MAX8792EVKIT [MAXIM]
300kHz Switching Frequency;
| 型号： | MAX8792EVKIT |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 300kHz Switching Frequency |
| 文件： | 总8页 (文件大小：190K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-0688; Rev 1; 1/10
MAX8792 Evaluation Kit
Evluates:MAX8792
General Description
Features
The MAX8792 evaluation kit (EV kit) demonstrates the
standard 10A application circuit of the MAX8792. This
DC-DC converter steps down high-voltage batteries to
generate low-voltage core or chipset/RAM bias
supplies in notebook computers.
o 7V to 24V Input Range
o Dynamically Selectable 1.5V/1.05V Output Voltage
o Dynamically Adjustable Output Voltage
(0 to V Range)
IN
The MAX8792 EV kit provides a dynamically adjustable
1.5V/1.05V output voltage from a 7V to 24V battery-
input range. It delivers up to 10A output current while
achieving greater than 90% efficiency. Programmed by
a single resistor, the EV kit operates at 300kHz switch-
ing frequency and has superior line- and load-transient
response.
o 10A Output Current
o 93% Efficiency (V = 7V, V
= 1.5V at 3A)
IN
OUT
o 300kHz Switching Frequency
o Power-Good Output Indicator (PGOOD)
o Low-Profile, Surface-Mount Components
o Fully Assembled and Tested
The EV kit is a fully assembled and tested PCB. It also
allows the evaluation of other dynamically adjustable
output voltages by varying the external reference input,
which can be realized by changing resistors R1, R2,
and R3.
Ordering Information
PART
TYPE
EV Kit
MAX8792EVKIT+
+Denotes lead(Pb)-free and RoHS compliant.
Component List
DESIGNATION
QTY
DESCRIPTION
DESIGNATION
QTY
DESCRIPTION
330µF, 2.0V, 6mΩ polymer
capacitors (D case)
1µF 10%, 6.3V X5R ceramic
capacitors (0402)
TDK C1005X5R0J105K
KEMET C0402C105K9PAC
C1, C2
2
Panasonic EEFSX0D331XR
(6mΩ ESR, 1.9mm height)
NEC/TOKIN PSGD0E337M7
(7mΩ ESR, 2.8mm height)
C10, C11
2
1000pF 10%, 50V ceramic
capacitor (0402)
KEMET C0402C102K5RAC
TDK C1005X7R1H102K
10µF 20%, 6.3V X5R ceramic
capacitor (0805)
TDK C2012X5R0J106M
KEMET C0805C106K9PAC
C3
1
C12
1
10µF 20%, 25V X5R ceramic
capacitors (1210)
TDK C3225X7R1E106M
Taiyo Yuden TMK325BJ106MM
2A, 30V Schottky diode (SMA)
Nihon EC21QS03L
Central Semiconductor CMSH2-40M
C4, C5
C6
2
0
1
0
D1
D2
1
1
Green surface-mount LED (0805)
Lite-ON LTST-C170GKT
Digi-Key 160-1179-1-ND
Not installed, capacitor
0.1µF 10%, 25V X7R ceramic
capacitor (0603)
TDK C1608X7R1E104K
Murata GRM188R71E104K
C7
EN, GATE,
PGOOD, REFIN,
SKIP
Test points
Keystone 5000
5
C8, C9, C13
Not installed, capacitors (0603)
JU1
JU2
JU3
1
1
1
3-pin header
2-pin header
4-pin header
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX8792 Evaluation Kit
Component List (continued)
Component Suppliers
DESIGNATION
QTY
DESCRIPTION
1.0µH, 3.25mΩ, 16A power
inductor
SUPPLIER
Central
Semiconductor
Corp.
PHONE
WEBSITE
L1
1
631-435-1110 www.centralsemi.com
805-446-4800 www.diodes.com
Würth 744 355 2100
30V n-channel MOSFET
Diodes
Incorporated
®
(PowerPAK 8-pin SO)
N1
N2
1
1
Fairchild FDMS8690
Vishay/Siliconix SI7634DP
Fairchild
Semiconductor
888-522-5372 www.fairchildsemi.com
864-963-6300 www.kemet.com
30V n-channel MOSFET
(PowerPAK 8-pin SO)
Fairchild FDS8670
KEMET Corp.
Murata Electronics
North America, Inc.
www.murata-
770-436-1300
northamerica.com
Vishay/Siliconix SI7336ADP
NEC TOKIN
America, Inc.
408-324-1790 www.nec-tokin.com
n-channel logic-level MOSFET
(SOT23)
Nihon Inter
Electronics Corp.
N3
1
Fairchild 2N7002 (Top Mark: 702)
Diodes Inc. ZVN3306F
(Top Mark: MC)
847-843-7500 www.niec.co.jp
800-344-2112 www.panasonic.com
619-661-6835 www.sanyo.com
Evluates:MAX8792
Panasonic Corp.
N4
R1, R11
R2
0
2
1
1
1
0
1
Not installed
SANYO Electric
Co., Ltd.
49.9kΩ 1% resistors (0603)
54.9kΩ 1% resistor (0603)
97.6kΩ 1% resistor (0603)
1kΩ 5% resistor (0603)
Not installed, resistor (0402)
200kΩ 1% resistor (0603)
Note: Indicate that you are using the MAX8792 when contacting
these component suppliers.
R3
R4
Quick Start
Recommended Equipment
R5
R6
•
7V to 24V power supply, battery, or notebook AC
adapter
Not installed, resistors
(short PC trace) (0603)
R7, R13
0
•
•
•
•
DC bias power supply, 5V at 100mA
Dummy load capable of sinking 10A
Digital multimeter (DMM)
R8, R10
R9
0
1
1
1
Not installed, resistors (0603)
0Ω 5% resistor (0603)
R12
100kΩ 1% resistor (0603)
100kΩ 5% resistor (0603)
100MHz dual-trace oscilloscope
R14
PWM controller (14 TDFN-EP*)
Maxim MAX8792ETD+
U1
1
—
3
1
Shunts
—
PCB: MAX8792 EVALUATION KIT+
*EP = Exposed pad.
PowerPAK is a registered trademark of Vishay Siliconix.
2
_______________________________________________________________________________________
MAX8792 Evaluation Kit
Evluates:MAX8792
Procedure
The MAX8792 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
connections are completed:
Table 1. Jumper JU1 Functions
SHUNT
POSITION
MAX8792
OUTPUT
EN PIN
Enabled
(V = 1.5V/1.05V)
1-2*
2-3
Connected to VDD
Connected to GND
OUT
Shutdown mode
(V = 0V)
1) Ensure that the circuit is connected correctly to the
supplies and dummy load prior to applying any
power.
OUT
2) Verify that the shunts are across JU1 pins 1-2
(EN high), JU2 pins uninstalled (1.5V output), and
JU3 pins 1-2 (forced PWM).
EN must be driven by
an external signal
connected to the EN
test point
Operation depends
on the external EN
signal levels
Not installed
3) Turn on battery power prior to +5V bias power;
otherwise, the output undervoltage (UVP) FAULT
latch will be set, disabling the regulator until +5V
power is cycled below 0.5V or EN is toggled.
*Default position.
Table 2. Jumper JU2 Functions
4) Observe the 1.5V output with the DMM and/or oscillo-
scope. Look at the LX switching node and MOSFET
gate-drive signals while varying the load current.
SHUNT
MAX8792
EXTERNAL GATE
POSITION
OUTPUT
A logic-high on GATE
turns on the external
MOSFET, effectively
Detailed Description of Hardware
Jumper Settings
Several jumper settings in the following tables illustrate
some features of the MAX8792 EV kit.
Installed
Connected to VDD
shorting R3 (V
=
OUT
1.05V through resistor-
dividers R1 and R2).
Shutdown Control Input
The MAX8792 EV kit features a 3-pin jumper (JU1) that
selects the shutdown control input. Table 1 lists the
selectable jumper options.
A logic-low on GATE turns
off the external MOSFET
Not
installed*
Pulled to GND by
R14
(V
OUT
= 1.5V through
resistor-dividers R1 and
R2 + R3).
External Gate
The MAX8792 EV kit features a 2-pin jumper (JU2) that
controls the gate of the external MOSFET (N3). The
external MOSFET can be controlled through the GATE
test point to dynamically adjust the REFIN voltage by
forcing N3 to a low- or a high-impedance state. The
default configuration has a shunt installed on only one
pin of JU2 to provide a 1.5V output. Table 2 lists the
selectable jumper options.
*Default position.
Table 3. Jumper JU3 Functions
SHUNT
OPERATIONAL
SKIP PIN
POSITION
MODE
Low-noise mode,
forced-PWM operation
1-2*
1-3
Connected to VDD
Pulse-Skipping Control Input
The MAX8792 EV kit features a 4-pin jumper (JU3) for
pulse-skipping control input. This four-level input deter-
mines the mode of operation under normal steady-state
conditions and dynamic output-voltage transitions. The
default configuration has a shunt installed at pins 1-2
for low-noise forced-PWM mode. Table 3 lists the other
selectable jumper options. Refer to the Modes of
Operation section of the IC data sheet for a more
detailed description.
Pulse-skipping mode
with forced-PWM during
transitions
Connected to REF
Pulse-skipping mode
Connected to GND without forced-PWM
during transitions
1-4
Ultrasonic mode without
forced-PWM during
transitions
Not installed
Open
*Default position.
_______________________________________________________________________________________
3
MAX8792 Evaluation Kit
Evaluating Other Dynamic Output Voltages
The EV kit output is preset to 1.05V/1.5V. However, the
output voltage can also be adjusted between 0 and 2V
(FB = OUT) by selecting R1, R2, and R3 values. The
MAX8792 regulates FB to the voltage set at REFIN. By
changing the voltage at REFIN, the MAX8792 can be
used in applications that require dynamic output volt-
age changes between two set points. Using the exter-
nal GATE signal, a resistor can be switched in and out
of the REFIN resistor-divider, changing the voltage at
REFIN. A logic-high on GATE turns on the external
n-channel MOSFET, forcing N3’s drain to a low-imped-
ance state. A logic-low on GATE disables the n-channel
MOSFET, so N3’s drain is high impedance. The two
output voltages (FB = OUT) are determined by the fol-
lowing equations:
Setting V with a
OUT
Resistive Voltage-Divider at FB
Connecting FB to a resistive voltage-divider allows
for output voltages above the reference voltage (0 to
0.9 x V range). To get an output above 2V, install
IN
resistor R10 with a 10kΩ 1% resistor and replace R9
with the following equation:
R9
R10
⎛
⎝
⎞
V
= V 1+
⎜
FB
⎟
⎠
OUT
where V = V
.
FB
REFIN
The switching-frequency setting input should then be
adjusted by replacing the external resistor R6 (R
according to the following equations:
)
TON
⎛
⎞
V
FB
T
= C
R
+ 6.5kΩ
⎜
(
)
V
⎝
R2
R1+ R2
⎛
⎞
SW
TON TON
⎟
V
=
=
V
REF
⎠
⎜
⎝
⎟
⎠
OUT
OUT(LOW)
1
T
=
R2 + R3
R1+ R2 + R3
⎛
⎞
Evluates:MAX8792
SW
f
V
V
REF
⎜
⎟
⎠
SW
OUT(HIGH)
⎝
where C
= 16.26pF, f
= 300kHz, and V = V
SW FB REFIN
TON
under normal operating conditions. Refer to the
MAX8792 data sheet for selection of output capacitor
and inductor values for output voltages greater than 2V.
where V
= 2.0V.
REF
4
_______________________________________________________________________________________
MAX8792 Evaluation Kit
Evluates:MAX8792
Figure 1. MAX8792 EV Kit Schematic
_______________________________________________________________________________________
5
MAX8792 Evaluation Kit
Figure 2. MAX8792 EV Kit Component Placement Guide—
Component Side
Figure 3. MAX8792 EV Kit PCB Layout—Component Side
Evluates:MAX8792
Figure 4. MAX8792 EV Kit PCB Layout—GND Layer 2
6
_______________________________________________________________________________________
MAX8792 Evaluation Kit
Evluates:MAX8792
Figure 5. MAX8792 EV Kit PCB Layout—GND Layer 3
Figure 6. MAX8792 EV Kit PCB Layout—Solder Side
Figure 7. MAX8792 EV Kit Component Placement Guide—
Solder Side
_______________________________________________________________________________________
7
MAX8792 Evaluation Kit
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
DESCRIPTION
0
1
4/07
1/10
Initial release
—
4
Correction made in the Setting V
section
with a Resistive Voltage-Divider at FB
OUT
Evluates:MAX8792
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.
8
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© 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
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