General Description
The MAX8654 evaluation kit (EV kit) is a fully assembled
and tested PCB that demonstrates the capabilities of
the MAX8654 integrated 8A step-down regulator. The
EV kit generates a 3.3V output voltage at load currents
up to 8A from a 4.5V to 14V input voltage range. The
MAX8654 switches at 500kHz and provides over 93.4%
efficiency with the supplied components.
Features
oInternal 26mΩRDS(ON) MOSFETs
oGuaranteed 8A Output Current
oAdjustable Over-Current Protection, 6A to 12A
o±1% Output Accuracy Over Load, Line, and
Temperature
oOperates from 4.5V to 14V Supply
oAdjustable Output from 0.6V to 0.85 x VIN
oSoft-Start Reduces Inrush Supply Current
o250kHz to 1.2MHz Adjustable Switching or SYNC
Input
oCompatible with Ceramic, Polymer, and
Electrolytic Output Capacitors
oSYNCOUT Synchronizes 2nd Regulator 180°
Out-of-Phase
o36-Pin 6mm x 6mm TQFN Package
Evaluates: MAX8654/MAX8688
MAX8654 Evaluation Kit
________________________________________________________________
Maxim Integrated Products
1
19-0643; Rev 1; 10/08
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.
Ordering Information
Component Suppliers
PART TEMP RANGE IC PACKAGE
MAX8654EVKIT+ 0°C to +70°C 36 TQFN
(6mm x 6mm)
SUPPLIER PHONE WEBSITE
M ur ata E l ectr oni cs
N orth Am er ica, Inc. 770-436- 1300 w ww .m ur ata- nor tham er ica.com
Taiyo Yuden 800-348- 2496 www.t-yuden.com
TDK Corp. 847-803- 6000 www.component.tdk.com
TOKO America, Inc. 847-297- 0070 www.tokoam.com
DESIGNATION QTY DESCRIPTION
C1A, C1B, C1C 3
10µF ±20%, 16V X5R ceramic
capacitors (1206)
Taiyo Yuden EMK316BJ106M
C2 1
1µF ±10%, 6.3V X5R ceramic
capacitor (0402)
Murata GRM155R60J105K
C3, C11 2
0.01µF ±10%, 50V X7R ceramic
capacitors (0402)
Murata GRM155R71H103K
C4 1
0.22µF ±20%, 16V X7R ceramic
capacitor (0603)
TDK C1608X7R1C224M
C5A, C5B, C5C 3
22µF ±20%, 6.3V X5R ceramic
capacitors (1206)
TDK C3216X5R0J226M
C6 1
6800pF ±10%, 50V X7R ceramic
capacitor (0402)
Murata GRM155R71H682KA88
C7 1
0.022µF, 10V X7R ceramic
capacitor (0402)
Murata GRM155R71C223CKA0I
Component Lists
DESIGNATION QTY DESCRIPTION
C8 1
1000pF, 50V C0G ceramic
capacitor (0402)
Murata GRM1555C1H1D2TADI
C9 1
4.7µF ±10%, 16V X5R ceramic
capacitor (0603)
Murata GRM21BR61C475K
C10 1
0.22µF,16V Y5R ceramic capacitor
(0402)
Taiyo Yuden EMK105BJ224MV-F
C12 1
470pF ±10%, 50V X7R ceramic
capacitor (0402)
Murata GRM155R71H471K
C13 1
0.1µF ±10%, 10V X7R ceramic
capacitor (0402)
Murata GRM155R61A104K
C14, C15 2
0.22µF ±20%, 50V X5R ceramic
capacitors (0805)
Taiyo Yuden UMK212BJ224M
C16 0
Not installed, 0.01µF ±10%, 25V X7R
ceramic capacitor (0402)
Murata GRM155R71E103K
+
Denotes a lead-free and RoHS-compliant EV kit.
Note: Indicate that you are using the MAX8654 when contact-
ing these component suppliers.
MAX8654 Circuit
Evaluates: MAX8654/MAX8688
Quick Start
Recommended Equipment
Before beginning, the following equipment is needed:
• Up to 12V at +3A DC power supply or battery
• Digital multimeter (DMM)
• Up to 8A load
• Ammeter (optional)
Procedure
The MAX8654 EV kit is fully assembled and tested.
Follow the steps below to verify board operation.
Caution: Do not turn on the power supply until all con-
nections are made.
1) Preset the DC power supply to 12V. Turn off the
power supply.
2) Ensure that there is a shunt on JU1 and JU2.
3) Ensure that there is a shunt on pins 1-2 of JU3.
4) Connect the positive lead of the power supply to the
VIN pad and connect the negative lead of the
power supply to the GND pad on the EV kit.
5) Connect the positive lead of the DMM to the VOUT
pad and connect the negative lead of the DMM to
the GND pad on the EV kit.
6) Turn on the power supply.
7) Verify that the voltage at VOUT is approximately
3.3V.
8) Connect the load between VOUT and GND.
9) Verify that the voltage at VOUT is approximately
3.3V.
MAX8654 Evaluation Kit
2 _______________________________________________________________________________________
Component Lists (continued)
DESIGNATION QTY DESCRIPTION
JP1–JP7,
JP9–JP13 0 Not installed
JU1, JU2, JU4 3 2-pin headers
JU3 1 3-pin header
L1 1
1µH, 7.9mΩ, 12A inductor (7.4mm x
6.7mm x 3mm)
TOKO FDV0630-1R0M
R1, R2, R10 3 100kΩ ±1% resistors (0402), lead free
R3 1 1.5kΩ ±1% resistor (0402), lead free
R4 1 332Ω ±1% resistor (0402), lead free
R5 1 15Ω ±5% resistor (0402), lead free
R6 1 475Ω ±1% resistor (0402), lead free
R7 1 75kΩ ±1% resistor (0402), lead free
R8 1 2.2Ω ±1% resistor (1206), lead free
R9, R11 2 1kΩ ±1% resistors (0402), lead free
R12 1 10Ω ±1% resistor (0402), lead free
U1 1 8A step-down regulator
Maxim MAX8654ETX+
— 3 Shunts
— 1 PCB: MAX8654 Evaluation Kit+
DESIGNATION QTY DESCRIPTION
C201, C202,
C203, C205,
C206, C207
0
100nF ±10%, 50V X7R ceramic
capacitors (0603), open
Murata GRM188R71H104K
C204 0
1µF ±10%, 10V X5R ceramic
capacitor (0603), open
Murata GRM188R61A105K
C208 0
2.2µF ±10%, 10V X5R ceramic
capacitor (0603), open
Taiyo Yuden LMK107BJ225K
C209 0 Ceramic capacitor, open
C210 0
0.47µF ±10%, 10V X5R ceramic
capacitor (0603), open
Murata GRM188R61A474K
D1 0
3.3V 350mW zener diode (SOT23),
open
Central Semiconductor CMPZ4620
JP201 0 4-pin header, open
JP202, JP203,
JP204 0 3-pin header, open
R19 0 100kΩ resistor, open
MAX8688 Circuit—Not Installed
MAX8654 Circuit
DESIGNATION QTY DESCRIPTION
R201, R204,
R206, R208,
R209, R214
0 Resistors, open
R202 0 0Ω resistor (0402)
R203 0 1kΩ ±1% resistor (0402), open
R205, R207,
R210 0 33kΩ ±1% resistors (0402), open
R211 0 909Ω ±5% resistor (0603), open
R213 0 100kΩ ±1% resistor (0402), open
R215 0 10kΩ ±1% resistor (0402), open
R216, R217 0 100Ω ±1% resistors (0402), open
U201 0 MAX8688+, open
U202 0 AT24C01A-10TSU-1.8, open
MAX8688 Circuit—Not Installed
Evaluates: MAX8654/MAX8688
MAX8654 Evaluation Kit
_______________________________________________________________________________________ 3
Detailed Description of Hardware
Evaluating Other Switching
Frequencies (FREQ)
The switching frequency in fixed-frequency PWM oper-
ation is resistor-programmable from 250kHz to 1.2MHz.
Set the switching frequency of the IC with a resistor
(RFREQ) from FREQ to GND. RFREQ is calculated as:
where fSis the desired switching frequency in megahertz.
Undervoltage Lockout (UVLO)
The UVLO circuitry inhibits switching when VIN or VVDL
is below 4.4V (VIN, VVDL rising) or VVL is below 3.1V
(VVL rising). Once these voltages are above the thresh-
olds, UVLO clears and the soft-start function activates.
A 100mV hysteresis is built in for glitch immunity.
Power Good (PWRGD)
PWRGD is an open-drain output that goes high imped-
ance once the soft-start ramp has concluded, provided
VFB and VREFIN are above 0.54V. PWRGD pulls low
when VFB falls below 0.54V for at least 50µs or VREFIN
is less than 0.54V. PWRGD is low during shutdown.
SYNC and SYNCOUT
The MAX8654 features a SYNC function that allows the
switching frequency to be synchronized to any external
clock frequency that is higher than the internal clock
frequency. Drive SYNC with a square wave at the
desired synchronization frequency. A rising edge on
SYNC triggers the internal SYNC circuitry. Connect
SYNC to GND to disable the function and operate with
the internal oscillator. The SYNCOUT output generates
a clock signal that is 180° out-of-phase with its internal
oscillator, or the signal applied to SYNC. This allows for
another MAX8654 to be synchronized 180° out-of-
phase to reduce the input ripple current.
Soft-Start and REFIN
The MAX8654 utilizes an adjustable soft-start function
to limit inrush current during startup. An 8µA (typ) cur-
rent source charges an external capacitor (C3) con-
nected to SS to increase the capacitor voltage in a con-
trolled manner. The soft-start time is adjusted by the
value of the external capacitor from SS to GND. The
required capacitance value is determined as:
where tSS is the required soft-start time in seconds.
The MAX8654 also features an external reference input
(REFIN). The IC regulates FB to the voltage applied to
REFIN. The internal soft-start is not available when
using an external reference. A method of soft-start
when using an external reference is shown in the
MAX8654 data sheet. Connect REFIN to SS to use the
internal 0.6V reference (jumper JU3).
Jumper Settings
Jumper JU1 Function
Drive EN high by placing a shunt on JU1 to turn on the
IC. To shut down the IC and reduce quiescent current
to 10µA (typ), remove the shunt on JU1. During shut-
down, the outputs of the MAX8654 are high impedance.
Jumper JU2 Function
Place a shunt on jumper JU2 to connect SYNC to GND.
Jumper JU3 Function
Place a shunt on pins 1-2 of JU3 to connect the REFIN
pin to the SS pin. When using an external reference,
place a shunt on pins 2-3 of jumper JU3.
Evaluating the MAX8688
The MAX8688 is a fully digital power-supply manager
that can be tested in conjunction with the MAX8654.
Samples of the MAX8688 IC can be ordered from
Maxim. To test the MAX8688, populate it with its circuit-
ry, as shown by the schematic or in the component list.
Also, place a shunt on pins 2-3 of JU3. For further infor-
mation, refer to the MAX8688 IC data sheet.
CAt
V
ss
=μ×8
06.
Rfsk
FREQ s
=×−μ
⎛
⎝
⎜
⎞
⎠
⎟Ω52 36 1005..
Evaluates: MAX8654/MAX8688
MAX8654 Evaluation Kit
4 _______________________________________________________________________________________4 _______________________________________________________________________________________
VDL
VIN
VIN
AGND
SYNC
SYNCOUT
PWRGD
REFIN
EN
ENABLE
VL
LX VOUT
REFIN
FB
VOUT
GND_SIGNAL
VIN
EN
VIN
VL
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18
19
20
21
22
23
24
25
26
27
28293031323334353637
PGND
PGND
PGND
VDL
IN
IN
IN
IN
VP
VL ILIM FREQ GND REFIN SS COMP FB PWRGD
SYNCOUT
SYNC
BST
LX
LX
LX
LX
LX
LX
LX
LX
N.C.
EN
GND
N.C.
PGND
PGNDPGND
EP
R9
1kΩ
C6
6800pF
C13
0.1μF
JP1
1
2
C5C
22μF
C9
4.7μF
JP13
1
2
JU1
1
2
C1A
10μF
JP6
1
2
C5A
22μF
C16
DNI
R12
10Ω
C2
1μF
C12
470pF
JU4
1
2
JU3
1
2
3
C4
0.22μF
R2
100kΩ
L1
1μH
C15
0.22μF
R10
100kΩ
JP2
1
2
JP10
1
2
R6
475Ω
R8
2.2Ω
C3
0.01μF
R3
1.5kΩ
1%
JP5
1
2
JP3
1
2
R4
332Ω
1%
JU2
1
2
C1C
10μF
C10
0.22μF
JP4
1
2
R1
100kΩ
1%
R7
75kΩ
1%
JP11
1
2
JP7
1
2
C5B
22μF
C7
0.022μF
C1B
10μF
JP12
1
2
C14
0.22μF
C8
1000pF
R5
15Ω
JP9
1
2
R11
1kΩ
C11
0.01μF
MAX8654
U1
Figure 1a. MAX8654 EV Kit Schematic (Sheet 1 of 2)
Evaluates: MAX8654/MAX8688
MAX8654 Evaluation Kit
_______________________________________________________________________________________ 5
1
2
3
1
2
3
1
2
3
1
2
3
PMBUS ADDRESS: 0x5A
OTP
CLKIN
SCL
ISN-
ISN+
SDA
SCL
SDA
FLT-
VOUT
REFIN
FB
V33
GND_SIGNAL
VIN
VOUT
LX
EN
V33
A1
V33
A3
A2
A1
A3
V33
V33
V33
V33
V33
VIN+
A2
V33
R217
100Ω
R210 33kΩ
R206 OPEN
R216
100Ω
R215
10kΩ
R213
100kΩ
D1
CMPZ4620
C202
100nF
C210
0.47μF
R19
100kΩ
TP4
C208
2.2μF
R207 33kΩ
TP3
TP6
C207
100nF
C203
100nF
R202
0Ω
C206
100nF
TP1
C205
100nF
JP203 R208 OPEN
C204
1μF
JP204
R201
OPEN
R214
OPEN
TP2
R205 33kΩ
C201
100nF
R211
909Ω
C209
OPEN
JP202
TP5
U201
1
2
3
4
5
6
78 9 10 11 12
13
14
15
16
17
18
1920212223
24
25
OTP1
DGND
DVDD
CLKIN
RST
SDA
SCL NC8 NC9 ENOUT FLT A3
A2
A1
DACOUT
AGND
AVDD
REFOUT
RSC
RS-
RS+
ISN-
ISN+
ISNC
EP
R204
OPEN
R209 OPEN
R203
1kΩ
U202
AT24C01A
1
2
3
4
5
SCL
VSS
SDA
VCC
WP
JP201
4
MAX8688
V33
RST
Figure 1b. MAX8654 EV Kit Schematic (Sheet 2 of 2)
Evaluates: MAX8654/MAX8688
MAX8654 Evaluation Kit
6 _______________________________________________________________________________________
Figure 2. MAX8654 EV Kit Component Placement Guide—Component Side
Evaluates: MAX8654/MAX8688
MAX8654 Evaluation Kit
_______________________________________________________________________________________ 7
Figure 3. MAX8654 EV Kit PCB Layout—Component Side
Evaluates: MAX8654/MAX8688
MAX8654 Evaluation Kit
8 _______________________________________________________________________________________
Figure 4. MAX8654 EV Kit PCB Layout—Inner Layer 1
Evaluates: MAX8654/MAX8688
MAX8654 Evaluation Kit
_______________________________________________________________________________________ 9
Figure 5. MAX8654 EV Kit PCB Layout—Inner Layer 2
Evaluates: MAX8654/MAX8688
MAX8654 Evaluation Kit
10 ______________________________________________________________________________________
Figure 6. MAX8654 EV Kit PCB Layout—Inner Layer 3
Evaluates: MAX8654/MAX8688
MAX8654 Evaluation Kit
______________________________________________________________________________________ 11
Figure 7. MAX8654 EV Kit PCB Layout—Inner Layer 4
Evaluates: MAX8654/MAX8688
MAX8654 Evaluation Kit
12 ______________________________________________________________________________________
Figure 8. MAX8654 EV Kit PCB Layout—Solder Side
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________
13
© 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
Evaluates: MAX8654/MAX8688
MAX8654 Evaluation Kit
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 5/07 Initial release —
1 10/08 Change in compensation components (C6, C7, C8, R5, and R6) 1, 2, 4
