MAX8814EVKIT [MAXIM]
Fully Assembled and Tested;
| 型号： | MAX8814EVKIT |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Fully Assembled and Tested |
| 文件： | 总7页 (文件大小：110K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-3100; Rev 0; 12/07
MAX8814 Evaluation Kit
Evluates:MAX814
General Description
Features
♦ CCCV, Thermally Regulated Linear 1-Cell Li+
The MAX8814 evaluation kit (EV kit) is a fully assembled
and tested printed-circuit board (PCB) for evaluating
the MAX8814 28V linear Li+ battery charger. The
MAX8814 EV kit operates from an input supply range of
4.25V to 28V, but the IC disables charging if the input
voltage exceeds 7V to protect against unqualified or
faulty AC adapters. The MAX8814 EV kit features an
adjustable fast-charge current set by an external resis-
tor (R2). Other features include an active-low control
input (EN) and an active-low input power source detec-
tion output (POK). The IC also features a booting assis-
tant circuit that distinguishes input sources and battery
connection and provides an output signal (ABO) for
system booting.
Battery Charger
♦ No External MOSFET, Reverse Blocking Diode, or
Current-Sense Resistor
♦ Programmable Fast-Charge Current (1A
max)
RMS
♦ Proprietary Die Temperature Regulation Control
(+115°C)
♦ 4.25V to 28V Input Voltage Range with Input OVP
Above 7V
♦ Charge-Current Monitor for Fuel Gauging (ISET)
♦ Low Dropout Voltage (300mV at 500mA)
♦ Input Power-Source Detection Output (POK) and
Charge-Enable Input (EN)
Ordering Information
♦ Soft-Start Limits Inrush Current
♦ Output for Autobooting (ABO)
♦ Fully Assembled and Tested
PART
TYPE
MAX8814EVKIT+
EV Kit
+Denotes lead-free and RoHS-compliant.
Component List
DESIGNATION QTY
DESCRIPTION
DESIGNATION QTY
DESCRIPTION
2-pin header, 0.1in center
Sullins PEC36SAAN
1µF 10ꢀ, 35V X5R ceramic
capacitor (0603)
JU1
1
C1
1
Digi-Key S1012E-36-ND
Taiyo Yuden GMK107BJ105K
Not installed, 10kΩ 5ꢀ
resistors—PCB short (0402), lead free
Not installed, 0.1µF 10ꢀ, 10V X5R
ceramic capacitors (0402)
TDK C1005X5R1A104K
Taiyo Yuden LMK105BJ104K
Murata GRM155R61A104K
R1, R4
0
C2, C4
0
R2
R3
1
1
2.8kΩ 1ꢀ resistor (0402), lead free
1MΩ 5ꢀ resistor (0402), lead free
28V linear lit battery charger (8-pin,
TDFN, 2mm x 2mm)
Maxim MAX8814ETA+
(Top Mark: ABI)
2.2µF 10ꢀ, 10V X5R ceramic
capacitor (0603)
Taiyo Yuden LMK107BJ225K
Murata GRM188R61A225K
U1
—
1
1
C3
1
PCB: MAX8814 Evaluation Kit+
Component Suppliers
SUPPLIER
PHONE
WEBSITE
Digi-Key Corp.
800-344-4539
770-436-1300
760-744-0125
408-573-4150
847-803-6100
402-563-6866
www.digikey.com
Murata Electronics North America, Inc.
Sullins Electronics Corp.
Taiyo Yuden
www.murata-northamerica.com
www.sullinselectronics.com/tek9.asp
www.t-yuden.com
TDK Corp.
www.component.tdk.com
www.vishay.com
Vishay
Note: Indicate that you are using the MAX8814 when contacting these component suppliers.
________________________________________________________________ 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.
MAX8814 Evaluation Kit
8) Connect a digital multimeter (DMM2) from POK to
Quick Start
Recommended Equipment
Before beginning, the following equipment is needed:
GND.
9) Connect a digital multimeter (DMM3) from ABO to
GND.
•
•
•
•
•
28V power supply (PS1) capable of 1A
5V power supply (PS2) capable of 100mA
Four digital multimeters (DMM1–DMM4)
One 10A ammeter
10) Connect a digital multimeter (DMM4) from ISET to
GND.
11) Turn on PS1 and then turn on PS2.
12) Remove the shunt on JU1 to put the EV kit in enable
mode.
A single-cell lithium-ion (Li+) battery (not fully
charged)
13) If the charger is in fast-charge mode, verify that the
ammeter reads approximately 570mA. If the charg-
er is in precharge mode, verify that the ammeter
reads 57mA.
Procedure
The MAX8814 EV kit is a fully assembled and tested
surface-mount PCB. Follow the steps below and see
Figure 1 to set up and verify board operation. Caution:
Do not turn on power supplies until all connections
are made.
14) If the charger is in fast-charge mode, verify that the
voltage read at DMM4 is 1.4V. If the charger is in
precharge mode, verify that the voltage read at
DMM4 is 0.14V.
1) Preset the power supply (PS1) to 5V. Turn off the
power supply. Do not turn on the power supply
until all connections are made.
15) Verify that the voltage read by DMM2 is 0V, indicat-
Evluates:MAX814
ing POK is low.
16) Verify that the voltage read by DMM3 is approxi-
mately the same voltage read by DMM1.
2) Preset the power supply (PS2) to 5V. Turn off the
power supply. Do not turn on the power supply
until all connections are made.
17) When the battery is fully charged, DMM1 reads 4.2V.
18) Turn off the input power supply (PS1).
3) Verify that a shunt is installed on JU1 (EN) to set the
EV kit in disable mode.
19) Verify that the voltage read by DMM2 is near 5V
and the voltage read by DMM3 is 0V.
4) Connect the positive lead of the power supply
(PS1) to the EV kit pad labeled IN. Connect the
negative lead of the power supply to the EV kit pad
labeled GND.
20) Connect ABI to the positive terminal of PS2.
21) Verify that the voltage read at DMM3 is approxi-
mately the same voltage read by DMM1.
When evaluation of the MAX8814 EV kit is completed,
use the following steps to power down the EV kit:
5) Connect the positive lead of the power supply
(PS2) to the EV kit pad labeled VI/O. Connect the
negative lead of the power supply to the EV kit pad
labeled GND. Do not connect the PS2 positive lead
to ABI until instructed.
1) Install a shunt on JU1.
2) Turn off all power supplies.
3) Remove the battery.
6) Observe correct Li+ cell polarity. Connect a single-
cell Li+ cell and 10A ammeter, as shown in Figure
1. The positive lead of the ammeter must connect to
BATT+ and the negative lead to the positive termi-
nal of the Li+ battery.
4) Disconnect all test leads from the EV kit.
Table 1. Jumper Settings
7) Connect a digital multimeter (DMM1) across the
Li+ battery. Note the battery voltage. If the
JUMPER
FUNCTION
Shorts EN (active-low enable input) to VI/O
(system supply). Short JU1 to disable the IC. EN
has an internal pulldown resistor to GND. Leave
JU1 open to enable the IC.
V
< 2.5V, the charger starts in precharge
BATT
mode. If V
≥ 2.5V, the charger starts up in fast-
BATT
JU1
charge mode.
2
_______________________________________________________________________________________
MAX8814 Evaluation Kit
Evluates:MAX814
BATT-
-
GND
IN
-
POWER SUPPLY (PS1)
DMM1
4.25V TO 28V
Li+
+
BATT+
+
+
-
MAX8814
EVALUATION KIT+
10A AMMETER
POK
VI/O
+
DMM2
+
-
ISET
-
DMM4
+
JU1
POWER SUPPLY (PS2)
1.3V TO 5V
-
+
DMM3
-
SHUNT INSTALLED = IC DISABLED
SHUNT NOT INSTALLED = IC ENABLED
READ PROCEDURE FOR DETAILS
Figure 1. Test Procedure Setup for MAX8814 EV Kit
Charger Enable Input
Detailed Description
The MAX8814 contains an active-low logic input (EN)
used to enable the charger. Drive EN low, leave uncon-
nected, or connect to GND to enable the charge-control
circuitry. Drive EN high to disable the charge-control
circuitry. EN has an internal 200kΩ pulldown resistor.
The MAX8814 charger uses voltage, current, and ther-
mal-control loops to charge a single Li+ cell and pro-
tect the battery (Figure 1). When an Li+ battery with a
cell voltage below 2.5V is inserted, the MAX8814
charger enters the prequalification stage where it
precharges that cell with 10ꢀ of the user-programmed
fast-charge current. When battery voltage reaches
2.5V, the charger soft-starts as it enters the fast-charge
stage. In the MAX8814, the fast-charge current level is
programmed through a resistor from ISET to GND. As
the battery voltage approaches 4.2V, the charging cur-
rent is reduced. Once the battery voltage reaches 4.2V,
the IC then enters a constant voltage regulation mode
to maintain the battery at full charge.
POK Output
The open-drain POK output asserts low when V
≥
IN
4.25V and (V - V
) ≥ 40mV (typ V rising). POK
IN
IN
BATT
requires an external pullup resistor (1MΩ typ) to an
external power supply (R3 in Figure 2). POK is high
impedance when V
≥ (V - 40mV).
BATT
IN
Autobooting Assistant
The MAX8814 contains an autobooting assistant circuit
that generates an enable signal for system booting
(ABO). The booting assistant functions as an internal
“OR” gate (refer to Figure 1 in the MAX8814 IC data
sheet for details). The first input is dependent on the
state of the internal POK signal and the second input is
an external signal applied to ABI.
Thermal Regulation
The thermal-regulation loop limits the MAX8814 die
temperature to +115°C by reducing the charge current
as necessary. This feature not only protects the IC from
overheating, but also allows a higher charge current
without risking damage to the IC.
_______________________________________________________________________________________
3
MAX8814 Evaluation Kit
The second input signal (ABI) is driven by an external
source (Table 2). ABI enables an autoboot signal (ABO
high) when a battery is connected at BATT and is inde-
pendent of POK. If POK is low, the booting assistant
always drives ABO high regardless of ABI. ABI is
pulled to GND through an internal 200kΩ resistor. If ABI
is driven externally, an RC filter (R1 and C2 in Figure 2)
is required for ESD protection and noise filtering. To
install R1, cut the copper trace across the R1 pads. If
ABI is supplied by a system’s internal GPIO, or logic,
the RC filter is not required.
Charge-Current Selection
The maximum charging current is programmed by an
external resistor connected from ISET to GND (R
,
ISET
R2 in Figure 2). Calculate R
as follows:
ISET
1596V
R
=
ISET
I
FAST−CHARGE
where I
is in amperes and R
is in
ISET
FAST-CHARGE
ohms. ISET can be used to monitor the charge-current
level. The output current from ISET is 877.2µA per
ampere of charging current. The output voltage at ISET
is proportional to the charging current:
Table 2. ABO and POK States
ABI
Low
High
BATT
Present
Present
POK
CHARGER STATE
Shutdown
ABO
Low
I
× R
ISET
1140
CHARGE
High-Z
High-Z
V
=
ISET
Shutdown
High
Fast-charge/voltage
regulation
The voltage at ISET is nominally 1.4V at the selected
fast-charge current, and falls with charging current as
the cell becomes fully charged or as the thermal-
regulation circuitry activates.
X
X
Not present
Present
Low
Low
High
High
Evluates:MAX814
Fast-charge/voltage
regulation
X = Don’t care.
DC Input Sources
The MAX8814 operates from a well-regulated DC source.
The full charging input voltage range is 4.25V to 7V. The
device can withstand up to 28V on the input without dam-
age to the IC. If V is greater than 7V, the internal overvolt-
IN
age-protection circuitry disables charging until the input
falls below 7V. An appropriate power supply must provide
at least 4.25V at the desired peak charging current.
1
8
IN
IN
BATT
BATT+
BATT-
C1
1μF
C3
2.2μF
GND
U1
R1
PCB SHORT
4
5
ABI
ABI
EN
MAX8814
C2
JU1
OPEN
6
7
EN
VI/O
R3
1MΩ
ABO
ABO
POK
POK
ISET
GND
EP
ISET
R4
PCB SHORT
2
3
C4
R2
2.8kΩ
OPEN
1%
Figure 2. MAX8814 EV Kit Schematic
_______________________________________________________________________________________
4
MAX8814 Evaluation Kit
Evluates:MAX814
Figure 3. MAX8814 EV Kit Component Placement Guide—Component Side
_______________________________________________________________________________________
5
MAX8814 Evaluation Kit
Evluates:MAX814
Figure 4. MAX8814 EV Kit PCB Layout—Component Side
6
_______________________________________________________________________________________
MAX8814 Evaluation Kit
Evluates:MAX814
Figure 5. MAX8814 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 _____________________ 7
© 2007 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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