參數(shù)資料
型號(hào)： LTC3112EDHD#TRPBF
廠商： LINEAR TECHNOLOGY CORP
元件分類： 穩(wěn)壓器
英文描述： 12 A SWITCHING REGULATOR, 825 kHz SWITCHING FREQ-MAX, PDSO16
封裝： 5 X 4 MM, 0.75 MM HEIGHT, LEAD FREE, PLASTIC, MO-229WJGD-2, DFN-16
文件頁(yè)數(shù)： 15/32頁(yè)
文件大?。?/td> 651K
代理商： LTC3112EDHD#TRPBF
LTC3112
22
3112f
then verify that sufcient phase margin exists across all
other operating conditions. In this example application, at
VIN = 3.5V and the full 1A load current, the right half plane
zero will be located at 60kHz and this will be a dominant
factor in determining the bandwidth of the control loop.
The rst step in designing the compensation network is
to determine the target crossover frequency for the com-
pensated loop. A reasonable starting point is to assume
that the compensation network will generate a peak phase
boost of approximately 60°. Therefore, in order to obtain
a phase margin of 60°, the loop crossover frequency, fC,
should be selected as the frequency at which the phase
of the buck-boost converter reaches 180°. As a result,
at the loop crossover frequency the total phase will be
simply the 60° of phase provided by the error amplier
as shown below.
Phase Margin =
φBUCK-BOOST + φERRORAMPLIFIER + 180°
= –180° + 60° + 180° = 60°
Similarly, if a phase margin of 45° is required, the target
crossover frequency should be picked as the frequency
at which the buck-boost converter phase reaches 195°
so that the combined phase at the crossover frequency
yields the desired 45° of phase margin.
This example will be designed for a 60° phase margin to
ensure adequate performance over parametric variations
and varying operating conditions. As a result, the target
crossover frequency, fC, will be the point at which the phase
of the buck-boost converter reaches 180°. It is generally
difcult to determine this frequency analytically given that
it is signicantly impacted by the Q factor of the resonance
in the power stage. As a result, it is best determined from a
Bode plot of the buck-boost converter as shown in Figure 9.
This Bode plot is for the LTC3112 buck-boost converter
using the previously specied power stage parameters
and was generated from the small signal model equations
using LTSpice. In this case, the phase reaches 180° at
35kHz making fC = 35kHz the target crossover frequency
for the compensated loop.
From the Bode plot of Figure 9 the gain of the power stage
at the target crossover frequency is 7dB. Therefore, in
order to make this frequency the crossover frequency
in the compensated loop, the total loop gain at fC must
be adjusted to 0dB. To achieve this, the gain of the
compensation network must be designed to be –7dB at
the crossover frequency.
At this point in the design process, there are three con-
straints that have been established for the compensation
network. It must have 7dB gain at fC= 35kHz, a peak phase
boost of 60° and the phase boost must be centered at
fC = 35kHz. One way to design a compensation network to
meet these targets is to simulate the compensated error
amplier Bode plot in LTSpice for the typical compensation
network shown on the front page of this datasheet. Then, the
gain,polefrequenciesandzerofrequenciescanbeiteratively
adjusted until the required constraints are met.
Alternatively, an analytical approach can be used to design
a compensation network with the desired phase boost,
center frequency and gain. In general, this procedure can
be cumbersome due to the large number of degrees of
freedom in a Type III compensation network. However the
design process can be simplied by assuming that both
compensation zeros occur at the same frequency, fZ, and
Figure 9. Converter Bode Plot, VIN = 3.5V, ILOAD = 1A
FREQUENCY (Hz)
10
GAIN
(dB)
PHASE
(DEG)
–150
–100
–50
0
10k
1M
3112 F09
–200
–250
100
1k
100k
50
–150
–100
–50
0
–200
–250
50
PHASE
fC
GAIN
APPLICATIONS INFORMATION
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LTC3112EFE#PBF 功能描述:IC REG BUCK BOOST SYNC 20-TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)關(guān)穩(wěn)壓器 系列:- 設(shè)計(jì)資源:Design Support Tool 標(biāo)準(zhǔn)包裝:1 系列:- 類型:升壓（升壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開(kāi)關(guān):- 電流 - 輸出:100mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-5 細(xì)型，TSOT-23-5 包裝:剪切帶 (CT) 供應(yīng)商設(shè)備封裝:TSOT-23-5 其它名稱:AS1323-BTTT-30CT
LTC3112EFE#PBF 制造商:Linear Technology 功能描述:IC DC-DC CONV 1.5MHz TSSOP20
LTC3112EFE#TRPBF 功能描述:IC REG BUCK BST SYNC ADJ 20TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)關(guān)穩(wěn)壓器 系列:- 設(shè)計(jì)資源:Design Support Tool 標(biāo)準(zhǔn)包裝:1 系列:- 類型:升壓（升壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開(kāi)關(guān):- 電流 - 輸出:100mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-5 細(xì)型，TSOT-23-5 包裝:剪切帶 (CT) 供應(yīng)商設(shè)備封裝:TSOT-23-5 其它名稱:AS1323-BTTT-30CT
LTC3112EFEPBF 制造商:Linear Technology 功能描述:15V 2.5A Synch Buck-Boost DC/DC TSSOP20
LTC3112IDHD#PBF 功能描述:IC REG BUCK BST SYNC ADJ 16-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)關(guān)穩(wěn)壓器 系列:- 設(shè)計(jì)資源:Design Support Tool 標(biāo)準(zhǔn)包裝:1 系列:- 類型:升壓（升壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開(kāi)關(guān):- 電流 - 輸出:100mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-5 細(xì)型，TSOT-23-5 包裝:剪切帶 (CT) 供應(yīng)商設(shè)備封裝:TSOT-23-5 其它名稱:AS1323-BTTT-30CT
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