WM8978
Product Preview
ELECTRICAL CHARACTERISTICS
Test Conditions
DCVDD=1.8V, AVDD=DBVDD=SPKVDD = 3.3V, TA = +25oC, 1kHz signal, fs = 48kHz, 24-bit audio data unless otherwise
stated.
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Microphone Preamp Inputs (LIP, LIN, RIP, RIN, L2, R2)
Full-scale Input Signal Level –
VINFS
PGABOOST = 0dB
1.0
note this changes with AVDD
INPPGAVOL = 0dB
0
(Note 1)
Vrms
dBV
Mic PGA equivalent input noise
At 35.25dB
gain
TBD
uV
Input resistance
RMICIN
Gain set to 35.25dB
1.6
kΩ
RMICIN
Gain set to 0dB
47
kΩ
RMICIN
Gain set to -12dB
75
kΩ
RMICIP
MICP2INPPGA = 1
94
kΩ
RMICIP
MICP2INPPGA = 0
TBD
kΩ
Input Capacitance
CMICIN
10
pF
Recommended coupling cap
CCOUP
MIC Programmable Gain Amplifier (PGA)
220
pF
Programmable Gain
-12
35.25
dB
Programmable Gain Step Size
Guaranteed monotonic
0.75
dB
Mute Attenuation
TBD
dB
Selectable Input Gain Boost (0/+20dB)
Gain Boost on PGA input
Boost disabled
0
dB
Boost enabled
20
dB
Gain range from AUXL/R or
L/R2 input to boost/mixer
-12
+6
dB
Gain step size to boost/mixer
3
dB
Auxilliary Analogue Inputs (AUXL, AUXR)
Full-scale Input Signal Level
(0dB) – note this changes with
AVDD
VINFS
AVDD/3.3
0
Vrms
dBV
Input Resistance
RAUXINLMIN Left Input boost and mixer
4.3
kΩ
(Note 2)
enabled, at max gain
RAUXINLTYP Left Input boost and mixer
8.6
kΩ
enabled, at 0dB gain
RAUXINLMAX Left Input boost and mixer
39.1
kΩ
enabled, at min gain
RAUXINRMIN Right Input boost, mixer and
3
kΩ
beep enabled, at max gain
RAUXINRTYP Right Input boost, mixer and
6
kΩ
beep enabled, at 0dB gain
RAUXINRMAX Right Input boost, mixer and
29
kΩ
beep enabled, at min gain
Input Capacitance
CMICIN
10
pF
Automatic Level Control (ALC)
Target Record Level
Programmable gain
-28.5
-12
-6
dB
35.25
w
PP Rev 1.7 January 2005
6