MAX8815AEVKIT+ [MAXIM]
Guaranteed 1A Output Current at 5V from 2.5V Input;
| 型号： | MAX8815AEVKIT+ |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Guaranteed 1A Output Current at 5V from 2.5V Input |
| 文件： | 总4页 (文件大小：87K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-4216; Rev 0; 7/08
MAX8815A Evaluation Kit
Evluates:MX815A
General Description
Features
o Up to 97% Efficiency with Internal Synchronous
The MAX8815A evaluation kit (EV kit) is a fully assem-
bled and tested printed-circuit board (PCB) for evaluat-
ing the MAX8815A step-up converter. The MAX8815A
is a 1A (maximum load), 97% efficient, 35µA quiescent
current step-up converter with True Shutdown™ and is
ideal for use in DSC, DVC, and other handheld appli-
cations. The MAX8815A EV kit is designed for a 5V
output and also provides a jumper for evaluation of
fixed-frequency pulse-width-modulation mode (FPWM)
or normal mode.
Rectifier
o Low 35µA (Switching) Quiescent Current
o Guaranteed 1A Output Current at 5V from 2.5V Input
o Guaranteed 500mA Output Current at 5V from 1.8V
Input
o Low-Noise Constant Frequency Operation (FPWM
Mode)
o 2MHz PWM Switching Frequency
o Preset (5V) or Adjustable Output (3.3V to 5V)
o Controlled Current in Soft-Start Limits Inrush
Current
o True Shutdown
True Shutdown is a trademark of Maxim Integrated Products, Inc.
o Internal Compensation
o Overload/Short-Circuit Protection
o 0.1µA Shutdown Current
o Lead-Free and RoHS Compliant
o Fully Assembled and Tested
Component Suppliers
SUPPLIER
NEC TOKIN
PHONE
WEBSITE
408-324-1790 www.nec-tokinamerica.com
America, Inc.
Ordering Information
Sullins Electronics Corp. 760-744-0125 www.sullinselectronics.com
PART
TYPE
Taiyo Yuden
TOKO
408-573-4150 www.t-yuden.com
847-297-0070 www.toko.com
MAX8815AEVKIT+
EV Kit
Note: Indicate that you are using the MAX8815A when contact-
+Denotes lead-free and RoHS compliant.
ing these component suppliers.
Component List
DESIGNATION
QTY
DESCRIPTION
DESIGNATION
QTY
DESCRIPTION
1.2µH inductor
C1A
0
Not installed, capacitor
L1
1
TOKO A1124BS-1R2 (DE4512CK
Series)
10µF 10%, 6.3V X5R ceramic
capacitor (0805)
C1B
1
R1
R2
R3
0
0
1
PCB short, resistor (0402)
Not installed, resistor (0402)
100Ω 1% resistor (0402)
Taiyo Yuden JMK212BJ106KG, or
equivalent
C2A
C2B
0
1
Not installed, capacitor
22µF/10V, 70mΩ ESR tantalum
capacitor
NEC Tokin PSLB31A226M
MAX8815AETB+ (10 TDFN-EP,
3mm x 3mm)
U1
—
1
1
PCB: MAX8815A Evaluation Kit+
0.1µF 20%, 10V X5R ceramic
capacitor (0402)
Taiyo Yuden LMK105BJ104MV
C3
1
2
3-pin headers
1 x 36-pin headers, 0.1in centers
(comes in 1 x 36-pin strips, cut to fit)
Sullins PEC36SAAN
JU1, JU2
Digi-Key S1012E-36-ND
________________________________________________________________ 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.
MAX8815A Evaluation Kit
Normal Mode
Drive SKIPB low to select the normal mode of opera-
tion. In this mode, the device operates in PWM only
when driving medium to heavy loads. As the load cur-
rent decreases and crosses the low-power idle-mode
threshold, the PWM comparator and oscillator are dis-
abled. In this low-power mode, switching occurs only
as needed to service the output. This improves the effi-
ciency for light loads, and the device consumes only
35µA under no-load conditions. The threshold for enter-
ing skip mode is approximately 90mA load with a 3.6V
input and 5V output. When switching in normal mode,
the inductor current terminates at zero for each switch-
ing cycle.
Quick Start
Recommended Equipment
A 1.2V to 5.5V power supply capable of delivering
2.5A
•
•
•
•
One voltmeter (DMM)
Load capable of sinking 1A
Ammeter (optional)
Procedure
The MAX8815A EV kit is fully assembled and tested.
Follow the steps below to verify board operation.
1) Preset the power supply to 3.6V.
2) Turn off the power supply. Do not turn on the
FPWM Mode
Drive SKIPB high to select the FPWM mode of opera-
tion. The IC switches at a constant frequency (2MHz)
and modulates the MOSFET switch pulse width
to control the power transferred per cycle to regulate
the output voltage. Switching harmonics gene-
rated by fixed-frequency operation are consistent
and easily filtered. This is important in noise-sensitive
applications.
power supply until all connections are completed.
3) Verify that the shunt on JU1 is connected to OFF
(pins 2 and 3). Verify that the shunt on JU2 is con-
nected to NORM (pins 2 and 3).
4) Connect the positive power-supply terminal to the
pad on the EV kit labeled IN. Connect the power-
supply ground terminal to the pad on the EV kit
labeled GND.
Evluates:MX815A
The MAX8815A does not allow for dynamic switching
between normal and FPWM modes.
5) Connect a voltmeter across the OUT pad on the EV
kit and the GND pad on the EV kit.
6) Connect the 1A load between OUT and GND with
the load set to minimum.
Shutdown Mode
Connect ON to GND or connect a shunt to pins 2 and 3
of JU1 to place the MAX8815A in shutdown mode and
reduce supply current to 0.1µA. In shutdown, the
control circuitry, internal switching MOSFET, and
synchronous rectifier turn off and LX becomes high
impedance. Connect ON to IN or connect a shunt to
pins 1 and 2 of JU1 for normal operation.
7) Turn on the power supply.
8) Verify that the voltmeter is reading 0V and input
current is less than 1µA.
9) Remove the shunt from the OFF position (pins 2
and 3) of JU1 and place it on the ON position (pins
1 and 2) of JU1.
Evaluating Other Output Voltages
The MAX8815A EV kit is designed for the preset output
voltage of 5V. To set other output voltages, use external
feedback resistors.
10) Verify the voltmeter is measuring between 4.95V
and 5.05V.
11) Slowly increase the load up to 1A and verify the
output voltage.
To set the output voltage between 3.3V and 5V, cut the
PCB short on resistor R1, and connect FB to the center
of an external resistor voltage-divider between OUT
and GND, as shown in Figure 2. Select the value of R2
no more than 500kΩ, and then calculate the value for
R1 as follows:
Detailed Description
Normal and FPWM Mode
The MAX8815A operates in two modes, normal mode
and FPWM mode, depending on the voltage at SKIPB.
SKIPB is assigned to pin 2 on jumper JU2. Connecting
a shunt to pins 2 and 3 of JU2 sets the IC to normal
operation. Connecting a shunt to pins 1 and 2 sets the
IC to FPWM mode only.
R1 = R2 (V /V - 1)
OUT FB
where V is the FB regulation voltage, 1.265V (typ).
FB
2
_______________________________________________________________________________________
MAX8815A Evaluation Kit
Evluates:MX815A
L1
1.2µH
1.2V TO 5.5V
3
1, 2
LX
IN
BATT
5V, UP TO 1A
9, 10
C1B
OUT
GND
POUT
GND
C2B
R3
100Ω
U1
IN
7
OUTS
MAX8815A
1
2
C3
0.1µF
4
8
ON
ON
3
IN
JU1
6
5
FB
1
2
3
SKIPB
GND
EP
JU2
Figure 1. MAX8815A EV Kit Schematic—Fixed 5V Output
L1
1.2µH
1.2V TO 5.5V
3
1, 2
IN
LX
BATT
5V, UP TO 1A
C2B
C1B
9, 10
OUT
GND
POUT
GND
R3
100Ω
U1
IN
7
OUTS
MAX8815A
1
2
C3
0.1µF
4
8
ON
ON
R1
R2
3
IN
JU1
6
5
FB
1
2
3
SKIPB
GND
EP
JU2
Figure 2. MAX8815A EV Kit—Adjustable Output Voltage
_______________________________________________________________________________________
3
MAX8815A Evaluation Kit
Figure 3. MAX8815A EV Kit Component Placement Guide—
Component Side
Figure 4. MAX8815A EV Kit PCB Layout—Component Side
Evluates:MX815A
Figure 5. MAX8815A 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.
4 ___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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