MAXIM MAX1926EVKIT

19-2594; Rev 1; 11/02
MAX1926 Evaluation Kit
The MAX1926 evaluation kit (EV kit) is a complete, fully
assembled and tested, single-cell lithium-ion (Li+) battery charger. The EV kit provides a 4.2V output from
input as high as 12V, and delivers up to 1A charge current. A light-emitting diode (LED) indicates the cell’s
charging status.
The EV kit can be also used to evaluate the MAX1925,
which is a single-cell Li+ battery charger with a 4.5V to
6.1V input voltage charge range.
Features
♦ 5V to 12V Input Voltage Range
♦ Up to 1A Fast Charge Current
♦ LED Charge Status and Fault Indicator
♦ 12-Pin Thin QFN Package
♦ Surface-Mount Construction
♦ Fully Assembled and Tested
Component List
DESIGNATION QTY
C1
C2
1
1
C3
1
C4
0
DESCRIPTION
10µF ±20%, 16V X5R
ceramic capacitor (1210)
Taiyo Yuden EMK325BJ106MN or
TDK C3225X5R1C106MT
22µF ±20%, 6.3V tantalum capacitor
(A case)
AVX TAJA226M006R
0.1µF ±10%, 16V X7R
ceramic capacitor (0603)
Taiyo Yuden EMK107BJ104KA or
TDK C1608X7R1C104KT or
Murata GRM39X7R104K016AD
Not installed, capacitor (0603)
1A, 30V Schottky diodes
Nihon EP10QY03
Surface-mount LED (0805)
2-pin header
D1, D2
2
D3
JU1
1
1
JU2
0
L1
1
Q1
1
R1
1
R2
1
Not installed, shorted by PC trace
10µH, 1.3A inductor
Toko A915AY-100M or
Sumida CDRH5D28-100
P-channel MOSFET 3-pin SOT23
Fairchild FDN360P
0.14Ω ±1%, 1/2W sense resistor
(1206)
IRC LR1206-01-R140-F
100kΩ ±5% resistor (0603)
R3, R4
0
Not installed, resistors (0603)
R5
1
U1
1
None
1
10kΩ ±5% resistor (0603)
MAX1926ETC 12-pin thin QFN
4mm x 4mm, top mark AABF
Shunt
None
1
MAX1926 PC board
Ordering Information
PART
TEMP RANGE IC PACKAGE
MAX1926EVKIT 0°C to +70°C 12 Thin QFN 4mm x 4mm
Note: To evaluate the MAX1925, request a MAX1925 free sample with the MAX1926EVKIT.
Quick Start
The MAX1926 EV kit is a fully assembled and tested
surface-mount board. Follow the steps below to verify
board operation. Do not turn on the power supply
until all connections are completed:
1) Verify that there is a no shunt across jumper JU1 (EN).
2) Connect a voltmeter across the EV kit’s BATT and
GND pads.
3) Connect a 5V to 12V power supply to the VIN pad.
Connect the power-supply ground to the GND pad
closest to VIN.
4) Observe correct Li+ cell polarity. Connect the positive terminal of a single-cell Li+ battery to the BATT
pad. Connect the negative terminal of the battery to
the GND pad closest to BATT.
5) Turn on the power supply. The LED turns on if the
battery voltage is below 4.2V and the charging current is above 125mA. See Table 3 for additional LED
state descriptions.
6) The LED turns off once the Li+ cell has been fully
charged.
To evaluate the MAX1925, see the Evaluating the
MAX1925 section.
________________________________________________________________ Maxim Integrated Products
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.
1
Evaluates: MAX1925/MAX1926
General Description
Evaluates: MAX1925/MAX1926
MAX1926 Evaluation Kit
Component Suppliers
PHONE
FAX
AVX
SUPPLIER
843-946-0238
843-626-3123
www.avxcorp.com
WEBSITE
Fairchild
888-522-5372
408-882-2102
www.fairchildsemi.com
IRC
361-992-7900
361-992-3377
www.irctt.com
Murata
770-436-1300
770-436-3030
www.murata.com
Nihon
81-33343-3411
81-33342-5407
www.niec.co.jp
Sumida
847-545-6700
847-545-6720
www.sumida.com
Taiyo Yuden
800-348-2496
847-925-0899
www.t-yuden.com
TDK
847-803-6100
847-390-4405
www.component.tdk.com
Toko
847-297-0070
847-699-1194
www.tokoam.com
Note: Please indicate that you are using the MAX1925/MAX1926 when contacting these component suppliers.
Detailed Description
The MAX1926 EV kit is a fully assembled and tested single-cell Li+ battery charger. The EV kit contains an external P-channel MOSFET for current switching and can
deliver up to 1A of current to a Li+ battery. An LED indicates the charging status of the battery. The maximum
charging time is set to 3 hours with 0.1µF at C3.
Jumper Selection
In the MAX1926, EN is internally pulled to 3V with an
internal 300kΩ resistance. When jumper JU1 is open,
EN goes to 3V and the charger is enabled. When JU1
is shorted, EN is 0V and the charger is disabled. See
Table 1 for JU1 functions
In the MAX1925, EN does not have an internal pullup
and must be driven high (5.5V max) or low. Extra pads
(R3 and R4) are provided so that EN can be driven
from a voltage-divider connected to a higher voltage
without exceeding the 5.5V limit.
Jumper JU2 provides options to connect THRM to a thermistor or a 10kΩ resistor. The MAX1926 is disabled when
Table 1. JU1 Functions
SHUNT
LOCATION
LED States
The LED on the EV kit is driven by the CHG pin.
Depending on the Li+ cell’s charging status, the pin is
low or high impedance, thus turning the LED on or off.
The LED blinks at 0.5Hz when the MAX1926 enters
Fault Prequal1, Fault Prequal 2, Fault Full, Fault BATT
Voltage, or the Fault Temp state. For driving logic circuits, remove the LED and install a pullup resistor from
a logic supply to CHG. Table 3 lists the LED states.
Evaluating the MAX1925
To evaluate the MAX1925, replace the MAX1926ETC
with a MAX1925ETC. Install 100kΩ resistors R3 and R4
to enable the IC.
Table 2. JU2 Functions
EN PIN
MAX1926 OUTPUT
Installed
Connected to GND
MAX1926 is disabled
Not installed
EN internally pulled
to 3V
2
the resistance connected to THRM is greater than 28.69Ω
or less than 3.967kΩ. The MAX1926 EV kit comes with
THRM connected to a 10kΩ resistor. JU2 is not populated
and is shorted by a PC trace. To connect a thermistor to
the EV kit, cut open the PC trace shorting JU2. Table 2
lists JU2 functions.
MAX1926 is enabled
JUMPER
STATE
THRM PIN
MAX1926 OUTPUT
Open
Connected to a
thermistor using
THRM pad
MAX1926 enabled with
valid THRM resistance
and EN high
Shorted
(by Default)
Connect to a 10kΩ
pulldown resistor
MAX1926 is enabled if EN
is high
_______________________________________________________________________________________
MAX1926 Evaluation Kit
Evaluates: MAX1925/MAX1926
Table 3. LED States
CHARGING STATE
CONDITION
LED STATE
Off
EN low, or no battery, or no wall power.
Prequal1
Charge current = 4mA until BATT reaches 2V.
Off.
On.
Prequal2
Charge current = C/10 (100mA) until BATT reaches 3V.
On.
Fast Charge
Charge current = C = 142mV/R1 (1A).
On.
Full Charge
Charge current has fallen to C/8 (125mA).
Off.
Fault Prequal1
BATT does not reach 2V before Prequal1 timeout.
Fault Prequal2
BATT does not reach 3V before Prequal2 timeout.
Fault Full
Charge current does not drop to C/8 (125mA) before fullcharge timeout.
Fault Batt Voltage
Battery voltage has exceeded 4.35V.
Fault Temp
Temperature has risen above +50°C or fallen below 0°C if a
thermistor is installed. Temp fault clears by itself.
None
Initial power-up or enable with no battery.
VIN
GND
S Q1
R2
100kΩ
D3
ACON
R3
OPEN
12 11
IN INP
4
MAX1925: Off.
MAX1926: Blinking at 0.5Hz.
Blinking at rapid rate as charger cycles
through Reset, Prequal1, and Done.
D1
C1
10µF
16V
Blinking at 0.5Hz. Clear fault by cycling
input power, THRM, or EN.
L1
10µH
D
D2
G
10
EXT
CS
ACON
6
U1
1
R4
OPEN
5
C3
0.1µF
EN
2
THRM
JU1
JU2
SHORTED
BY PC TRACE
3
CHG
CT
EN
THRM
R1
0.14Ω
1%
MAX1926
BATT
PGND
GND
7
9
C2
22µF
6.3V
BATT
GND
8
C4
OPEN
R5
10kΩ
Figure 1. MAX1926 EV Kit Schematic
_______________________________________________________________________________________
3
Evaluates: MAX1925/MAX1926
MAX1926 Evaluation Kit
Figure 2. MAX1926 EV Kit Component Placement Guide—Top
Silkscreen
Figure 3. MAX1926 EV Kit PC Board Layout—Component Side
Figure 4. MAX1926 EV Kit PC Board 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
© 2002 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.