High efficiency step-down controller demonstration board with
embedded 2 A LDO regulator based on the ST72F324L
Features
■ 1 % measurement accuracy
■ Firmware easily upgradeable
■ Li-ion battery or 2-cell NiMH batteries
■ 5 V supply
■ RoHS compliant
Description
The STEVAL-ISB002V1 is a universal battery
charger (UBC) demonstration board based on the
ST72F324L microcontroller.
The charger used in this demonstration board
uses a modified form of a non-inverting buckboost converter to support the charging voltage
requirement for single-cell Li-ion batteries.
STEVAL-ISB002V1
Data brief
STEVAL-ISB002V1
The board includes a 3.3 V power supply
generated from a KF33 regulator and a precision
reference voltage generated from the TL1431,
bearing in mind the accuracy requirement for
charging. A status LED is used to show the
charging status.
This demonstration board is capable of charging
single cell Li-ion batteries with in-built NTC or a 2cell NiMH battery from a 5 V supply. The firmware
is easily upgradeable and can be modified for
other ST7 microcontrollers depending on
application requirements.
November 2010 Doc ID 18257 Rev 1 1/4
For further information contact your local STMicroelectronics sales office.
www.st.com
4
Circuit schematic STEVAL-ISB002V1
1 Circuit schematic
Figure 1. Circuit schematic
10k
C4
2
OSC
ICC
AIN0
AIN1
R25
K
CCCL
RESET
ICCSEL
ICCDATA
I
0
1
123 4
5 6
7 8
9
CON1
HEADER5X2
VDD
GND
3
2
1
J1
XT
E
_
OSC
D
VD
F
n
10
C5
R21
4.7k
33pF
L
2
GND
ICCSE
OSC
OSC1
RESET
4
2
21
20
23
22
VSS
OSC2
OSC1
RESET
DDV
25
26
PE0
27
PE1
28
PB0
29
PB3
(HS)/
30
PB4
31
PDO
32
PD1
2
VAREF1VSS
AIN8/PF03PF1
U
2
5
4
AIN8
GNDVAREF
)
%
k(1
10
R14
D
VD
tLtd
v
icsP
n
icroelectro
IA
M
reater Noida-201308,UP
T
ND
S
I
UNIVERSAL_BA TT_CHARGER
G
OSC1
S1
4
LED
L
ICCSE
F4
P
10/
N
AI
6
-1
M
PW
Plo t no . 1, Kno wl ed ge ParkI II,
F
100n
2.2 uF/16V
100nF
C6
C7
C8
C9
IN0
AIN1
VDD
A
LED2
LED3
18
17
PA719PA6
PA4
PA
3
PC
7
PC
6
PC
5
PC
4
PC
3
PC
2
ST72F324LK2T6
PC
1
7
PF
PF6
PC0
7
8
LED1
16
15
14
ICCCLK
13
AIN14
12
ICCDATA
11
10
9
-2
M
PW
Y
C2
3
7
2
R133
Ni-MH BATTERY
1
2
3
J
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V-
Vin
5
6
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un
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e
To B
ot
100nF (N
)
%
1
.
0
(
15k
R17
k
R15
10
D2
6
5
T
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D
BI
I
R
GN
GN
DT
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B
D
D
GN
GN
KF33
3NC4
0
A
m
1000
uH/
L1
75
5
6
4
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B
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C
18
8
C1C2B
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LM258AD
)
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1
4
5%
0.
k(
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)
)
%
.5%
5
.
(0
k
3.3
AIN8
Li-IONBATTERY
th
)
R19
5k (0. 5%
16V
/
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R4
1
582
N
1
(0
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13
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R71k
5%)
.
0
(
R20
5k
0
N
I
A
Q4
23
100
31
2
1
Q
31
R26
470
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2STR2215
2STF1360
1
5
21
1
R
Q2
2ST
2
0
R5
47
R1215
T
2S
R22
BT1
V+
1N5821
y
Vsuppl
D1
100
Li-IONBATTER
123
J2
8
-
IN
V
V+
A
REF
A
V
D4
12
TL1431A I Z
.1%)
0
(
k
6
1
R
4.7
R3
100(1%)
Vin
D3
Vsupply
F1F
8
n
Vi
ut
IN4148
Vo
U1
1
VDD
2
E
S
U
LED
D5
470
R9
LED1
7
2
470
R
Y
R
BT2
E
ATT
Ni-MH B
3
1
R
68
R61k
PWM -1
ED
ED
L
L
D6
D7
0
0
47
47
1
0
1
1
R
R
LED2
LED3
E_FRONT
2
Q6
31
4
1
AIN
t
TC
N
RT14.7k/
V-
PWM-2
D
LE
8
D
470
R12
4
LED
2STR1215
z
3
33pF
Y1
16MH
C
T
EX
OSC_
R8
E_FRONT
DDV
1k
0
100nF
100nF
1
C
4
AIN8
AIN1
%)
1
k(
R184.7
VDD
1
2
1
X
2/4 Doc ID 18257 Rev 1