参数资料
| 型号： | LTC3813EG#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 24/32页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST PWM CM 28-SSOP |
| 标准包装： | 47 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1MHz |
| 电源电压： | 7 V ~ 75 V |
| 降压： | 无 |
| 升压： | 是 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 28-SSOP（0.209"，5.30mm 宽） |
| 包装： | 管件 |
| 产品目录页面： | 1336 (CN2011-ZH PDF) |
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LTC3813
APPLICATIONS INFORMATION
the appropriate parasitic values are known, simulated or
generated from the modulator transfer function. Mea-
surement will give more accurate results, but simulation
or transfer function can often get close enough to give
a working system. To measure the modulator gain and
phase directly, wire up a breadboard with an LTC3813
and the actual MOSFETs, inductor and input and output
capacitors that the ?nal design will use. This breadboard
should use appropriate construction techniques for high
speed analog circuitry: bypass capacitors located close
to the LTC3813, no long wires connecting components,
appropriately sized ground returns, etc. Wire the feedback
ampli?er with a 0.1μF feedback capacitor from I TH to FB
and a 10k to 100k resistor from V OUT to FB. Choose the
bias resistor (R B ) as required to set the desired output
voltage. Disconnect R B from ground and connect it to
a signal generator or to the source output of a network
analyzer to inject a test signal into the loop. Measure the
gain and phase from the I TH pin to the output node at the
positive terminal of the output capacitor. Make sure the
analyzer’s input is AC coupled so that the DC voltages
present at both the I TH and V OUT nodes do not corrupt
the measurements or damage the analyzer.
If breadboard measurement is not practical, mathemat-
ical software such as MATHCAD or MATLAB can be used
to generate plots from the transfer function given in
equation 1. A SPICE simulation can also be used to gener-
ate approximate gain/phase curves. Plug the expected
capacitor, inductor and MOSFET values into the following
SPICE deck and generate an AC plot of V OUT / V ITH with gain
in dB and phase in degrees. Refer to your SPICE manual
for details of how to generate this plot.
*This ? le simulates a simpli ? ed model of
the LTC3813 for generating a v(out)/(vith)
or a v(out)/v(outin) bode plot
.param rdson=0.02
.param Vrng=1
.param vsnsmax={0.173*Vrng-0.026}
.param K={vsnsmax/rdson/1.2}
.param wz={1/esr/cout}
.param wp={2/rload/cout}
*
* Feedback Ampli ? er
rfb1 outin vfb 29k
rfb2 vfb 0 1k
eithx ithx 0 laplace {0.8-v(vfb)} =
{1/(1+s/1000)}
eith ith 0 value={limit(1e6*v(ithx),0,2.4)}
cc1 ith vfb 100p
cc2 ith x1 0.01 μ
rc x1 vfb 100k
*
* Modulator/Output Stage
eout out 0 laplace {v(ith)} =
{0.5*K*Rload*vin/vout *(1+s/wz)/(1+s/wp)
*(1-s*L/Rload*vout*vout/vin/vin)}
rload out 0 {rload}
*
vstim out outin dc=0 ac=10m; ac stimulus
.ac dec 100 10 10meg
.probe
.end
With the gain/phase plot in hand, a loop crossover fre-
quency can be chosen. Usually the curves look something
like Figure 10. Choose the crossover frequency about 25%
of the switching frequency for maximum bandwidth. Al-
though it may be tempting to go beyond f SW /4, remember
that signi?cant phase shift occurs at half the switching
frequency that isn’t modeled in the above H(s) equation
and PSPICE code. Note the gain (GAIN, in dB) and phase
(PHASE, in degrees) at this point. The desired feedback
.param
.param
.param
.param
.param
.param
*
vout=24
vin=12
L=10u
cout=270u
esr=.018
rload=24
ampli?er gain will be –GAIN to make the loop gain at 0dB
at this frequency. Now calculate the needed phase boost,
assuming 60° as a target phase margin:
BOOST = – (PHASE + 30°)
If the required BOOST is less than 60°, a Type 2 loop can
be used successfully, saving two external components.
BOOST values greater than 60° usually require Type 3
loops for satisfactory performance.
3813fb
24
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| LTC3813IG#PBF | 功能描述:IC REG CTRLR BST PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3813IG#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3814EFE-5#PBF | 功能描述:IC REG CTRLR BST PWM CM 16-TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| LTC3814EFE-5#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 16-TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
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