MM1333J データシートの表示（PDF） - Mitsumi

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MM1333J

Control for Lithium Ion Battery Charging (one cell)

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Control for Lithium Ion Battery Charging (one cell) MM1333

5. R5 and R6 are resistors for positive feedback (hysteresis). Hysteresis is applied for the amount of R5

voltage drop, and should be set below (about 1/3) full charge voltage.

Also, at this time, full charge detection voltage changes by the amount of R5 voltage drop.

Example : Setting full charge detection current using H rank and taking hysteresis voltage into account.

Setting conditions : charge current 0.25A (R3 + R4=0.4Ω), full charge current 0.1A, MPU power supply 5V,

full charge hysteresis 10mV

Full charge current is set by comparing the reference voltage (VIC=0.031V) and CS2 pin voltage (V2) inside

the IC. An example of calculation for setting full charge current at 0.1A is shown below.

(V2-V1)+IBATT R4=0.031V

Here, V2-V1 (potential at ends of R5) is the hysteresis. In order to set hysteresis at 10mV, find R4 as

follows.

R4=(0.031V-(V2-V1)/IBATT=(0.031V-0.01V)/0.1A = 0.21Ω

From R3 + R4 = 0.4Ω, R3 = 0.4Ω-0.21Ω = 0.19Ω.

Hysteresis Setting (R5 ~ R7)

The current values that flow on R5~R7 from 3V are minute due to the high impedance of the CS2 pin, and

so do not cause a problem. (It is assumed that the effects of noise, etc. must be considered for each

individual set.) Here the setting is for 10µA. CO is low level during full charge detection, so V2-V1 = 0V.

When V2-V1 is set to 10mV during charging (CO high), then R5 + R6 + R7 = 3V/10µA = 300kW. (R4 is

extremely small as compared to R5~R7 and thus is ignored.)

3V : 0.01V=(R5 + R6 + R7) : R5

From the above equation, R5 = 1kΩ, R6 + R7 = 299kΩ, and R6 and R7 resistance values must be set so

that CS1 can be low level. If CS1 sink current is 0.15mA, then R7 = 3V/0.15mA=20kΩ, R6=299kΩ-20kΩ =

279kΩ.

Therefore, R3 = 0.19Ω, R4 = 0.21Ω, R5 = 1kΩ, R6 = 279kΩ, R7 = 20kΩ.

Please note that the above figures are examples given for reference purposes, and should be used in actual

practice only after sufficient examination.

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