MB39A214APFT-G-JNERE1 Datasheet, PDF (26/56 Pages) Fujitsu Component Limited. – 2ch DC/DC converter IC with PFM/ PWM synchronous rectification

MB39A214A
„ APPLICATION NOTE
1. Setting Operating Conditions
Setting output voltages
The output voltage can be set by adjusting the setting output voltage resistor ratio. Setting output voltage is
calculated by the following formula.
V_OUTx = ^{R1 + R2} ¯ (0.6946 + 0.2667¯ΔI_L¯ (1− ^2.8¯10-7 ) ¯R_{ON_Sync}) + ^ΔVOUTx
R2
t_OFF
2
ΔV_OUTx = ESR ¯ΔI_L, ΔI_L =
V_IN − V_{OUT ¯}
L
V_OUT
V_IN ¯ f_OSC
, ^tOFF ⁼
(V_IN − V_OUTx)
V_IN¯f_OSC
V_OUTx
V_IN
ΔV_OUTX
t_OFF
R_{ON_Sync}
ΔI_L
ESR
L
f_OSC
: Output setting voltage [V]
: Power supply voltage [V]
: Output ripple voltage value [V]
: Off time [s]
: ON resistance of low-side FET [Ω]
: Ripple current peak-to-peak value of inductor [A]
: Series resistance element of output capacitor [Ω]
: Inductor value [H]
: Switching frequency [Hz]
VOUTx
R1
R2
VOUTX
FBX
x: Each channel number
The total resistor value (R1+R2) of the setting output resistor should be selected up to 100 kΩ.
26
DS405-00007-1v0-E