VRE100 Просмотр технического описания (PDF) - Cirrus Logic
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VRE100 Datasheet PDF : 5 Pages
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Product Innova tionFrom
VRE100
Selection Guide
Model
VRE100C
VRE100CA
VRE100M
VRE100MA
VRE101C
VRE101CA
VRE101M
VRE100MA
VRE102C
VRE102CA
VRE102M
VRE102MA
Output (V)
+10
+10
+10
+10
-10
-10
-10
-10
±10
±10
±10
±10
Temperature
Operating Range
-25°C to +85°C
-25°C to +85°C
-55°C to +125°C
-55°C to +125°C
-25°C to +85°C
-25°C to +85°C
-55°C to +125°C
-55°C to +125°C
-25°C to +85°C
-25°C to +85°C
-55°C to +125°C
-55°C to +125°C
Volt Deviation (MAX)
±0.6mV
±0.3mV
±1.0mV
±0.5mV
±0.6mV
±0.3mV
±1.0mV
±0.5mV
±0.6mV
±0.3mV
±1.0mV
±0.5mV
Hermetic 14-pin Ceramic DIP
Package Style HC
2. THEORY OF OPERATION
The following discussion refers to the block diagrams in Figure 1. In operation, approximately 6.3 volts is applied
to the noninverting input of the op amp. The voltage is amplified by the op amp to produce a 10.000 V output. The
gain is determined by the networks R1 and R2: G=1 + R2/R1. The 6.3 V zener diode is used because it is the most
stable diode over time and temperature.
The zener operating current is derived from the regulated output voltage through R3. This feedback arrangement
provides a closely regulated zener current. This current determines the slope of the references’ voltage vs. tempera-
ture function. By trimming the zener current a lower drift over temperature can be achieved. But since the voltage
vs. temperature function is nonlinear this compensation technique is not well suited for wide temperature ranges.
A nonlinear compensation network of thermistors and resistors is used in the VRE series voltage references. This
proprietary network eliminates most of the nonlinearity in the voltage vs. temperature function. By then adjusting the
slope, this series produces a very stable voltage over wide temperature ranges. This network is less than 2% of the
overall network resistance so it has a negligible effect on long term stability. By using highly stable resistors in our
network, we produce a voltage reference that also has very good long term stability.
3. APPLICATION INFORMATION
Page 5 shows the proper connection of the VRE100 series voltage reference with the optional trim resistors. When
trimming the VRE102, the positive voltage should be trimmed first since the negative voltage tracks the positive
side. Pay careful attention to the circuit layout to avoid noise pickup and voltage drops in the lines.
The VRE100 series voltage references have the ground terminal brought out on two pins (pin 6 and pin 7) which
are connected together internally. This allows the user to achieve greater accuracy when using a socket. Voltage
references have a voltage drop across their power supply ground pin due to quiescent current flowing through the
contact resistance. If the contact resistance was constant with time and temperature, this voltage drop could be
trimmed out. When the reference is plugged into a socket, this source of error can be as high as 20 ppm. By con-
necting pin 7 to the power supply ground and pin 6 to a high impedance ground point in the measurement circuit,
the error due to the contact resistance can be eliminated. If the unit is soldered into place the contact resistance is
sufficiently small that it doesn’t effect performance. The VRE series voltage references can be connected with or
without the use of pin 6 and still provide superior performance.
VRE100DS
3
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