19-3865; Rev 0; 10/05
MAX9705B Evaluation Kit
General Description
The MAX9705B evaluation kit (EV kit) is a fully assembled
and tested circuit board that uses the MAX9705B filter-
less Class D amplifier to drive a mono bridge-tied-load
(BTL) speaker in portable audio applications. Designed to
operate from a 2.5V to 5.5V DC power supply, the EV kit
is capable of delivering 2.3W into a 4Ω load.
The EV kit accepts differential or single-ended input
signals. The EV kit provides an option to select between
different switching frequency modes of operation. The
MAX9705B EV kit also evaluates the MAX9705A/
MAX9705C/MAX9705D.
Features
♦
Filterless Operation Passes FCC Radiated
Emissions
♦
Evaluates the MAX9705A/B/C/D (with IC
Replacement)
♦
2.5V to 5.5V Single-Supply Operation
♦
86% Efficiency
Drives 2.3W into 4Ω Speaker at 1% THD+N
Differential or Single-Ended Inputs
Selectable Switching Frequency
0.1µA Shutdown Current
Small 10-Pin TDFN Package
Also Available in 10-Pin
µMAX
®
and 12-Bump
UCSP™ Packages
♦
Fully Assembled and Tested
µMAX is a registered trademark and UCSP is a trademark of
Maxim Integrated Products, Inc.
Evaluates: MAX9705A/B/C/D
Ordering Information
PART
MAX9705BEVKIT
*EP
= Exposed paddle.
TEMP RANGE
0°C to +70°C
IC PACKAGE
10 TDFN-EP*
♦
♦
♦
♦
♦
♦
Component List
DESIGNATION
C1, C2
QTY
2
DESCRIPTION
0.1µF ±10%, 25V X7R ceramic
capacitors (0603)
TDK C1608X7R1E104K
1µF ±10%, 6.3V X5R ceramic
capacitors (0603)
TDK C1608X5R0J105K
MAX9705BETB (10-pin TDFN)
Not installed, MAX9705BEUB
(10-pin µMAX)
Not installed, MAX9705BEBC
(12-bump UCSP)
10µF ±20%, 6.3V X5R ceramic
capacitor (0603)
TDK C1608X5R0J106M
100pF ±5%, 50V C0G ceramic
capacitor (0603)
TDK C1608C0G1H101J
DESIGNATION
QTY
DESCRIPTION
OPTIONAL COMPONENTS FOR CUSTOMER EVALUATION
(continued)
C7–C11
JU1
JU2
JU3
L1, L2
OUT-, OUT+,
FOUT-, FOUT+
R1
R2, R3
—
—
0
1
1
1
0
0
1
0
3
1
Not installed, capacitors (0603)
3-pin header
5-pin header
2-pin header
Not installed, inductors
(TOKO D53LC Series)
Not installed, test points
49.9Ω ±1% resistor (0603)
Not installed, resistors (0603)
Shunts
MAX9705B EV kit board
C5, C6
U1
2
1
OPTIONAL COMPONENTS FOR CUSTOMER EVALUATION
A1
A2
0
0
C3*
1
*System-level
requirement.
C4
1
Component Suppliers
SUPPLIER
TDK
TOKO
PHONE
847-803-6100
847-297-0070
WEBSITE
www.component.tdk.com
www.tokoam.com
Note:
Indicate that you are using the MAX9705B when contact-
ing these component suppliers.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
MAX9705B Evaluation Kit
Evaluates: MAX9705A/B/C/D
Quick Start
The MAX9705B EV kit is fully assembled and tested.
Follow the steps listed below to verify board operation.
Do not turn on the power supply until all connec-
tions are completed.
The MAX9705B EV kit features PC board pads for filters
that can be added to ease evaluation. Audio analyzers
typically cannot accept pulse-width-modulated (PWM)
signals at their inputs. The PWM output signal can be
lowpass-filtered by installing components L1, L2,
C7–C11, R2, and R3. The filtered outputs should then
be monitored at the FOUT+/- test points. See Table 2
below for the suggested filtering components.
The MAX9705B is designed to pass FCC Class B RF
emissions without additional filtering when using up to
30cm of cable to connect the speaker. Table 1 lists the
cable length versus the required output components.
Recommended Equipment
• 2.5V to 5.5V, 1A power supply
• Audio source (i.e., CD player, cassette player)
• 8Ω speaker
Procedure
1) Install a shunt across pins 1 and 2 of jumper JU1
(EV kit ON).
2) Install a shunt across pins 1 and 2 of jumper JU2
(internal oscillator set to spread-spectrum mode).
3) Verify that no shunt is across jumper JU3 (differen-
tial input mode).
4) Connect the 8Ω speaker across the OUT+ and
OUT- test points.
5) Connect the positive terminal of the power supply to
the VDD pad and the power-supply ground terminal
to the GND pad.
6) Connect the audio source across the INPUT+ and
INPUT- pads.
7) Turn on the power supply.
8) Turn on the audio source.
Table 1. Cable Length vs. Suggested
Output Components
CABLE LENGTH X (cm)
X
≤
30
X > 30
LCR FILTER
L1, L2, C7–C11, R2, R3
—
Required
Table 2. Suggested Filtering Components
COMPONENT
C7, C8
VALUE
0.033µF ±10%, 25V X7R ceramic
capacitors (0603)
TDK C1608X7R1E333K
0.15µF ±10%, 25V X7R ceramic
capacitor (0603)
TDK C1608X7R1E154K
0.068µF ±10%, 25V X7R ceramic
capacitors (0603)
TDK C1608X7R1E683K
15µH ±20%, 1.4A inductors
TOKO A915AY-150M
22Ω ±5% resistors (0603)
Detailed Description
The MAX9705B EV kit features the MAX9705B filterless
Class D amplifier IC, designed to drive a BTL mono
speaker in portable audio applications. The EV kit oper-
ates from a DC power supply that can provide 2.5V to
5.5V and 1A of current. The EV kit accepts a differential
or single-ended audio input. The audio input source is
amplified to drive 2.3W into a 4Ω speaker.
The EV kit provides two sets of differential outputs. The
device outputs (OUT+/-) can be connected directly to a
speaker load, without any filtering, with up to 30cm of
cable. However, a filter can be added to ease evaluation.
C9
C10, C11
L1, L2
R2, R3
Output Filtering
The output (OUT+/-) can be connected directly to a
speaker load without any filtering. Use the OUT+/- test
points to connect the speakers directly to the EV kit out-
puts. This configuration is for a typical audio application.
2
_______________________________________________________________________________________
MAX9705B Evaluation Kit
Jumper Selection
Shutdown Mode
(SHDN)
Jumper JU1 controls the shutdown pin (SHDN) of the
MAX9705B IC. See Table 3 for shunt positions.
Input Mode
Jumper JU3 provides an option to select between a
differential or single-ended input mode for the EV kit.
See Table 5 for shunt positions.
Evaluates: MAX9705A/B/C/D
Table 3. JU1 Jumper Selection (SHDN)
SHUNT
POSITION
1-2 (default)
2-3
None (external
logic controller
connected to
SHDN
pad)
SHDN
PIN
High
Low
Connected
to external
controller
EV KIT FUNCTION
Enabled
Disabled
SHDN
driven by external
logic controller. Shutdown is
active low.
Table 5. JU3 Jumper Selection (Input Mode)
SHUNT POSITION
None
(default)
Installed
(INPUT- pad connected to
GND)
EV KIT INPUT MODE
Differential Input Mode
Single-Ended Input Mode
Switching Frequency Mode (SYNC)
Jumper JU2 provides an option to select the switching
frequency of the MAX9705B IC. See Table 4 for the
various shunt positions.
Evaluating the MAX9705A/MAX9705C/MAX9705D
The MAX9705B EV kit can evaluate the MAX9705A,
MAX9705C, and MAX9705D. To evaluate a different
IC, replace U1 with the desired part. Refer to the
MAX9705 IC data sheet for additional information.
Table 4. JU2 Jumper Selection (SYNC)
SHUNT
POSITION
1-2
(default)
1-3
SYNC PIN
INTERNAL
OSCILLATOR
FREQUENCY
Spread-Spectrum Mode.
Set at a switching
frequency f
SW
=
1.22MHz
±120kHz
Set at f
SW
= 1.45MHz
Synchronized to the
incoming TTL-compatible
clock frequency
Set at f
SW
= 1.1MHz
SYNC pin = high
SYNC pin = floating
SYNC pin = external
TTL-compatible clock
input. External clock
input connected to
SYNC (TTL).
SYNC = low
1-4
1-5
_______________________________________________________________________________________
3
MAX9705B Evaluation Kit
Evaluates: MAX9705A/B/C/D
VDD
1
C1
0.1µF
4
GND
U1
C5
1.0µF
AUDIO INPUT+
C6
1.0µF
AUDIO INPUT-
2
IN+
PGND
7
V
DD
PV
DD
10
C2
0.1µF
C3
10µF*
MAX9705B
OUT-
9
3
IN-
OUT+
8
MICROCONTROLLER
5
VDD
6
SHDN
SYNC
*SYSTEM-LEVEL REQUIREMENT
Figure 1. MAX9705B EV Kit Customer Design Schematic
VDD
1
C1
0.1µF
4
GND
PGND
7
R2
OPEN
U1
MAX9705B
IN-
OUT-
9
OUT-
OUT+
5
SHDN
OUT+
8
L1
OPEN
C7
OPEN
C11
OPEN
R3
OPEN
L2
OPEN
C10
OPEN
V
DD
PV
DD
10
C2
0.1µF
C3*
10µF
VDD
GND
INPUT+
C5
1.0µF
2 IN+
INPUT-
3
JU3
VDD
C6
1.0µF
C8
OPEN
C9
OPEN
SHDN
1 JU1
2
3
VDD
3 JU2
2
4
1
5
R1
49.9Ω
1%
C4
100pF
FOUT-
FOUT+
6
SYNC
SYNC
*SYSTEM-LEVEL REQUIREMENT
Figure 2. MAX9705B EV Kit Schematic
4
_______________________________________________________________________________________
MAX9705B Evaluation Kit
Evaluates: MAX9705A/B/C/D
Figure 3. MAX9705B EV Kit Component Placement Guide—
Component Side
Figure 4. MAX9705B EV Kit PC Board Layout—Component
Side
Figure 5. MAX9705B EV Kit PC Board Layout—GND Layer 2
Figure 6. MAX9705B EV Kit PC Board Layout—GND Layer 3
_______________________________________________________________________________________
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