TC815CBU View Datasheet(PDF) - Microchip Technology
Part Name
Description
Manufacturer
TC815CBU
Microchip Technology
TC815CBU Datasheet PDF : 26 Pages
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Vendors for piezo electric audio transducers are:
• Gulton Industries
Piezo Products Division
212 Durham Avenue
Metuchen, New Jersey 08840
(201) 548-2800
Typical P/Ns: 102-95NS, 101-FB-00
• Taiyo Yuden (USA) Inc.
Arlington Center
714 West Algonquin Road
Arlington Heights, Illinois 60005
Typical P/Ns: CB27BB, CB20BB, CB355BB
11.1 Display Decimal Point Selection
The TC815 provides a decimal point LCD drive signal.
The decimal point position is a function of the selected
full scale range, as shown in Table 11-1.
TABLE 11-1: DECIMAL POINT SELECTION
1*9
*9
*9
Full Scale Range
2000V, 2000kΩ
200V, 200.0kΩ
20V, 20.00kΩ
2V, 2.000kΩ
200V, 200.0Ω
200mV, 200.0Ω
20mA
200mA
DP3
OFF
OFF
OFF
ON
OFF
OFF
OFF
OFF
DP2
OFF
OFF
ON
OFF
OFF
OFF
ON
OFF
DP1
OFF
ON
OFF
OFF
OFF
ON
OFF
ON
11.2 AC-to-DC Converter Operational
Amplifier
The TC815 contains an on-chip operational amplifier
that may be connected as a rectifier for AC-to-DC volt-
age and current measurements. Typical operational
amplifier characteristics are:
• Slew Rate: 1 V/µsec
• Unity-Gain Bandwidth: 0.4MHz
• Open Loop Gain: 44dB
• Output Voltage Swing (Load = 10kΩ) ± 1.5V
(Referenced to Analog Common)
When the AC measurement option is selected, the
input buffer receives an input signal through switch
S14, rather than switch S11. With external circuits, the
AC Operating mode can be used to perform other types
of functions within the constraints of the internal opera-
tional amplifier. External circuits that perform true RMS
conversion, or a peak hold function are typical
examples.
TC815
11.3 Component Selection
11.3.1
INTEGRATION RESISTOR
SELECTION
The TC815 automatically selects one of two external
integration resistors. RVBUF (pin 55) is selected for
voltage and current measurement. RΩBUF (Pin 54) is
selected for resistance measurements.
11.3.2 RVIBUF SELECTION (PIN 55)
In auto-range operation, the TC815 operates with a
200mV maximum full scale potential at VI (Pin 44).
Resistive dividers at VR2 (Pin 41), VR3 (Pin 40), VR4
(Pin 43), and VR5 (Pin 42) are automatically switched
to maintain the 200V full scale potential.
In Manual mode, the Extended Operating mode is acti-
vated, giving a 300mV full scale potential at VI (Pin 44).
The integrator output swing should be maximized, but
saturations must be avoided. The integrator will swing
within 0.45V of VCC (Pin 28) and 0.5V of VSS (Pin 57)
without saturating. A ±2V swing is suggested. The
value of RVIBUF is easily calculated, assuming a worst
case extended resolution input signal:
VINT = Integrator swing = ±2V
tI
= Integration time = 100msec
CI = Integration capacitor = 0.1µF
VMAX = Maximum input at VI = 300mV
EQUATION 11-1:
RVIBUF =
VMAX(TI)
VINT(CI)
= 150kΩ
11.3.3 RΩBUF SELECTION (PIN 54)
In ratiometric resistance measurements, the signal at
RX (pin 50) is always positive, with respect to analog
common. The integrator swings negative.
The worst case integrator swing is for the 200Ω range
with the manual, extended resolution option.
The input voltage, VX (Pin 50) is easily calculated (see
Figure 11-2):
VANCOM = Potential at Analog Common ≈ 2.7V
R8
= 220Ω
RI
= 163.85Ω
RX
= 300Ω
RS
= Internal switch 33 resistance ≈ 600Ω
EQUATION 11-2:
RΩBUF =
VCC - (VANCOM)RX
(RX + RS + R1 + R8)
= 0.63V
© 2002 Microchip Technology Inc.
DS21474B-page 21
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