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| 型号： | LTC1871EMS |
| 厂商： | Linear Technology |
| 文件页数： | 20/36页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST FLYBK CM 10MSOP |
| 标准包装： | 50 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1MHz |
| 占空比： | 97% |
| 电源电压： | 2.5 V ~ 36 V |
| 降压： | 无 |
| 升压： | 是 |
| 回扫： | 是 |
| 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： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 管件 |
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LTC1871
APPLICATIONS INFORMATION
I O(MAX)
P R(WINDING) = ? R W
I O(MAX)
P FET = ? R DS(ON) ? D MAX ? T
+ k ? V O1.85 ?
( 1– D MAX )
thenoff,apacketofgatechargeQ G istransferredfrom
INTV CC to ground. The resulting dQ/dt is a current that
must be supplied to the INTV CC capacitor through the
V IN pin by an external supply. If the IC is operating in
CCM:
I Q(TOT) ≈ I Q = f ? Q G
P IC = V IN ? (I Q + f ? Q G )
2. Power MOSFET switching and conduction losses. The
technique of using the voltage drop across the power
MOSFET to close the current feedback loop was chosen
because of the increased ef?ciency that results from
not having a sense resistor. The losses in the power
MOSFET are equal to:
2
1– D MAX
I O(MAX)
? C RSS ? f
The I 2 R power savings that result from not having a
discrete sense resistor can be calculated almost by
3. The losses in the inductor are simply the DC input cur-
rent squared times the winding resistance. Expressing
this loss as a function of the output current yields:
2
1– D MAX
4. Losses in the boost diode. The power dissipation in the
boost diode is:
P DIODE = I O(MAX) ? V D
The boost diode can be a major source of power loss
in a boost converter. For the 3.3V input, 5V output at
7A example given above, a Schottky diode with a 0.4V
forward voltage would dissipate 2.8W, which represents
7% of the input power. Diode losses can become signi?-
cant at low output voltages where the forward voltage
is a signi?cant percentage of the output voltage.
5. Other losses, including C IN and C O ESR dissipation and
inductor core losses, generally account for less than
2% of the total additional loss.
Checking Transient Response
inspection.
P R(SENSE) =
I O(MAX)
1– D MAX
2
? R SENSE ? D MAX
The regulator loop response can be veri?ed by looking at
the load transient response. Switching regulators generally
take several cycles to respond to an instantaneous step
in resistive load current. When the load step occurs, V O
To understand the magnitude of the improvement with
this V DS sensing technique, consider the 3.3V input,
5V output power supply shown in Figure 1. The maxi-
mum load current is 7A (10A peak) and the duty cycle
is 39%. Assuming a ripple current of 40%, the peak
inductor current is 13.8A and the average is 11.5A.
With a maximum sense voltage of about 140mV, the
immediately shifts by an amount equal to ( Δ I LOAD )(ESR),
and then C O begins to charge or discharge (depending on
the direction of the load step) as shown in Figure 13. The
regulator feedback loop acts on the resulting error amp
output signal to return V O to its steady-state value. During
this recovery time, V O can be monitored for overshoot or
ringing that would indicate a stability problem.
sense resistor value would be 10mΩ, and the power
dissipated in this resistor would be 514mW at maxi-
mum output current. Assuming an ef?ciency of 90%,
this sense resistor power dissipation represents 1.3%
of the overall input power. In other words, for this ap-
plication, the use of V DS sensing would increase the
ef?ciency by approximately 1.3%.
For more details regarding the various terms in these
I OUT
2V/DIV
V OUT (AC)
100mV/DIV
V IN = 3.3V
V OUT = 5V
MODE/SYNC = INTV CC
(PULSE-SKIP MODE)
equations, please refer to the section Boost Converter:
100μs/DIV
1871 F13
Power MOSFET Selection.
Figure 13. Load Transient Response for a 3.3V Input,
5V Output Boost Converter Application, 0.7A to 7A Step
1871fe
20
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1871EMS#PBF | 功能描述:IC REG CTRLR BST FLYBK CM 10MSOP 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 |
| LTC1871EMS#TR | 功能描述:IC REG CTRLR BST FLYBK CM 10MSOP RoHS:否 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) |
| LTC1871EMS#TRPBF | 功能描述:IC REG CTRLR BST FLYBK CM 10MSOP 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) |
| LTC1871EMS-1#PBF | 功能描述:IC REG CTRLR BST FLYBK CM 10MSOP 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) |
| LTC1871EMS-1#TRPBF | 功能描述:IC REG CTRLR BST FLYBK CM 10MSOP 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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