max9727eept Maxim Integrated Products, Inc., max9727eept Datasheet - Page 11

• Manufacturer Part Number: max9727eept
• Description: Max9727 Quad Audio Line Driver With 3vrms Output
• Manufacturer: Maxim Integrated Products, Inc.

The value of the flying capacitor (C1) affects the load
regulation and the output resistance of the charge
pump. A C1 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 C1 improves the load regulation and reduces the
charge-pump output resistance to an extent. See the
Charge-Pump Output Voltage vs. Output Current
graphs in the Typical Operating Characteristics . Above
2.2µF, the on-resistance of the switches and the ESR of
C1 and C2 dominate.
The hold capacitor value and ESR directly affect the
ripple at PV
output ripple. Likewise, decreasing the ESR of C2
reduces both ripple and output resistance. Lower
capacitance values can be used in systems with low
maximum output voltage levels. See the Charge-Pump
Output Voltage vs. Output Current graphs in the Typical
Operating Characteristics . C2 should be greater than
or equal to the value of C1.
The PV
ance of the power supply and reduces the impact of
the MAX9727’s charge-pump switching transients.
Bypass PV
PV
the value of C1.
DD
and PGND. C3 should be greater than or equal to
DD
DD
bypass capacitor lowers the output imped-
Quad Audio Line Driver with 3V
SS
. Increasing the value of C2 reduces the
with C3 and place it physically close to
______________________________________________________________________________________
PV
DD
Bypass Capacitor (C3)
Flying Capacitor (C1)
Hold Capacitor (C2)
Proper power-supply bypassing ensures low-noise,
low-distortion performance. Connect a 1µF ceramic
capacitor from V
Good PC board layout is essential for optimizing perfor-
mance. Use large traces for the power-supply inputs
and amplifier outputs to minimize losses due to trace
resistance. Good grounding improves audio perfor-
mance, minimizes crosstalk between channels, and
prevents any digital switching noise from coupling into
the audio signal. Route PGND and all traces that carry
switching transients away from traces and components
in the audio signal path.
Place the charge-pump capacitors (C1 and C2) as
close to the device as possible. Connect V
together at capacitor C2.
Thermal-overload protection limits the total power dissi-
pation in the MAX9727. When the junction temperature
exceeds +160°C, the thermal protection circuitry dis-
ables the amplifier output stages. The junction temper-
ature must cool by 15°C before normal operation can
continue.
PROCESS: BiCMOS
DD
Thermal-Overload Protection
to PGND.
Layout and Grounding
RMS
Chip Information
Supply Bypassing
Output
SS
and PV
11
SS