參數(shù)資料
型號(hào): R1221N49AD-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, 600 kHz SWITCHING FREQ-MAX, PDSO6
封裝: SOT-23, 6 PIN
文件頁數(shù): 7/21頁
文件大?。?/td> 218K
代理商: R1221N49AD-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.
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
R1221N49AE 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:Voltage-Mode SMPS Controller
R1221N49AE-TR 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:Voltage-Mode SMPS Controller
R1221N49AF 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:Voltage-Mode SMPS Controller
R1221N49AF-TR 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:Voltage-Mode SMPS Controller
R1221N49AG 制造商:RICOH 制造商全稱:RICOH electronics devices division 功能描述:Voltage-Mode SMPS Controller