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參數資料
| 型號： | R1221N48AC-TR |
| 廠商： | RICOH COMPANY LTD |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Voltage-Mode SMPS Controller |
| 中文描述： | 0.025 A SWITCHING CONTROLLER, 360 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封裝： | SOT-23, 6 PIN |
| 文件頁數： | 7/21頁 |
| 文件大小： | 218K |
| 代理商： | R1221N48AC-TR |
12345
Rev. 1.11 - 7 -
n
TYPICAL APPLICATIONS AND APPLICATION HINTS
Vcc
Reset/
CPU
EXT
V
IN
V
OUT
GND
VD
OUT
CE
SD1
L
C
OUT
C
IN
PMOS
R1
CE CONTROL
PMOS: HAT1020R (Hitachi), Si3443DV (Siliconix) L : CD105(Sumida, 27
m
H)
SD1 : RB491D (Rohm) C
OUT
: 47
m
F(Tantalum Type)
C
IN
:10
m
F(Tantalum Type) R1 : 100k
W
When you use these ICs, consider the following issues;
l
As shown in the block diagram, a parasitic diode is formed in each terminal, each of these diodes is not formed
for load current, therefore do not use it in such a way. When you control the CE pin by another power supply,
do not make its "H" level more than the voltage level of V
IN
pin.
l
Detector threshold hysteresis is set at 3 percent of detector threshold voltage. (Min. 1 percent, Max. 5 percent)
l
Setting Detector threshold voltage range depends on Output voltage of DC/DC converter.
Release Voltage from Reset condition must not be more than Output voltage of DC/DC converter.
(Detector Threshold Voltage
′
1.07 < Output Voltage of DC/DC converter
′
0.98
l
When the R1221NXXXX is on stand-by mode, the output voltage of VD
OUT
is GND level, therefore if the pull-up
resistor for VD
OUT
pin is pulled up another power supply, a certain amount of current is loading through the
resistor.
l
The operation of Latch-type protection circuit is as follows;
When the maximum duty cycle continues longer than the delay time for protection circuit, (Refer to the Electrical
Characteristics) the protection circuit works to shut-down the external Power MOS with its latching operation.
Therefore when an input/output voltage difference is small, the protection circuit may work even at small load
current.
To release the protection state, after disable this IC with a chip enable circuit, enable it again, or restart this IC
with power-on. However, in the case of restarting this IC with power-on, after the power supply is turned off, if
a certain amount of charge remains in C
IN
, or some voltage is forced to V
IN
from C
IN
, this IC might not be
restarted even after power-on.
If rising transition speed of supply voltage is too slow, or the time which is required for V
IN
voltage to reach
Output Voltage of DC/DC converter is longer than soft-starting time plus delay time for protection circuit,
protection circuit works before V
IN
voltage reaches Output Voltage of DC/DC converter. To avoid this condition,
make this IC disable(CE=”L”) first, then force V
IN
voltage, and after V
IN
voltage becomes equal or more than
V
OUT
, make this IC enable(CE=“H”).
l
Set external components as close as possible to the IC and minimize the connection between the components
and the IC. In particular, a capacitor should be connected to V
OUT
pin with the minimum connection. And make
sufficient grounding and reinforce supplying. A large switching current flows through the connection of power
supply, an inductor and the connection of V
OUT.
If the impedance of power supply line is high, the voltage level of
power supply of the IC fluctuates with the switching current. This may cause unstable operation of the IC.
相關PDF資料 |
PDF描述 |
|---|---|
| R1221N48AD | Voltage-Mode SMPS Controller |
| R1221N48AD-TR | Voltage-Mode SMPS Controller |
| R1221N48AE | Voltage-Mode SMPS Controller |
| R1221N48AE-TR | Voltage-Mode SMPS Controller |
| R1221N48AF | Voltage-Mode SMPS Controller |
相關代理商/技術參數 |
參數描述 |
|---|---|
| R1221N48AD | 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:Voltage-Mode SMPS Controller |
| R1221N48AD-TR | 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:Voltage-Mode SMPS Controller |
| R1221N48AE | 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:Voltage-Mode SMPS Controller |
| R1221N48AE-TR | 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:Voltage-Mode SMPS Controller |
| R1221N48AF | 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:Voltage-Mode SMPS Controller |
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