MD3221N 查看數據表（PDF） - Shindengen
零件编号
产品描述 (功能)
比赛名单
MD3221N Datasheet PDF : 26 Pages
| |||
↓Click!
5 Functions
◆Setting the Output Voltage
MD3221N output voltage may be set between 0.8V
and 14V. When set to 2.5V or 3.3V the internal
dividing resistor is used and an external resistor is not
required. Output voltage is set with a minimum
accuracy of ±3%.
● Wiring for 2.5V Output
L1
VOUT 11~14
+V0
OCL+ 25
MD3221N
OCL- 27
2.5V/3.3V 31
−
0.8V
＋
ampIN
30
amp-
29
● Wiring for 3.3V Output
R 5 ＝ 1k［Ω］
R4＝
R
5
×（VO−
0.8
0.8
）［Ω］
VO：Output voltage［V］
As the reference voltage has a minimum accuracy
of ±2%. The accuracy of the set output voltage is
determined by the accuracy of the reference
voltages and the accuracy of the resistor.
● Wiring for Variable Output
L1
11~14
VOUT
MD3221N
amp-
−
29
＋
0.8V
+V0
R4
R5
L1
VOUT 11~14
+V0
OCL+ 25
MD3221N
OCL- 27
2.5V/3.3V 31
−
0.8V
＋
ampIN
30
amp-
29
◆Selecting the Oscillation Frequency
The MD3221N incorporates an internal oscillator, and
an external C.R is therefore not required. The
oscillation frequency may be set to either 100kHz or
300kHz.
The internal dividing resistor is connected across the
OCL and GND pins, with the dividing point
connected to the ampIN pin. The ampIN pin should
therefore be connected to the amp- pin externally.
An external dividing resistor is required if output
voltage is to be set to other than 2.5V or 3.3V. As the
error amp reference voltage is 0.8V the value for the
dividing resistor is determined with the equation
below.
Switching losses in switching power supplies generally
increase as the oscillation frequency increases,
however the MD3221N is designed to provide
sufficiently high efficiency at 300kHz. Furthermore,
the number of peripheral components (eg the inductor)
is minimized, and thus a standard circuit using the
300kHz frequency provides benefits in terms of both cost
and space. Use of the 100kHz frequency is effective in
terms of reducing high-frequency noise, and is more
effective than the 300kHz frequency at low-load at
which switching losses dominate.
10
Share Link: 