19-1816; Rev 0; 10/00
MAX1757/MAX1758 Evaluation Kits
General Description
The MAX1757/MAX1758 evaluation kits (EV kits) are
assembled and tested PC boards that implement a
step-down, switching lithium-ion (Li+) battery charger.
The MAX1757 EV kit can be set to charge 1- to 3-series
cells, and the MAX1758 EV kit can be set to charge 1-
to 4-series cells. The cell voltage can be set between
4.0V and 4.4V using standard 1% resistors while main-
taining 1% overall regulation voltage accuracy. Three
LEDs indicate the charging status.
The MAX1757/MAX1758 EV kits detect faulty cells and
terminate charging. Two capacitors are used to set the
charge termination, prequalification, and fault timeout
periods. A user-supplied thermistor may be connected
to either EV kit to monitor battery temperature and sus-
pend charging for over-/undertemperature conditions.
Features
o
Complete Li+ Charging Solution up to 3-Series
Cells (MAX1757) and 4-Series Cells (MAX1758)
o
1.5A Battery-Charging Current
o
Low Heat/High Efficiency
o
300kHz PWM Operation
o
o
o
o
Up to 14V Input Voltage Range (MAX1757)
Up to 28V Input Voltage Range (MAX1758)
28-Pin SSOP Package
Surface-Mount Construction
Evaluate: MAX1757/MAX1758
o
Fully Assembled and Tested
Ordering Information
PART
MAX1757EVKIT
MAX1758EVKIT
IC PACKAGE
28 SSOP
28 SSOP
Component List
DESIGNATION QTY
C1, C2, C3,
C7, C14, C17,
C18
DESCRIPTION
0.1µF, 50V X7R ceramic
capacitors (0805)
Murata GRM40-034X7R104K050
or Taiyo Yuden UMK212BJ104KG
1µF, 10V X7R ceramic capacitor
Taiyo Yuden LMK212BJ105MG
or Murata GRM40X7R105K10
1000pF, 50V X7R ceramic
capacitors
0.1µF, 50V X7R ceramic
capacitors (1206)
22µF, 35V, 0.300Ω, low-ESR
tantalum capacitors
AVX TPSE226M035R0300 or
Kemet T495X226M035AS
0.22µF, 50V X7R ceramic capacitor
Taiyo Yuden UMK316BJ224ML
4.7µF, 10V X5R ceramic capacitor
Taiyo Yuden LMK316BJ475ML
or Murata GRM42-6X5R475K10
68µF, 20V, 0.150Ω, low-ESR
tantalum capacitor
AVX TPSE686M020R0150
DESIGNATION QTY
DESCRIPTION
Diodes, 1N4148-type
Fairchild MMSD4148,
Vishay Liteon/Diodes, Inc. 1N4148W,
or General Semiconductor 1N4148W
Schottky diodes, 3A, 30V
Nihon EC31QS03L or
Vishay Liteon/Diodes, Inc.
B330A
2-pin header
3-pin header
3-pin header (MAX1757 EV kit)
4-pin header (MAX1758 EV kit)
22µH, 2.5A inductor
Sumida CDRH104R-220NC
Light-emitting diodes (green), T1
Light-emitting diode (red), T1
0.05Ω
±1%,
0.5W sense resistor
Dale WSL-2010-R050F or
IRC LRC-LR2010-01-R050-F
10kΩ
±5%
resistors
Not installed
100kΩ
±1%
resistors
1kΩ
±5%
resistors
4.7Ω
±5%
resistors
MAX1757EAI (MAX1757 EV kit)
MAX1758EAI (MAX1758 EV kit)
7
D1, D3
2
C4
1
D2, D4
2
C5, C6, C19
C8, C9
3
2
JU1
JU2
JU3
L1
LED1, LED2
LED3
R1
R2, R12
R3–R6
R7, R8
R9, R10, R11
R13, R14
U1
1
1
1
1
2
1
1
2
0
2
3
2
1
C10, C11
2
C12
1
C13
1
C15
1
________________________________________________________________
Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX1757/MAX1758 Evaluation Kits
Evaluate: MAX1757/MAX1758
Quick Start
The MAX1757/MAX1758 EV kits are fully assembled
and tested surface-mount boards. Follow the steps
below to verify board operation.
Do not turn on the
power supply until all connections are completed.
Observe all precautions on the battery manufactur-
er’s data sheet. Use only lithium-ion (Li+) cells with
this charger:
1) Set jumper JU3 to indicate the number of cells in the
battery pack (Table 1).
2) Place a shunt on jumper JU1 to disable the tempera-
ture monitoring functions.
3) Place a shunt across pins 1–2 on JU2 to enable the
MAX1757 or MAX1758.
4) For the MAX1757, connect a +7VDC to +14VDC
power supply with sufficient power rating across the
VIN and GND pads.
For the MAX1758, connect a +7VDC to +28VDC
power supply with sufficient power rating across the
VIN and GND pads.
5) Connect a lithium-ion (Li+) battery pack between the
BATT+ and BATT- pads.
6) Turn on the power supply.
7) Verify that LEDs 1, 2, and 3 indicate the correct
charging status.
thermistor (see
Jumper Selection
section).
If the charger is unable to enter the fast-charge or full-
charge states, charging is terminated and the fault LED
(red) lights to indicate a faulty battery.
For more information on the operation of the MAX1757
or MAX1758, refer to the
Detailed Description
sections
of the MAX1757 and MAX1758 data sheets.
Charging Status
The three LEDs on the EV kit indicate the charging status:
o
LED1 (FULL) indicates that the battery pack is being
charged with a constant voltage.
o
LED2 (FAST) indicates that the battery pack is being
charged with a constant current.
o
LED3 (FAULT) indicates that charging terminated ab-
normally.
Charging Current
The voltage at the ISETOUT pin sets the charging cur-
rent to the battery. The MAX1757/MAX1758 EV kits are
shipped with ISETOUT connected to REF. This sets the
charging current to the full-scale value of 1.5A.
To change the charging current to a lower value, cut
the trace shorting the two pads of R3 and install resis-
tors for R3 and R4. Use the equations below to calcu-
late the resistor values:
I
CHG
= (R4 / (R3 + R4)) x 1.5A
R3 = ((1.5A / I
CHG
) - 1) x R4
Use 100kΩ for R4.
Detailed Description
When battery charging is initiated, the charger enters
the prequalification state. In this state, the batteries are
charged at 1/10 of the programmed current limit while
the charger measures the battery to determine if it can
be charged. If the battery voltage is above 2.5V per
cell, charging begins. At this time, the batteries are
charged at a constant current (fast-charge state) or a
constant voltage (full-charge state). The charger exits
the full-charge state and enters the top-off state once
the battery current drops to 10% of the fast-charge cur-
rent, or the fast-charge timer expires. The charger
remains in the top-off state for 45 minutes, after which
charging is terminated.
Once charging is terminated, if the battery voltage
drops 5% from the fully charged voltage, charging
automatically restarts.
If at any time during charging, the thermistor input
senses a temperature below 0°C or above +50°C,
charging suspends until the temperature returns to a
safe level. This kit is shipped with a 10kΩ resistor to
disable the temperature monitoring function. If temper-
ature monitoring is required, connect the appropriate
2
Input Current
The input current limit is set by sense resistor R1 and
by the voltage applied to the ISETIN pin. This sets the
input current limit to 2A (100mV/50mΩ). The
MAX1757/MAX1758 EV kits are shipped with ISETIN
connected to REF and a 50mΩ sense resistor.
To change the input current limit to a lower value, cut
the trace shorting the two pads of R5 and install resis-
tors for R5 and R6. Use the equations below to calcu-
late the resistor values:
I
IN
= (R6 / (R5 + R6)) x 2A
R5 = ((2A / I
IN
) - 1) x R6
Use 100kΩ for R6.
To further increase the input current limit, reduce the
value of sense resistor R1.
_______________________________________________________________________________________
MAX1757/MAX1758 Evaluation Kits
Table 1. Jumper Selection
SUPPLIER
JUMPER
JUMPER
POSITION
FUNCTION
Open before
connecting a
thermistor from
THERM to GND
pads.
Bypasses THERM
with a 10kΩ
resistor.
SHDN
= high.
MAX1757/MAX1758
enabled.
SHDN
= low.
MAX1757/MAX1758
disabled.
Drive
SHDN
pad
with an external
signal.
CELL = GND. Cell
count = 1.
CELL = VL. Cell
count = 4.
(MAX1758 only)
CELL = REF. Cell
count = 3.
CELL = Float. Cell
count = 2.
AVX
BC Components
Dale-Vishay
Fairchild
General
Semiconductor
International
Resistive Co. (IRC)
Kemet
Murata
Nihon
Sumida
Taiyo Yuden
Vishay
Liteon/Diodes, Inc.
Component Suppliers
PHONE
803-946-0690
803-772-2500
402-564-3131
408-822-2000
631-847-3000
310-322-3331
408-986-0424
814-237-1431
661-867-2555
847-956-0666
408-573-4150
805-446-4800
402-563-6418
408-822-2102
631-847-3236
310-322-3332
408-986-1442
814-238-0490
661-867-2698
847-956-0702
408-573-4159
805-446-4850
FAX
803-626-3123
Evaluate: MAX1757/MAX1758
Open
JU1
Closed*
1–2*
JU2
2–3
Open
Note:
Please indicate that you are using the MAX1757 or
MAX1758 when contacting these manufacturers.
1–2*
1–3
JU3
1–4
Open
*Default
position
Jumper Selection
Jumper JU1 connects the thermistor input (THERM) to
GND through a 10kΩ resistor, disabling temperature
qualification. To enable temperature qualification
(charging between 0°C and +50°C), remove the shunt
from JU1 and connect a thermistor (BC Components
part # 2322-640-63103 or equivalent) to the THERM
and GND pads. For more information, refer to the
MAX1757 and MAX1758 data sheets.
The EV kits can be placed in shutdown mode using
jumper JU2. (See Table 1 for jumper settings.)
Jumper JU3 selects the number of series cells to be
charged. (See Table 1 for jumper settings.)
______________________________________________________________________________________
3
Evaluate: MAX1757/MAX1758
4
THM
DCIN
JU1
D2
24
C1
0.1µF
CSSP
C8
0.1µF R14
4.7Ω
C9
0.1µF
9
HSD
10
19
20
C14
0.1µF
BST
D3
VL
VL
2
ISETIN
18
R6
OPEN
PGND
7
VADJ
21
CS
C17
0.1µF
11
CELL
BATT
8
C18
0.1µF
VL
FULLCHG
12
TIMER1
FASTCHG
13
C6
1000pF
15
C5
1000pF
16
R9
1k
LED1
+
+
+
MAX1757/MAX1758 Evaluation Kits
Figure 1. MAX1757/MAX1758 EV Kit Schematic
28
VIN
R13
4.7Ω
R1
0.05Ω
1%
C7
0.1µF
CCI
27
D1
23
C2
0.1µF
R2
10k
25
C19
1000pF
HSD
LX
5
C4
1µF
3
ISETOUT
R4
OPEN
1
C13
4.7µF
GND
22
D4
REF
R3
(SHORTED
BY PCB TRACE)
LX
L1
22µH
CCV
C10
22µF
35V
C11
22µF
35V
C12
0.22µF
C3
0.1µF
CCS
CSSN
4
U1
MAX1757
MAX1758
26
SYSTEM
LOAD
R5
(SHORTED
BY PCB TRACE)
R7
100k
1%
VL
THERM
R12
10k
*
3
1
2
JU2
SHDN
17
2
3
1 JU3
4
R8
100k
1%
BATT+
C15
68µF
BATT-
SHDN
_______________________________________________________________________________________
R10
1k
LED2
TIMER2
FAULT
GND
6
14
R11
1k
LED3
*MAX1758 ONLY
MAX1757/MAX1758 Evaluation Kits
Evaluate: MAX1757/MAX1758
1.0"
1.0"
Figure 2. MAX1757/MAX1758 EV Kit Component Placement
Guide—Component Side
Figure 3. MAX1757/MAX1758 EV Kit PC Board Layout—
Component Side
1.0"
Figure 4. MAX1757/MAX1758 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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 5
© 2000 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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