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參數(shù)資料
| 型號： | R1211N002A |
| 廠商： | Ricoh Co., Ltd. |
| 英文描述： | Step-up DC/DC Controller |
| 中文描述： | 升壓DC / DC控制器 |
| 文件頁數(shù)： | 12/33頁 |
| 文件大小： | 375K |
| 代理商： | R1211N002A |
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Rev. 1.10 - 12 -
continuous. The continuous current through the inductor is described as Iconst, then,
I
OUT
= f
OSC
×
V
IN
2
×
t
ON
2
/(2
×
L
×
(V
OUT
-V
IN
))+V
IN
×
Iconst/V
OUT
Formula 6
In this moment, the peak current, ILxmax flowing through the inductor and the driver Tr. is described as follows:
ILxmax = Iconst +V
IN
×
Ton/L
Formula 7
With the formula 4,6, and ILxmax is,
ILxmax = V
OUT
/V
IN
×
I
OUT
+V
IN
×
Ton/(2
×
L)
Formula 8
Therefore, peak current is more than I
OUT
. Considering the value of ILxmax, the condition of input and output, and
external components should be selected.
In the formula 7, peak current ILxmax at discontinuous mode can be calculated. Put Iconst=0 in the formula.
The explanation above is based on the ideal calculation, and the loss caused by Lx switch and external components
is not included. The actual maximum output current is between 50% and 80% of the calculation. Especially, when the
ILx is large, or V
IN
is low, the loss of V
IN
is generated with the on resistance of the switch. As for V
OUT,
Vf (as much as
0.3V) of the diode should be considered.
I
TIMING CHART
G
R1211X002A/R1211X002C
EXT
V
OUT
SS
VREF
PWM Comparator
OP AMP
V
FB
AMPOUT
DTC
R1
R2
EXT
G
R1211X002B/R1211X002D
EXT
V
OUT
SS
VREF
PWM Comparator
OP AMP
V
FB
AMPOUT
DTC
R1
R2
EXT
<Soft-start Operation>
Soft-start operation is starting from power-on as follows:
(Step1)
The voltage level of SS is rising gradually by constant current circuit of the IC and a capacitor. V
REF
level which is
input to OP AMP is also gradually rising. V
OUT
is rising up to input voltage level just after the power-on, therefore, V
FB
voltage is rising up to the setting voltage with input voltage and the ration of R1 and R2. AMPOUT is at “L”, and
switching does not start.
(Step2)
相關PDF資料 |
PDF描述 |
|---|---|
| R1211N002A-TR | Step-up DC/DC Controller |
| R1211N002C | Step-up DC/DC Controller |
| R1211N002C-TR | Step-up DC/DC Controller |
| R1211N002D | Step-up DC/DC Controller |
| R1211N002D-TR | Step-up DC/DC Controller |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| R1211N002A_06 | 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:STEP-UP DC/DC CONTROLLER |
| R1211N002A-TR | 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:Step-up DC/DC Controller |
| R1211N002B | 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:STEP-UP DC/DC CONTROLLER |
| R1211N002B-TR | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog IC |
| R1211N002C | 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:STEP-UP DC/DC CONTROLLER |
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