Rohm BD71631QWZ-EVK-001, User Manual

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© 2021 ROHM Co., Ltd.
No. 64UG016E Rev.001
MAY.2021
User’s Guide
BD71631QWZ-EVK-001
Peripheral Components Setting
1.
Charging voltage (V
CHG
), Recharge voltage (V
RECHG
) setting
The resistance values of the charging voltage V
CHG
and re-charge voltage V
RECHG
can be set by the following formula.
Battery
VOUT
VFBG
VFB
VFBRE
RFB1
RFB2
RFBRE1
V
CHG
RFBRE2
CSPU
V
RECHG
,
Figure 5. Resistor setting of V
CHG
and V
RECHG
The charge voltage is determined as follows :
𝑉
𝐶𝐻𝐺
= (𝑅𝐹𝐵1 + 𝑅𝐹𝐵2) 𝑅𝐹𝐵2
⁄
× 0.6 [𝑉]
The re-charge voltage is determined as follows :
𝑉
𝑅𝐸𝐶𝐻𝐺
= (𝑅𝐹𝐵𝑅𝐸1 + 𝑅𝐹𝐵𝑅𝐸2) 𝑅𝐹𝐵𝑅𝐸2
⁄
× 0.6 [𝑉]
About total feedback resistance, the following is a reference example of operation settings. .
Table 4. Resister reference value
Charge
Condition
V
CHG
= 4.2 V V
CHG
= 2.2 V V
CHG
= 4.2 V
V
RECHG
= 3.0V V
RECHG
= Disenable V
RECHG
= 3.9 V
Resistor value [Ω]
RFB1 180 k 200 k 600 k
RFB2 30 k 75 k 100 k
RFBRE1 120 k -* 1.1 M
RFBRE2 30 k -* 200 k
*VFBRE pin connect to GND
A capacity of 10μF or more is required between the VOUT terminal and GND terminal of BD71631QWZ. Connect C
SPU
for
stable operation when the battery capacity is too small.
The capacitance of C
SPU
is determined as follows :
𝐶
𝑆𝑃𝑈
= 1 (2𝜋 × 300 × 𝑅𝐹𝐵1) [𝐹] ⁄
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