Rainbow Electronics MAX98088 - Manual (Page 119)

Stereo Audio Codec
with FLEXSOUND Technology
MAX98088
119
Charge-Pump Flying Capacitor
The value of the flying capacitor (connected between
C1N and C1P) affects the output resistance of the
charge pump. A value that is too small degrades the
device’s ability to provide sufficient current drive, which
leads to a loss of output voltage. Increasing the value
of the flying capacitor reduces the charge-pump output
resistance to an extent. Above 1FF, the on-resistance
of the internal switches and the ESR of external charge-
pump capacitors dominate.
Charge-Pump Holding Capacitor
The holding capacitor (bypassing HPVSS) value and
ESR directly affect the ripple at HPVSS. Increasing
the capacitor’s value reduces output ripple. Likewise,
decreasing the ESR reduces both ripple and output
resistance. Lower capacitance values can be used in
systems with low maximum output power levels. See the
Output Power vs. Load Resistance graph in the Typical
Operating Characteristics section for more information
Unused Pins
Table 39 shows how to connect the IC's pins when
unused.
Table 39. Unused Pins
NAME CONNECTION NAME CONNECTION
SPKRP Unconnected INB1 Unconnected
SPKRVDD Always connected INA2/MICEXTN Unconnected
SPKLVDD Always connect LRCLKS2 Unconnected
SPKLP Unconnected MCLK Always connect
RECN/RXINN Unconnected SDINS2 AGND
HPVDD Unconnected IRQ Unconnected
C1P Unconnected MIC1P/DIGMICDATA Unconnected
HPGND AGND INA1/MICEXTP Unconnected
SPKRN Unconnected DGND Always connect
SPKRGND Always connect BCLKS2 Unconnected
SPKLGND Always connect SDA Always connect
SPKLN Unconnected SCL Always connect
RECP/RXINP Unconnected REG Always connect
C1N Unconnected REF Always connect
HPL Unconnected MIC1N/DIGMICCLK Unconnected
HPVSS Unconnected MIC2P Unconnected
SDINS1 AGND SDOUTS2 Unconnected
LRCLKS1 Unconnected DVDDS2 DVDD
HPSNS AGND DVDD Always connect
INB2 Unconnected AVDD Always connect
HPR Unconnected PVDD Always connect
DVDDS1 DVDD AGND Always connect
SDOUTS1 Unconnected MICBIAS Unconnected
BCLKS1 Unconnected MIC2N Unconnected
JACKSNS Unconnected