MAX8989 Evaluation Kit
Evaluates: MAX8989
General Description
The MAX8989 evaluation kit (EV kit) is a fully assembled
and tested circuit for evaluating the MAX8989 step-down
converter with linear bypass regulator. The EV kit oper-
ates from a 2.7V to 5.5V power supply or battery. The
output regulates to twice the voltage at REFIN (0.2V to
1.7V) and provides up to 2.5A drive capability.
S
PA Step-Down Converter
Features
25µs (typ) Settling Time for 0.4V to 3.2V Output-
Voltage Change
Dynamic Output-Voltage Setting from 0.4V to
V
IN
85mI PFET and 100% Duty Cycle for Low
Dropout
2MHz Switching Frequency
Low Output-Voltage Ripple
2% Output-Voltage Accuracy Over Load, Line,
and Temperature
Tiny External Components
S
2.5A Output-Current Capability
S
Simple Logic On/Off Control
S
Low 0.1µA Shutdown Current
S
2.7V to 5.5V Supply Voltage Range
S
Thermal-Overload Protection
S
Proven PCB Layout
S
Fully Assembled and Tested
Component List
DESIGNATION
C1, C2, C4, C5,
C6
QTY
5
DESCRIPTION
4.7FF 20%, 6.3V X5R ceramic
capacitors (0603)
TDK C1608X5R0J475M
1000pF
Q5%,
50V C0G ceramic
capacitor (0402)
Murata GRM1555C1H102J
Not installed, ceramic capacitor
(0603)
2-pin header, 0.1in
3-pin header, 0.1in
4.7FH
Q20%,
252mI,
850mA inductor, 1.2mm (max)
height (2520)
TOKO 1239AS-H-4R7N=P2
(DFE252012C)
PWM step-down converter
(9 WLP, 0.5mm pitch)
Maxim MAX8989EWL+
Shunts, 2-position
PCB: MAX8989 EVALUATION
KIT+
C3
1
C7
JU1
JU2
0
1
1
L1
1
Ordering Information
PART
MAX8989EVKIT+
TYPE
EV Kit
U1
—
—
1
2
1
+Denotes
lead(Pb)-free and RoHS compliant.
Component Suppliers
SUPPLIER
Murata Electronics North America, Inc.
TDK Corp.
TOKO America, Inc.
PHONE
770-436-1300
847-803-6100
847-297-0070
WEBSITE
www.murata-northamerica.com
www.component.tdk.com
www.tokoam.com
Note:
Indicate that you are using the MAX8989 when contacting these component suppliers.
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-5745; Rev 0; 1/11
MAX8989 Evaluation Kit
Evaluates: MAX8989
Quick Start
•
•
•
MAX8989 EV kit
10) Turn on the power supply and voltage reference.
11) Install the shunt on jumper JU1.
12) With the voltmeter, verify that the voltage from OUT to
PGND2 is approximately twice the reference voltage.
Recommended Equipment
2.7V to 5.5V power supply or battery capable of
delivering 2.5A
Voltage reference or power supply capable of
providing 0.2V to 1.7V (must be able to sink and
source up to 1mA)
Voltmeter
Load (resistor or electronic load)
Detailed Description of Hardware
The MAX8989 output regulates to twice the voltage at
REFIN and provides up to 2.5A drive capability. REFIN
must connect to an external reference supply between
0.2V and 1.7V. Connect the ground of the reference
supply to the AGND PCB pad.
Do not use AGND as a
power-ground connection.
Enable/shutdown control is provided by jumper JU1. For
normal operation, place a shunt on the pins of JU1. For
low-power shutdown mode, remove the shunt from JU1.
In shutdown mode, the step-down regulator and LDO are
off, reducing the supply current to 0.1µA (typ).
To drive the enable input from an external logic source,
remove the shunt on JU1. Connect the logic signal to pin
2 of JU1. Connect the signal ground to AGND. Refer to
the
Electrical Characteristics
section in the MAX8989 IC
data sheet for the required logic levels.
The device has an optional skip mode. To enable skip
mode, connect pins 2-3 of jumper JU2. Skip mode pro-
vides the highest possible efficiency during light-load
conditions, reducing the no-load supply current to 115µA
(typ). Skip mode is only active when the output voltage is
less than 1V.
To prevent the device from entering skip mode, connect
pins 1-2 of JU2.
•
•
The EV kit is fully assembled and tested. Follow the steps
below to verify board operation:
1)
2)
3)
Preset the power supply to 3.7V.
Procedure
Enable
Preset the voltage reference between 0.2V and 1.7V.
Turn off the power supply and reference. Do not turn
on the power supply until all connections are com-
pleted.
Remove the shunt from jumper JU1.
Connect the positive power-supply terminal to the
EV kit PCB pad labeled IN.
Connect the negative power-supply terminal to the
EV kit PCB pad labeled GND1.
Connect the positive voltage-reference terminal to
the EV kit PCB pad labeled REFIN.
Connect the negative voltage-reference terminal to
the EV kit PCB pad labeled AGND.
Connect the load from OUT to GND2.
4)
5)
6)
7)
8)
9)
Skip Mode
Table 1. Jumper Settings (JU1, JU2)
JUMPER
JU1
JU2
SHUNT POSITION
OPEN
Shutdown mode
—
1-2
Output enabled
Forced-PWM operation
2-3
—
Skip mode enabled for light loads with V
OUT
< 1V
2
Maxim Integrated
Microcontroller MCU
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