HM4033 データシートの表示（PDF） - Unspecified
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HM4033 Datasheet PDF : 9 Pages
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HM4033
lower limit, the external N-channel MOSFET is turned on again, and a new cycle starts. Battery voltage is
feedback to FB pin via the external resistor divider, when the voltage at FB pin rises to 1.205V(Typical), the
charging is terminated, the external N-channel MOSFET remains off until the voltage at FB pin decreases to
recharge threshold, which will make HM4033 enter charge status again. The maximum switching frequency of
HM4033 can be up to 1MHz.
Application Information
About Input Voltage Range
HM4033 operates from a 4V to 28V input voltage. When the input voltage is between 4V to 5.5V, the voltage at
VCC pin may be less than 5V, though HM4033 can function correctly.
5V Voltage Regulator
VCC is the output of a 5V regulator capable of sourcing 5mA. Bypass VCC to GND with a 4.7μF to 10μF
capacitor.
Inductor Current (Input Current)
In the application circuit shown in Figure 1, HM4033 sets the inductor current through a current sense resistor
RCS connected between VIN and CSN pin.
When the external N-channel MOSFET is turned on, inductor current rises, when inductor current rises to:
ILhigh = 0.15V / RCS
The external N-channel MOSFET is turned off, inductor current falls, and the energy is transferred to the battery
and the output capacitor. When inductor current falls to:
ILlow = 0.12V / RCS
The external N-channel MOSFET is turned on again, and a new cycle begins.
So, average inductor current is:
IL = 0.135V / RCS
In the above 3 equations, ILhigh is upper limit of inductor current in ampere(A)
ILlow is lower limit of inductor current in ampere(A)
RCS is current sense resistor in ohm(Ω)
Calculate Switching Frequency and Duty Cycle
In the application circuit shown in Figure 1，the on-time of external N-channel MOSFET is:
The off-time of external N-channel MOSFET is:
Switching frequency is:
Duty cycle is:
In the above 4 equations, L is inductor value in Henry(H)
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