 V ~ 2.75 V 电压 - 输入偏移（最小值）:5mV @ 5.5V 电流 - 输入偏压（最小值）:1pA @ 5.5V 电流 - 输出（标准）:- 电流 - 静态（最大值）:24µA CMRR, PSRR（标准）:80dB CMRR，80dB PSRR 传输延迟（最大）:450ns 磁滞:±3mV 工作温度:-40°C ~ 85°C 封装/外壳:6-WFBGA，CSPBGA 安装类型:表面贴装 包装:管件 其它名称:Q3554586 |
| LTC1531CSW#TR | 功能描述:IC COMP DIFF DUAL SELFPWR 28SOIC RoHS:否 类别:集成电路 (IC) >> 线性 - 比较器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 类型:通用 元件数:1 输出类型:CMOS，推挽式，满摆幅，TTL 电压 - 电源，单路/双路(±):2.5 V ~ 5.5 V，±1.25 V ~ 2.75 V 电压 - 输入偏移（最小值）:5mV @ 5.5V 电流 - 输入偏压（最小值）:1pA @ 5.5V 电流 - 输出（标准）:- 电流 - 静态（最大值）:24µA CMRR, PSRR（标准）:80dB CMRR，80dB PSRR 传输延迟（最大）:450ns 磁滞:±3mV 工作温度:-40°C ~ 85°C 封装/外壳:6-WFBGA，CSPBGA 安装类型:表面贴装 包装:管件 其它名称:Q3554586 |
| LTC1531CSW#TRPBF | 功能描述:IC COMP ISOLATED SLF-PWRD 28SOIC RoHS:是 类别:集成电路 (IC) >> 线性 - 比较器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 类型:通用 元件数:1 输出类型:CMOS，推挽式，满摆幅，TTL 电压 - 电源，单路/双路(±):2.5 V ~ 5.5 V，±1.25 V ~ 2.75 V 电压 - 输入偏移（最小值）:5mV @ 5.5V 电流 - 输入偏压（最小值）:1pA @ 5.5V 电流 - 输出（标准）:- 电流 - 静态（最大值）:24µA CMRR, PSRR（标准）:80dB CMRR，80dB PSRR 传输延迟（最大）:450ns 磁滞:±3mV 工作温度:-40°C ~ 85°C 封装/外壳:6-WFBGA，CSPBGA 安装类型:表面贴装 包装:管件 其它名称:Q3554586 |
| LTC1531IS8 | 制造商:Linear Technology 功能描述:Self-Powered Isolated Comparator |
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