ame7106 AME, Inc., ame7106 Datasheet - Page 7

• Manufacturer Part Number: ame7106
• Description: 3-1/2 Digit A/d Converter High Accuracy, Low Power
• Manufacturer: AME, Inc.

The A/D conversion has the following three phases:
Auto-Zero Phase
ternally. The reference capacitor is charged to the refer-
ence voltage. A feedback loop is closed around the sys-
tem to cancel the offset voltage of buffer, integrator and
comparator.
Signal Integration phase
the INHI and INLO for a fixed time, 1000 system clocks.
The polarity of the signal is determined at the end of this
phase.
Reference Integration Phase
INHI is connected across the reference capacitor with ap-
propriate polarity determined by the control circuit. The
integrator output will then return to zero. The time it takes
to return to zero, 1000 X VIN /VREF, is the digital repre-
sentation of the analog signal.
n Function Description
Rev.H.02
AME7106 / 7106A / 7106R
AME7107 / 7107A / 7107R
The INHI and INLO are shorted to analog common in-
The converter integrates the differential voltage across
INLO is internally connected to the Analog Common,
1) Auto-Zero Phase
2) Integration Phase
3) De-integration Phase
AME, Inc.
Figure4. Analog Section
Differential Signal Inputs (INHI & INLO)
accepts input signals within the input common mode volt-
age range (Vcm). Typical range is from 1V above the V-
to 1V below the V+. The integrator output can swing
within 0.3 V of V+ or V- without increasing linearity errors.
Care must be exercised to make sure the integrator out-
put does not saturate. In a typical application, the com-
mon mode is eliminated by connecting the INLO to COM,
Analog Common.
Differential Reference (VREF+ & VREF-)
the V+ to V-. Under a large common mode voltage, refer-
ence capacitor can gain charge during the de-integration
of a positive signal. The reference capacitor will lose
charge when de-integrating a negative input signal. The
difference in reference voltage for positive or negative in-
put voltages can cause the rollover error. To prevent rollover
error from being induced by large common-mode voltages,
reference capacitor should be large compared to stray
node capacitance.
The AME7106/AME7107 has true differential inputs and
The reference voltage can be generated anywhere within
High Accuracy, Low Power
3-1/2 Digit A/D Converter
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