参数资料
| 型号： | ADP3050AR-3.3 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 14/20页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK 3.3V 1A 8SOIC |
| 标准包装： | 98 |
| 类型： | 降压（降压） |
| 输出类型： | 固定 |
| 输出数： | 1 |
| 输出电压： | 3.3V |
| 输入电压： | 3.6 V ~ 30 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 200kHz |
| 电流 - 输出： | 1A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
| 供应商设备封装： | 8-SO |
| 配用： | ADP3050-EVAL-ND - BOARD EVAL FOR ADP3050 |
ADP3050
Choosing a Catch Diode
Use the following steps to pick an appropriate catch diode.
voltage and forward current ratings.
The average diode current rating must be sufficient to provide
the required load current (see the calculations in the previous
section). Diodes rated below 1 A should not be used, even if the
average diode current is much lower.
The reverse voltage rating of the catch diode should be at least the
maximum input voltage. Often a higher rating is chosen
(1.2× the maximum input voltage) to provide a safety margin.
Data Sheet
DISCONTINOUS MODE RINGING
When operating in discontinuous mode, high frequency
ringing appears at the switch node when the inductor current
has decreased to zero. This ringing is normal and is not a result
of loop instability. It is caused by the switch and diode capacitance
reacting with the inductor to form a damped sinusoidal ringing.
This ringing is usually in the range of several megahertz, and is
not harmful to normal circuit operation.
SETTING THE OUTPUT VOLTAGE
The fixed voltage versions of the ADP3050 (3.3 V and 5 V) have
the feedback resistor divider included on-chip. For the adjustable
R2 = R1 × ? OUT ? 1 ?
? V ?
Table 5. Schottky Diode Selection Guide
V R 1A 2A
15 V 10BQ15 30BQ15
20 V 1N5817 B220
30 V V1N5818 B230
40 V 1N5819 B240
3A
SK32
SK33
SK34
version, the output voltage is set using two external resistors.
Referring to Figure 25, pick a value for R1 between 10 kΩ and
20 kΩ, then calculate the appropriate value for R2 using the
following equation:
(9)
? 1 . 20 ?
INPUT CAPACITOR SELECTION
The input bypass capacitor plays an important role in proper
regulator operation, minimizing voltage transients at the input
and providing a short local loop for the switching current. Place
this capacitor close to the ADP3050 between the IN and GND
pins using short, wide traces. This input capacitor should have
an rms ripple current rating of at least
It is important to note that the accuracy of these resistors
directly affects the accuracy of the output voltage. The FB pin
threshold variation is ±3%, and the tolerances of R1 and R2 add
to this to determine the total output variation. Use 1% resistors
placed close to the FB pin to prevent noise pickup.
FREQUENCY COMPENSATION
The ADP3050 uses a unique compensation scheme that allows
? ? ? OUT
?
?
I CIN ( RMS ) ≥ I OUT ×
V OUT
V IN
? V
? V IN
?
?
2
(8)
the use of any type of output capacitor. The designer is not
limited to a specific type of capacitor or a specific ESR range.
External compensation allows the designer to optimize the loop
This rating is crucial because the input capacitor must be able to
withstand the large current pulses present at the input of a step-
down regulator. Values of 20 μF to 50 μF are typical, but the
main criteria for capacitor selection is the ripple current and
voltage ratings.
Ceramics are an excellent choice for input bypassing, due to
their low ESR and high ripple current rating. Ceramics are
especially suited for high input voltages and are available from
many different manufacturers. Tantalums are often used for
input bypassing, but precautions must be taken because they
occasionally fail when subjected to large inrush currents during
power-up. These surges are common when the regulator input
is connected to a battery or high capacitance supply. Several
manufacturers now offer surface-mount solid tantalum capacitors
that are surge tested, but even these devices can fail if the current
surge occurs when the capacitor voltage is near its maximum
rating. For this reason, a 2:1 derating is suggested for tantalum
capacitors used in applications where large inrush currents are
present. For example, a 20 V tantalum should be used only for
an input voltage up to 10 V. Aluminum electrolytics are the
cheapest choice, but it takes several in parallel to get a good rms
current rating. OS-CON capacitors have a good ESR and ripple
current rating, but they are typically larger and more costly.
Refer to Table 4 for a list of capacitor manufacturers.
for transient response and system performance. The values for
R C and C C set the pole and zero locations for the error amplifier
to compensate the regulator loop.
For tantalum output capacitors, the typical system compensation
values are R C = 4 kΩ and C C = 1 nF; for ceramics, the typical
values are R C = 4 kΩ and C C = 4.7 nF. These values may not be
optimized for all designs, but they provide a good starting point for
selecting the final compensation values. Other types of output
capacitors require different values of C C between 0.5 nF and 10 nF.
Typically, the lower the ESR of the output capacitor, the larger
the value for C C . Normal variations in capacitor ESR, output
capacitance, and inductor value (due to production tolerances,
changes in operating point, changes in temperature) affect the
loop gain and phase response. Always check the final design
over its complete operating range to ensure proper regulator
operation.
Adjusting the R C and C C values can optimize compensation. Use
the typical values above as a starting point, then try increasing
and decreasing each independently and observing the transient
response. An easy way to check the transient response of the
design is to observe the output while pulsing the load current at
a rate of approximately 100 Hz to 1 kHz. There should be some
slight ringing at the output when the load pulses, but this should
not be excessive (just a few rings). The frequency of this ringing
Rev. C | Page 14 of 20
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADP3050AR-5 | 制造商:Analog Devices 功能描述:Conv DC-DC Single Step Down 3.6V to 30V 8-Pin SOIC N 制造商:Rochester Electronics LLC 功能描述:HIGH VOLTAGE STEP DOWN SWITCHING REG. - Bulk 制造商:Analog Devices 功能描述:IC SWITCHING REGULATOR |
| ADP3050AR-5-REEL | 制造商:Analog Devices 功能描述:Conv DC-DC Single Step Down 3.6V to 30V 8-Pin SOIC N T/R |
| ADP3050AR-5-REEL7 | 制造商:Analog Devices 功能描述:Conv DC-DC Single Step Down 3.6V to 30V 8-Pin SOIC N T/R 制造商:Analog Devices 功能描述:ANAADP3050AR-5-REEL7 HI VOLT SWCH REG |
| ADP3050AR-REEL | 制造商:Analog Devices 功能描述:Conv DC-DC Single Step Down 3.6V to 30V 8-Pin SOIC N T/R |
| ADP3050AR-REEL7 | 制造商:Analog Devices 功能描述:Conv DC-DC Single Step Down 3.6V to 30V 8-Pin SOIC N T/R 制造商:Rochester Electronics LLC 功能描述:- Tape and Reel |
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