General Description

The MAX1926 evaluation kit (EV kit) is a complete, fully
assembled and tested, single-cell lithium-ion (Li+) bat-
tery charger. The EV kit provides a 4.2V output from
input as high as 12V, and delivers up to 1A charge cur-
rent. 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

o 5V to 12V Input Voltage Range
o Up to 1A Fast Charge Current
o LED Charge Status and Fault Indicator
o 12-Pin Thin QFN Package
o Surface-Mount Construction
o Fully Assembled and Tested

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 pos-

itive 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 cur-
rent 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.

Evaluates: MAX1925/MAX1926

MAX1926 Evaluation Kit

________________________________________________________________ Maxim Integrated Products

DESIGNATION QTY

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)

D1, D2

1A, 30V Schottky diodes
Nihon EP10QY03

Surface-mount LED (0805)

JU1

2-pin header

JU2

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

0.14

±1%, 1/2W sense resistor

(1206)
IRC LR1206-01-R140-F

100k

±5% resistor (0603)

R3, R4

Not installed, resistors (0603)

10k

±5% resistor (0603)

MAX1926ETC 12-pin thin QFN
4mm

4mm, top mark AABF

None

Shunt

None

MAX1926 PC board

Ordering Information

19-2594; Rev 1; 11/02

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.

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 sam-
ple with the MAX1926EVKIT.

Component List

Evaluates: MAX1925/MAX1926

Detailed Description

The MAX1926 EV kit is a fully assembled and tested sin-
gle-cell Li+ battery charger. The EV kit contains an exter-
nal P-channel MOSFET for current switching and can
deliver up to 1A of current to a Li+ battery. An LED indi-
cates 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 300k

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 ther-
mistor or a 10k

resistor. The MAX1926 is disabled when

the resistance connected to THRM is greater than 28.69

or less than 3.967k

. The MAX1926 EV kit comes with

THRM connected to a 10k

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.

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 cir-
cuits, 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 100k

resistors R3 and R4

to enable the IC.

MAX1926 Evaluation Kit

_______________________________________________________________________________________

SUPPLIER

PHONE

FAX

WEBSITE

AVX

843-946-0238

843-626-3123

www.avxcorp.com

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

Component Suppliers

Note: Please indicate that you are using the MAX1925/MAX1926 when contacting these component suppliers.

SHUNT

LOCATION

EN PIN

MAX1926 OUTPUT

Installed

Connected to GND

MAX1926 is disabled

Not installed

EN internally pulled
to 3V

MAX1926 is enabled

Table 1. JU1 Functions

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 10k

pulldown resistor

MAX1926 is enabled if EN
is high

Table 2. JU2 Functions

Evaluates: MAX1925/MAX1926

MAX1926 Evaluation Kit

_______________________________________________________________________________________

CHARGING STATE

CONDITION

LED STATE

Off

EN low, or no battery, or no wall power.

Off.

Prequal1

Charge current = 4mA until BATT reaches 2V.

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 full-
charge timeout.

Fault Batt Voltage

Battery voltage has exceeded 4.35V.

Blinking at 0.5Hz. Clear fault by cycling
input power, THRM, or EN.

MAX1925: Off.

Fault Temp

Temperature has risen above +50

°C or fallen below 0°C if a

thermistor is installed. Temp fault clears by itself.

MAX1926: Blinking at 0.5Hz.

None

Initial power-up or enable with no battery.

Blinking at rapid rate as charger cycles
through Reset, Prequal1, and Done.

Table 3. LED States

MAX1926

VIN

GND

C1
10

µF

16V

OPEN

R4
OPEN

100k

ACON

µH

0.14

BATT

GND

µF

6.3V

0.1

µF

JU1

THRM

JU2

SHORTED

BY PC TRACE

10k

OPEN

ACON

CHG

THRM

INP

EXT

BATT

PGND

GND

Figure 1. MAX1926 EV Kit Schematic

Evaluates: MAX1925/MAX1926

MAX1926 Evaluation Kit

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

Printed USA

is a registered trademark of Maxim Integrated Products.

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

Part Number MAX1926EVKIT