19-1154; Rev 0; 10/96
MAX846A Evaluation Kit
_______________General Description
The MAX846A evaluation kit (EV kit) is a stand-alone
charger for lithium-ion (Li-Ion) batteries. The charging
regulator consists of voltage and current loops driving
an external, low-cost, PNP pass transistor. In voltage-
regulation mode, a current-to-voltage converter supplies
a voltage proportional to the current flowing through the
Li-Ion battery. The float voltage and charging current
can be programmed with just two external resistors. The
MAX846A EV kit is shipped configured for charging two
Li-Ion cells at 800mA from a 10V power source.
The MAX846A EV kit is a fully assembled and tested
surface-mount printed circuit board.
____________________________Features
o
0.5% Internal Reference for Li-Ion Charging
o
Regulates Voltage and Current into Battery
o
Selectable 1 or 2-Cell Li-Ion Charge
o
1%, 3.3V, On-Chip, Low-Dropout Linear Regulator
o
1µA Max Battery Drain when Off
o
Power-Good Function
o
Surface-Mount Components
o
Fully Assembled and Tested
Evaluates: MAX846A
____________________Component List
DESIGNATION QTY
C1
C2
C3
C4, C5, C6
C7
D1
Q1
R1, R6
R2
R3
R4
R5
U1
J1
J2
JU1–JU4
JU5
None
None
None
1
1
1
3
1
1
1
2
1
1
1
1
1
1
1
4
1
0
4
1
DESCRIPTION
22µF, 35V electrolytic capacitor
Sanyo 35CV22GX
0.1µF ceramic capacitors
4.7µF, 16V tantalum capacitor
Sprague 595D475X0016A2B
0.01µF ceramic capacitors
4.7µF, 35V electrolytic capacitor
Sanyo 35CV4.7GX
1A, 100V fast-recovery diode
Nihon EC10DS1
PNP power transistor (SOT-223)
Zetex FZT749
0.400Ω, 1%, 1/2W resistors
Dale WSL-2010-R400-F or
IRC LR2010-01-R400-F
680Ω, 5% resistor
10kΩ, 5% resistor
100kΩ, 5% resistor
825kΩ, 1% resistor
Maxim MAX846AEEE
PC mount jack
RDI Electronics DJ-005
2-pin term connector
3-pin headers
2-pin header
6.0V at 800mA AC adapter (1 cell)
James Electronics 14311 (not supplied)
9V at 830mA AC adapter (2 cells)
James Electronics 14323 (not supplied)
Shunts
MAX846A PC board
________________________________________________________________
Maxim Integrated Products
1
______________Ordering Information
PART
MAX846EVKIT
TEMP. RANGE
0°C to +70°C
BOARD TYPE
Surface Mount
______________Component Suppliers
SUPPLIER
AVX
Dale-Vishay
IRC
James Electronics
Motorola
Nichicon
Nihon
Sanyo
Sprague
RDI Electronics
Vishay/Vitramon
Zetex
PHONE
(803) 946-0690
(800) 282-4975
(402) 564-3131
(512) 992-7900
(312) 463-6500
(602) 303-5454
(847) 843-7500
(805) 867-2555
(619) 661-6835
(603) 224-1961
(914) 773-1000
(203) 268-6261
(516) 543-7100
FAX
(803) 626-3123
(402) 563-6418
(512) 992-3377
(312) 463-1504
(602) 994-6430
(847) 843-2798
(805) 867-2698
(619) 661-1055
(603) 224-1430
(914) 773-1111
(203) 452-5670
(516) 864-7630
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
MAX846A Evaluation Kit
Evaluates: MAX846A
_________________________Quick Start
The MAX846A Evaluation Kit (EV kit) is fully assembled
and tested. Follow these steps to verify board opera-
tion.
Do not turn on the power supply until all con-
nections are completed.
1) Place the shunt across JU2’s pins to set the number
of cells being charged in the battery pack. The EV
kit is shipped configured for two lithium-ion (Li-Ion)
cells (shunt across pins 1 and 2).
2) Set the charging current with R1 and R6. The charge
current is preset for 800mA (R1 = R6 = 400mΩ).
For 400mA charge current, remove R6. Consult the
battery manufacturer for recommended charging
currents.
3) Connect the battery pack to the two-pin power con-
nector J2. Observe the polarity markings.
4) Connect the external supply voltage to the VIN and
GND pads. For charging one cell, use a 6V supply;
for 2 cells, use a 10V supply.
5) Turn on the power supply to the board and confirm
the voltage across the battery using a voltmeter.
Jumper Selection
The three-pin header JU1 selects shutdown mode.
Table 2 lists the selectable jumper options.
Table 2. Jumper JU1 Functions
SHUNT
LOCATION
1&2
2&3
ON PIN
Connected to
PWROK
Connected to GND
MAX846A
OUTPUT
Enabled
Shutdown mode,
I
BATT
< 1µA
The three-pin header JU3 disables the voltage-regulation
loop. Table 3 lists the selectable jumper options. The
MAX846A EV kit is shipped configured for two Li-Ion
cells with the voltage-regulation loop enabled.
Table 3. Jumper JU3 Functions
SHUNT
LOCATION
1&2
2&3
OFFV PIN
Connected to VL
Connected to GND
CHARGER
STATUS
Voltage loop
disabled
Voltage loop
enabled
_______________Detailed Description
The MAX846A EV kit is a stand-alone charger for Li-Ion
batteries. The charging regulator consists of voltage
and current loops driving an external, low-cost, PNP
pass transistor (Q1). The MAX846A requires an input
1V greater than the maximum charging voltage.
Higher input voltages and charging currents can be
used as long as Q1’s power dissipation does not
exceed 2W.
(At 2W, Q1 may exceed +70°C). For high-
er power dissipation and cooler operation, replace Q1
with a TO220 transistor (TIP42) and heatsink in holes
provided.
The three-pin header JU4 selects the float-voltage refer-
ence. An 825kΩ, 1% resistor is provided for adjusting the
float voltage. Table 4 lists the selectable jumper options.
The MAX846A EV kit is shipped configured for two Li-Ion
cells with the default float voltage reference at 8.4V.
Table 4. Jumper JU4 Functions
SHUNT
LOCATION
1&2
2&3
Open
VSET PIN
Connected to VL
Connected to GND
Floating
FLOAT
VOLTAGE
Adjust up
Adjust down
8.4V for 2 Li-Ion cells,
4.2V for 1 Li-Ion cell
Selecting the Number of Li-Ion Cells
Jumper JU2 selects the number of battery-pack cells.
Place the shunt across JU2’s pins to select the desired
number of cells (Table 1). The MAX846A EV kit is
shipped configured for two cells.
Table 1. Jumper JU2 Functions
SHUNT
LOCATION
1&2
2&3
CELL2 PIN
Connected to VL
Connected to GND
NUMBER OF
CELLS
2
1
The two-pin header JU5 enables adjustment of the
current-regulation point. When shorted, a 10kΩ, 5%
resistor (R3) connects the ISET pin to GND, and the
charging current is determined by R1 and R6. During
float charge, the charging current can be monitored
at the ISET pin. When open, an external voltage source
must be connected between ICNTRL and GND to adjust
the charging current. Refer to the
Detailed Description
in the MAX846A data sheet for more information.
2
_______________________________________________________________________________________
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