參數資料
| 型號： | LT1787HVCS8#PBF |
| 廠商： | Linear Technology |
| 文件頁數： | 2/16頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC AMP PREC CURR-SENSE 8-SOIC |
| 標準包裝： | 100 |
| 放大器類型： | 電流檢測 |
| 電路數： | 1 |
| 電壓 - 輸入偏移： | 40µV |
| 電流 - 電源： | 60µA |
| 電流 - 輸出 / 通道： | 50µA |
| 電壓 - 電源，單路/雙路(±)： | 2.5 V ~ 60 V，±1.25 V ~ 30 V |
| 工作溫度： | 0°C ~ 70°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 8-SOIC（0.154"，3.90mm 寬） |
| 供應商設備封裝： | 8-SO |
| 包裝： | 管件 |
| 產品目錄頁面： | 1319 (CN2011-ZH PDF) |
10
LT1787/LT1787HV
1787fc
The LT1787 high side current sense amplifier (Figure 1)
provides accurate bidirectional monitoring of current
through a user-selected sense resistor. The sense voltage
is amplified by a fixed gain of 8 and level shifted from the
positive power supply to the ground referenced outputs.
The output signal may be used in a variety of ways to
interface with subsequent signal processing circuitry.
Input and output filtering are easily implemented to elimi-
nate aliasing errors.
Theory of Operation
Inputs VS+ and VS– apply the sense voltage to matched
resistors RG1 and RG2. The opposite ends of resistors RG1
and RG2 are forced to be at equal potentials by the voltage
gain of amplifier A1. The currents through RG1 and RG2 are
forced to flow through transistors Q1 and Q2 and are
summed at node VOUT by the 1:1 current mirror. The net
current from RG1 and RG2 flowing through resistor ROUT
gives a voltage gain of eight. Positive sense voltages result
in VOUT being positive with respect to pin VBIAS.
Pins VEE, VBIAS and VOUT may be connected in a variety of
ways to interface with subsequent circuitry. Split supply
and single supply output configurations are shown in the
following sections.
Supply current for amplifier A1 is drawn from the VS– pin.
The user may choose to include this current in the moni-
tored current through RSENSE by careful choice of connec-
tion polarity.
Selection of External Current Sense Resistor
External RSENSE resistor selection is a delicate trade-off
between power dissipation in the resistor and current
measurement accuracy. The LT1787 makes this decision
less difficult than with competitors’ products. The maxi-
mum sense voltage may be as large as
±500mV to get
maximum resolution, however, high current applications
will not want to suffer this much power dissipation in the
sense resistor. The LT1787’s input offset voltage of 40
V
gives high resolution for low sense voltages. This wide
operating dynamic range gives the user wide latitude in
tailoring the range and resolution of his supply monitoring
function.
APPLICATIONS INFORMATION
WU
U
Kelvin connection of the LT1787’s VS+ and VS– inputs to
the sense resistor should be used in all but the lowest
power applications. Solder connections and PC board
interconnect resistance (approximately 0.5m
persquare)
can be a large error in high current systems. A 5-Amp
application might choose a 20m
sense resistor to give a
100mV full-scale input to the LT1787. Input offset voltage
will limit resolution to 2mA. Neglecting contact resistance
at solder joints, even one square of PC board copper at
each resistor end will cause an error of 5%. This error will
grow proportionately higher as monitored current levels
rise to tens or hundreds of amperes.
Input Noise Filtering
The LT1787 provides input signal filtering pins FIL+ and
FIL– that are internally connected to the midpoint taps of
resistors RG1 and RG2. These pins may be used to filter the
input signal entering the LT1787’s internal amplifier, and
should be used when fast current ripple or transients may
flow through the sense resistor. High frequency signals
above the 300kHz bandwidth of the LT1787’s internal
amplifier will cause errors. A capacitor connected between
FIL+ and FIL– creates a single pole low pass filter with
corner frequency:
f–3dB = 1/(2πRC)
where R = 1.25k. A 0.01
F capacitor creates a pole at
12.7kHz, a good choice for many applications.
Common mode filtering from the FIL+ and FIL– pins should
not be attempted, as mismatch in the capacitors from FIL+
and FIL– will create AC common mode errors. Common
mode filtering must be done at the power supply output.
Output Signal Range
The LT1787’s output signal is developed by summing the
net currents through RG1 and RG2 into output resistor
ROUT. The pins VOUT and VBIAS may be connected in
numerous configurations to interface with following cir-
cuitry in either single supply or split supply applications.
Care must be used in connecting the output pins to
preserve signal accuracy. Limitations on the signal swing
at VOUT are imposed by the negative supply, VEE, and the
input voltage VS+. In the negative direction, internal circuit
saturation with loss of accuracy occurs for VOUT < 70mV
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| LT1787HVHS8 | 功能描述:IC PREC AMP CURRENT SENSE 8-SOIC RoHS:否 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:1 系列:- 放大器類型:通用 電路數:4 輸出類型:滿擺幅 轉換速率:0.028 V/µs 增益帶寬積:105kHz -3db帶寬:- 電流 - 輸入偏壓:3nA 電壓 - 輸入偏移:100µV 電流 - 電源:3.3µA 電流 - 輸出 / 通道:12mA 電壓 - 電源，單路/雙路(±):2.7 V ~ 12 V，±1.35 V ~ 6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:14-TSSOP（0.173"，4.40mm 寬） 供應商設備封裝:14-TSSOP 包裝:剪切帶 (CT) 其它名稱:OP481GRUZ-REELCT |
| LT1787HVHS8#PBF | 功能描述:IC PREC AMP CURRENT SENSE 8-SOIC RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:1 系列:- 放大器類型:通用 電路數:4 輸出類型:滿擺幅 轉換速率:0.028 V/µs 增益帶寬積:105kHz -3db帶寬:- 電流 - 輸入偏壓:3nA 電壓 - 輸入偏移:100µV 電流 - 電源:3.3µA 電流 - 輸出 / 通道:12mA 電壓 - 電源，單路/雙路(±):2.7 V ~ 12 V，±1.35 V ~ 6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:14-TSSOP（0.173"，4.40mm 寬） 供應商設備封裝:14-TSSOP 包裝:剪切帶 (CT) 其它名稱:OP481GRUZ-REELCT |
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| LT1787HVHS8#TRPBF | 功能描述:IC PREC AMP CURRENT SENSE 8-SOIC RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標準包裝:50 系列:- 放大器類型:J-FET 電路數:2 輸出類型:- 轉換速率:3.5 V/µs 增益帶寬積:1MHz -3db帶寬:- 電流 - 輸入偏壓:30pA 電壓 - 輸入偏移:2000µV 電流 - 電源:200µA 電流 - 輸出 / 通道:- 電壓 - 電源，單路/雙路(±):7 V ~ 36 V，±3.5 V ~ 18 V 工作溫度:0°C ~ 70°C 安裝類型:通孔 封裝/外殼:8-DIP（0.300"，7.62mm） 供應商設備封裝:8-PDIP 包裝:管件 |
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