MAX9788EVKIT+ Maxim Integrated Products, MAX9788EVKIT+ Datasheet - Page 10

• Manufacturer Part Number: MAX9788EVKIT+
• Description: EVALUATION KIT FOR MAX9788
• Manufacturer: Maxim Integrated Products

Specifications of MAX9788EVKIT+

• Amplifier Type: Class G
• Output Type: 1-Channel (Mono)
• Max Output Power X Channels @ Load: 2.4W x 1 @ 8 Ohm
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Board Type: Fully Populated
• Utilized Ic / Part: MAX9788
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The output capacitor value and ESR directly affect the
ripple at PV
Likewise, decreasing the ESR of C2 reduces both rip-
ple and output resistance. A 10µF capacitor is recom-
mended.
The charge pump operates in two modes. When the
charge pump is loaded below 100mA, it operates in a
slow mode where the oscillation frequency is reduced to
1/4 of its normal operating frequency. Once loaded, the
charge-pump oscillation frequency returns to normal
operation. In applications where the design may be sen-
sitive to the operating charge-pump oscillation frequen-
cy, the value of the external resistor R
to adjust the charge-pump oscillation frequency shown
in Figure 4. A 100kΩ resistor is recommended.
A 1µF capacitor is a good model for the ceramic
speaker as it best approximates the impedance of a
ceramic speaker over the audio band. When selecting
a capacitor to simulate a ceramic speaker, the voltage
rating or the capacitor must be equal to or higher than
the expected output voltage swing. See Figure 5.
14V
Figure 4. Charge-Pump Oscillation Frequency vs. R
10
______________________________________________________________________________________
Charge-Pump Frequency Set Resistor (R
P-P
600
550
500
450
400
350
300
250
200
SS
. Increasing C2 reduces output ripple.
50
, Class G Ceramic Speaker Driver
Ceramic Speaker Impedance
CHARGE-PUMP OSCILLATION
75
FREQUENCY vs. R
R
FS
100
(kΩ)
Hold Capacitor (C2)
I
Characteristics
LOAD
FS
FS
125
> 100mA
can be changed
150
FS
FS
)
The capacitive nature of the ceramic speaker results in
very low impedances at high frequencies. To prevent
the ceramic speaker from shorting the MAX9788 output
at high frequencies, a series load resistor must be
used. The output load resistor and the ceramic speaker
create a lowpass filter. To set the rolloff frequency of
the output filter, the approximate capacitance of the
speaker must be known. This information can be
obtained from bench testing or from the ceramic
speaker manufacturer. A series load resistor greater
than 10Ω is recommended. Set the lowpass filter cutoff
frequency with the following equation:
For the latest application details on WLP construction,
dimensions, tape carrier information, PCB techniques,
bump-pad layout, and recommended reflow tempera-
ture profile, as well as the latest information on reliability
testing results, go to the Maxim website at www.maxim-
ic.com/ucsp for the application note, UCSP—A Wafer-
Level Chip-Scale Package .
Figure 5. Ceramic Speaker and Capacitor Impedance
WLP Applications Information
100k
100
10k
1M
1k
10
f
LP
0.001
=
2π
IMPEDANCE vs. FREQUENCY
0.01
×
CERAMIC
SPEAKER
R
L
FREQUENCY (Hz)
×
0.1
1
C
Series Load Resistor
SPEAKER
1μF CAPACITOR
1
( )
10
Hz
100