Rohm BD71631QWZ-EVK-001, Руководство пользователя

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© 2021 ROHM Co., Ltd.
No. 64UG016E Rev.001
MAY.2021
User’s Guide
BD71631QWZ-EVK-001
Charge current
[mA]
I
CHG
NTC Temp [ ]
48
2
Hys Hys
7
43
Figure 7. Charge Current vs Battery Temperature
NTC terminal voltage(V
NTC_Cold
、
V
NTC_Hot
)
2 °C: 3.605 V
7 °C: 3.375 V
43 °C: 1.720 V
48 °C: 1.535 V
Figure 8. Resistor setting of NTC terminal
How to find the external resistance of the NTC terminal and the NCT constant is as follows.
When calculating RNTC and RNTCR1, firstly calculate the resistance voltage dividers V
Hot
and V
Cold
when charging stops with the
NTC thermistor temperature profile in Figure 7. The error of the %V
Cold
and %V
Hot
thresholds will depend on temperature
coefficient B of the chosen NTC thermistor resistor.
By simulated calculation, the resistance value is calculated so that the error of the NTC terminal voltage at each temperature
becomes small.
𝑉
𝐶𝑜𝑙𝑑
= (
𝑅𝑁𝑇𝐶_𝑐𝑜𝑙𝑑
𝑅𝑁𝑇𝐶1 + 𝑅𝑁𝑇𝐶_𝑐𝑜𝑙𝑑
) × 𝑉𝐼𝑁 [𝑉]
𝑉
𝐻𝑜𝑡
= (
𝑅𝑁𝑇𝐶_𝐻𝑜𝑡
𝑅𝑁𝑇𝐶1 + 𝑅𝑁𝑇𝐶_𝐻𝑜𝑡
) × 𝑉𝐼𝑁 [𝑉]
%𝑉
𝐶𝑜𝑙𝑑
=
𝑉
𝐶𝑜𝑙𝑑
𝑉
𝑁𝑇𝐶_𝐶𝑜𝑙𝑑
%𝑉
𝐻𝑜𝑡
=
𝑉
𝐻𝑜𝑡
𝑉
𝑁𝑇𝐶_𝐻𝑜𝑡
Battery
NTC
T
V
IN
= 5 V
10 k
Ω
NCP03XH103F05RL
10 k
Ω
/ B(25 /50 ) = 3380k
RNTC
RNTC1
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