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参数资料
| 型号： | ADP3050-BL1-EVZ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 18/20页 |
| 文件大小： | 0K |
| 描述： | BOARD EVALUATION FOR ADP3050 |
| 标准包装： | 1 |
| 系列： | * |
I RIPPLE =
12 1 ? 5
47 × 10 ? 6
ADP3050
INVERTING (BUCK BOOST) REGULATOR
The circuit in Figure 29 shows the ADP3050 in a buck-boost
configuration that produces a negative output voltage from a
positive input voltage. This topology looks quite similar to the
buck shown in Figure 28 (except the IC and the output filter are
now referenced to the negative output instead of ground), but
its operation is quite different. For this topology, the feedback
pin is grounded and the GND pin is tied to the negative output,
allowing the feedback network of the IC to regulate the negative
output voltage.
Data Sheet
For the circuit in Figure 29, the maximum ripple current (at the
maximum input voltage) is
× × = 0 . 375 A
200 × 10 3 12 + ? 5
High ripple currents are present in both the input and output
capacitors, and their ripple current ratings must be large
enough to sustain the large switching currents present in this
topology. The capacitors should have a ripple current rating of
at least
L1
47μH
D2
1N4148
C5
100μF
+
I RMS ( C IN , C OUT ) ≈ I OUT ×
V OUT
V IN
(20)
C3
0.22μF
1
2
SWITCH IN 8
BOOST GND 7
The peak current seen by the diode, switch, and inductor is
found by rearranging the load current equation
? V IN + V OUT
1
× I OUT ? + ? ? × I RIPPLE ? ?
I PEAK = ?
(21)
? ? 2
V IN
?
?
D1
1N5818
3
4
BIAS SD 6
FB COMP 5
U1
ADP3050-5
R1
5.1k?
C4
3.3nF
V OUT
?
? ?
The largest peak currents occur at the lowest input voltage. For
this design with a load current of 500 mA
I PEAK = ? ?
× 0 . 5 ? ? + ? ? × 0 . 375 ? ? = 0 . 9 A
SD
12V
V IN
+ C1
C2
–5V AT 0.5A
? 12 + ? 5
? 12
? 1
? ? 2 ?
(22)
GND
22μF
0.01μF
The average current diode is equal to the load current.
I OUT ( MAX ) =
V IN
(18)
V IN × V OUT
(
)
? I SW ( MAX ) ? ?
Figure 29. Inverting (Buck-Boost) Regulator
The design procedure used for the standard buck converter
cannot be used for a buck-boost converter due to fundamental
differences in how the output voltage is generated. The switch
currents in the buck-boost are much higher than the standard
buck converter, thus lowering the available load current. To
calculate the maximum output current for a given maximum
switch current, use the following equation:
×
V IN + V OUT
? ?
? ?
? 2 × f SW × L × V IN + V OUT ?
where I SW(MAX) is the switch current limit rating of the ADP3050,
and V IN is the minimum input voltage. The inductor ripple
current is estimated using the following equation:
An inductor with a current rating 20% greater than 0.9 A
should be used (a rating of at least 1.2 A). Inductors and diodes
with ratings greater than 1 A should always be used, even if
the calculated peak and average currents are lower. This ensures
that start-up and fault conditions do not overstress the
components.
For the buck-boost topology, the input voltage can be less than
the output voltage, such as V IN = 4 V or V OUT = ?5 V, but the
available load current is even lower. The equations given in this
section are valid for input voltages less than and greater than
the output voltage. The voltage seen by the ADP3050 is equal to
the sum of the input and output voltages (the BOOST pin sees
the sum of V IN + 2 × |V OUT |). It is important to ensure that the
maximum voltage rating of these pins is not exceeded.
I RIPPLE =
V IN ( MAX )
L
×
1
f SW
×
V OUT
V IN ( MAX ) + V OUT
(19)
Rev. C | Page 18 of 20
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADP3050-EVAL | 功能描述:BOARD EVAL FOR ADP3050 RoHS:否 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:- 标准包装:1 系列:- 主要目的:DC/DC，步降 输出及类型:1，非隔离 功率 - 输出:- 输出电压:3.3V 电流 - 输出:3A 输入电压:4.5 V ~ 28 V 稳压器拓扑结构:降压 频率 - 开关:250kHz 板类型:完全填充 已供物品:板 已用 IC / 零件:L7981 其它名称:497-12113STEVAL-ISA094V1-ND |
| ADP3050-EVALZ | 制造商:AD 制造商全称:Analog Devices 功能描述:200 kHz, 1 A High Voltage Step-Down Switching Regulator |
| ADP3051 | 制造商:AD 制造商全称:Analog Devices 功能描述:500 mA PWM Step-Down DC-DC with Synchronous Rectifier |
| ADP3051ARMZ-REEL | 制造商:Analog Devices 功能描述:CONV DC-DC SGL-OUT STEP DOWN 8MSOP - Tape and Reel |
| ADP3051ARMZ-REEL7 | 制造商:Analog Devices 功能描述:Conv DC-DC Single Step Down 2.7V to 5.5V 8-Pin MSOP T/R 制造商:Analog Devices 功能描述:SWITCH REG SYNC BUCK 500MA 8MSOP |
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