Low-Cost Multichemistry Battery Chargers
2) Place the IC and signal components. Keep the
main switching node (LX node) away from sensitive
analog components (current-sense traces and REF
capacitor). Important: The IC must be no further
than 10mm from the current-sense resistors.
current-sense lines and REF. Place ceramic
bypass capacitors close to the IC. The bulk capac-
itors can be placed further away.
3) Use a single-point star ground placed directly
below the part at the backside exposed pad of the
MAX1908/MAX8724. Connect the power ground
and normal ground to this node.
Keep the gate-drive traces (DHI, DLO, and BST)
shorter than 20mm, and route them away from the
Table 2. Component List for Circuit of Figure 2
DESIGNATION QTY
DESCRIPTION
Schottky diode
DESIGNATION QTY
DESCRIPTION
10µF, 50V 2220-size ceramic
capacitors
TDK C5750X7R1H106M
D3
1
Central Semiconductor CMPSH1-4
C1
C4
2
1
10µH, 4.4A inductor
Sumida CDRH104R-100NC
TOKO 919AS-100M
L1
1
22µF, 25V 2220-size ceramic
capacitor
TDK C5750X7R1E226M
Dual, N-channel, 8-pin SO MOSFET
Fairchild FDS6990A or FDS6990S
N1
P1
1
1
1µF, 25V X7R ceramic capacitor
(1206)
Murata GRM31MR71E105K
Taiyo Yuden TMK316BJ105KL
TDK C3216X7R1E105K
Single, P-channel, 8-pin SO MOSFET
Fairchild FDS6675
C5
1
2
4
R5
R6
1
1
1
1
1
1
1
2
1
1
2
1kΩ 5% resistor (0603)
59kΩ 1% resistor (0603)
19.6kΩ 1% resistor (0603)
12kΩ 5% resistor (0603)
15kΩ 5% resistor (0603)
33Ω 5% resistor (0603)
10.5kΩ 1% resistor (0603)
8.25kΩ 1% resistors (0603)
19.1kΩ 1% resistor (0603)
22kΩ 1% resistor (0603)
10kΩ 1% resistors (0603)
0.01µF, 16V ceramic capacitors (0402)
Murata GRP155R71E103K
Taiyo Yuden EMK105BJ103KV
TDK C1005X7R1E103K
R7
C9, C10
R11
R12
R13
0.1µF, 25V X7R ceramic capacitors
(0603)
Murata GRM188R71E104K
TDK C1608X7R1E104K
R14
C11, C14,
C15, C20
R15, R16
R17
1µF, 6.3V X5R ceramic capacitors
(0603)
Murata GRM188R60J105K
Taiyo Yuden JMK107BJ105KA
TDK C1608X5R1A105K
R18
R19, R20
C12, C13, C16
3
0.01Ω 1%, 0.5W 2010 sense resistor
Vishay Dale WSL2010 0.010 1.0%
IRC LRC-LR2010-01-R010-F
RS1
1
10A Schottky diode (D-PAK)
Diodes, Inc. MBRD1035CTL
ON Semiconductor MBRD1035CTL
D1 (optional)
D2
1
1
0.015Ω 1%, 0.5W 2010 sense
resistor
Vishay Dale WSL2010 0.015 1.0%
IRC LRC-LR2010-01-R015-F
RS2
U1
1
1
Schottky diode
Central Semiconductor
CMPSH1–4
MAX1908ETI or MAX8724ETI
Chip Information
TRANSISTOR COUNT: 3772
PROCESS: BiCMOS
26 ______________________________________________________________________________________
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
