General Description
The MAX8556 evaluation kit (EV kit) is a fully assembled
and tested surface-mount circuit board demonstrating
the MAX8556 low-dropout (LDO) regulator. The EV kit
comes assembled with a MAX8556ETE circuit that
steps down a 1.425V to 3.6V input voltage range to a
1.2V output capable of sourcing up to 4A (limited by
power dissipation). The MAX8556 features a POK out-
put that goes high impedance once the output is within
±10% of its regulation value. The device utilizes an
internal p-channel MOSFET for reduced dropout and
quiescent current. In addition, the p-channel MOSFET
eliminates the need for an external bias or noisy charge
pump. The MAX8556 EV kit can also be used to evalu-
ate the MAX8557 with no component changes.
Features
♦1.425V to 3.6V Input Voltage Range
♦1.2V Output Voltage
♦Up to 4A Output Current
♦Low Dropout Voltage (200mV max at 4A)
♦Internal p-Channel MOSFET Pass Transistor
♦Power-OK (POK) Output
♦Fully Assembled and Tested
Evaluates: MAX8556/MAX8557
MAX8556 Evaluation Kit
________________________________________________________________ Maxim Integrated Products 1
19-3393; Rev 0; 8/04
Component List
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
PART
TEMP RANGE
IC PACKAGE
MAX8556EVKIT
0°C to +70°C
16 Thin QFN 5mm x 5mm
DESIGNATION QTY DESCRIPTION
C1–C4 4 10µF ±20%, 6.3V X5R ceramic
capacitors (0805)
Taiyo Yuden JMK212BJ106MG
JU1 1 3-pin header
Sullins PTC36SAAN
R1 1 100kΩ ±5% resistor (0603)
R2 1 1.40kΩ ±0.1% resistor (0603)
Vishay TNPW06031401BT9RT1
R3 1 1kΩ ±0.1% resistor (0603)
Panasonic ERA3YEB102V
U1 1 MAX8556ETE (16-pin Thin QFN)
None 1 Shunt
None 1 MAX8556EVKIT PC board
Note: To evaluate the MAX8557, request a MAX8557ETE free
sample with the MAX8556 EV kit.
Component Suppliers
SUPPLIER COMPONENT PHONE WEBSITE
Panasonic Resistors 714-373-7366 www.maco.panasonic.co.jp
Taiyo Yuden Capacitors 408-573-4150 www.t-yuden.com
Vishay Resistors 402-563-6866 www.vishay.com
Note: Indicate that you are using the MAX8556/MAX8557 when contacting these component suppliers.
Evaluates: MAX8556/MAX8557
MAX8556 Evaluation Kit
2_______________________________________________________________________________________
Recommended Equipment
•One 4V, 5A variable-output power supply
•Dummy load capable of sinking 4A
•Digital multimeter (DMM)
Quick Start
The MAX8556 EV kit is fully assembled and tested.
Follow these steps to verify board operation:
1) Preset the power supply to 1.425V and turn off the
power supply. Do not turn on the power supply
until all connections are made.
2) Verify that the shunt is across pins 2 and 3 of JU1 to
enable the device.
3) Connect the positive lead of the power supply to the
VIN pad on the EV kit, and the negative lead of the
power supply to the GND pad on the EV kit.
4) Connect the positive input of the DMM to the VOUT
pad on the EV kit, and the negative input of the
DMM to the GND pad on the EV kit to measure the
output voltage.
5) Turn on the power supply and verify that the output
voltage is 1.2V ±1%.
6) Sweep the input voltage from +1.425V to +3.6V.
Verify that the output voltage is 1.2V ±1% over the
entire input range.
7) Set the power supply to 2V.
8) Connect the 4A load between the VOUT and GND
pads on the EV kit.
9) Verify that the output voltage is 1.2V ±1%.
Detailed Description
Adjusting the Output Voltage
R2 and R3 are used to adjust the output voltage for the
MAX8556. To adjust the output voltage, replace R2 with
a 0.1% resistor that is calculated as:
R2 = 1 x 103x ((VOUT / VFB) - 1)
where VFB is 0.5V and VOUT is the desired output voltage.
POK Output
The MAX8556 has an open-drain POK output that goes
high impedance after the output is within ±10% of the
regulation voltage. On the EV kit, R1 pulls up POK to
VIN. The MAX8556 EV kit can also be used to evaluate
the MAX8557. In this case, the POK output becomes
the POR output.
Shutdown
The MAX8556 features a shutdown mode to power
down the output and reduce input current. To shut
down the device, place the shunt between positions 1
and 2 of JU1. To operate normally, place the shunt
between positions 2 and 3 of JU1.
Jumper Settings
SHUNT
LOCATION
EN CONNECTION OPERATION
1 and 2 Connected to GND Output disabled
2 and 3 Connected to VIN Output enabled
Table 1. Jumper JU1 Functions (EN)
Evaluates: MAX8556/MAX8557
MAX8556 Evaluation Kit
_______________________________________________________________________________________ 3
JU1 1
2
316
12
R1
100kΩ
C2
10µF
C1
10µF
VIN
1.425V TO 3.6V
GND
POK
IN
POK
EN N.C. GND
FB
OUT
R2
1.4kΩ
0.1%
R3
1.0kΩ
0.1%
14
13
C3
10µFGND
C4
10µF
VOUT
1.2V AT 4A
7, 8, 9, 10, 11
1, 2, 3, 4, 5, 6
MAX8556ETE
U1
15
Figure 1. MAX8556 EV Kit Schematic
Figure 2. MAX8556 EV Kit Component Placement Guide—Top
Silkscreen Figure 3. MAX8556 EV Kit PC Board Layout—Component 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
©2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Evaluates: MAX8556/MAX8557
MAX8556 Evaluation Kit
Figure 4. MAX8556 EV Kit PC Board Layout—Layer 2 Figure 5. MAX8556 EV Kit PC Board Layout—Layer 3
Figure 6. MAX8556 EV Kit PC Board Layout—Solder Side
