R1224N122G RICOH [RICOH electronics devices division], R1224N122G Datasheet - Page 11

• Manufacturer Part Number: R1224N122G
• Description: PWM/VFM step-down DC/DC Converter
• Manufacturer: RICOH [RICOH electronics devices division]

In the continuous mode, when Equation 1 is solved for ton and assumed that the solution is tonc,
When ton<tonc, the mode is the discontinuous mode, and when ton=tonc, the mode is the continuous mode.
OUTPUT CURRENT AND SELECTION OF EXTERNAL COMPONENTS
When Lx Tr. is ON:
(Wherein, Ripple Current P-P value is described as I
current of the inductor is described as R
When Lx Tr. is OFF:
Put Equation 4 to Equation 3 and solve for ON duty, ton/(toff+ton)=D
Ripple Current is as follows;
Wherein, peak current that flows through L, Lx Tr., and SD is as follows;
Consider ILmax, condition of input and output and select external components.
tonc=T×V
V
L×I
D
I
ILmax=I
The above explanation is directed to the calculation in an ideal case in continuous mode.
RP
IN
ON
=(V
=V
RP
=(V
/toff=V
OUT
IN
OUT
−V
OUT
+(Rp+RL)×I
OUT
+V
OUT
+I
F
+V
/V
F
RP
−Rp×I
+R
IN
/2............................................................................ Equation 7
OUT
..................................................................................... Equation 2
L
×I
+R
OUT
OUT
OUT
L
×I
−R
)/(V
+L×I
OUT
L
×I
IN
............................................................ Equation 4
+V
RP
OUT
/ton .................................................Equation 3
F
)×D
−Rp×I
ON
/f/L........................................Equation 6
OUT
L
.)
) ......................................Equation 5
RP
, ON resistance of Lx Tr. is described as Rp the direct
ON
,
R1224N
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