CS5371A-ISZ(2006) View Datasheet(PDF) - Cirrus Logic
Part Name
Description
MFG CO.
CS5371A-ISZ Datasheet PDF : 32 Pages
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CS5371A CS5372A
VA+
VA+
OUTR+
CS3301A OUTF+
CS3302A
AMPLIFIER OUTF-
OUTR-
VA-
680
680
20nF
680
C0G
680
VA-
VA+
10 Ω
VREF
2.5 V
100µF
VA-
VA+
VA+
OUTR+
CS3301A OUTF+
CS3302A
AMPLIFIER OUTF-
OUTR-
VA-
VA-
680
680
20nF
680
C0G
680
VA+
VD
0.1µF
0.01µF
VD
VA+
INR+
INF+
20nF
C0G
INF-
INR-
VD
MDATA1
MFLAG1
PWDN1
MCLK
MSYNC
0.01µF
VREF+
CS5372A
∆Σ Modulator
VREF-
OFST
INR-
INF-
20nF
C0G
INF+
INR+
VA-
MDATA2
MFLAG2
PWDN2
GND
VA-
0.1µF
VDD2
MDATA1
MFLAG1
GPIO
MCLK
MSYNC
CS5376A
Digital Filter
GPIO
MDATA2
MFLAG2
GPIO
GND
Figure 11. Analog Signals
4. ANALOG SIGNALS
The CS5371A and CS5372A modulators have
differential analog inputs which are separated
into rough and fine charge differential pairs
(INR±, INF±) to maximize sampling accuracy.
Both sets of modulator inputs require a simple
differential anti-alias RC filter to ensure high-
frequency signals do not alias into the mea-
surement bandwidth.
4.1 INR±, INF± Modulator Inputs
The modulator analog inputs are separated
into differential rough and fine signals (INR±,
INF±). The positive half of the differential input
signal is connected to INR+ and INF+, while
the negative half is attached to INF- and INR-.
The INR± pins are switched-capacitor ‘rough
charge’ inputs that pre-charge the internal an-
alog sampling capacitor before it is connected
to the INF± fine input pins.
4.2 Input Impedance
The modulator inputs have a dynamic
switched-capacitor architecture and so have a
rough charge input impedance that is inversely
proportional to the input master clock frequen-
cy and the input capacitor size, [1 / (f x C)].
• MCLK = 2.048 MHz
• INR± Internal Input Capacitor = 20 pF
• Impedance = [1 / (2.048 MHz * 20 pF)] = 24 kΩ.
Internal to the modulator, the rough inputs
(INR±) pre-charge the sampling capacitor
used by the fine inputs (INF±), therefore the in-
put current to the fine inputs is typically very
low and the effective input impedance is or-
ders of magnitude above the impedance of the
rough inputs.
DS748F1
17
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