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参数资料
| 型号： | LTC3704EMS#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 15/28页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR INV PWM CM 10-MSOP |
| 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： | 无 |
| 回扫： | 无 |
| 反相： | 是 |
| 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 |
| 产品目录页面： | 1335 (CN2011-ZH PDF) |
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LTC3704
APPLICATIO S I FOR ATIO
the initial equations for I L1(PEAK) and I L2(PEAK) . If a coupled
inductor is used, make sure that the minimum saturation
current for the parallel configuration exceeds the maxi-
mum switch current, or:
Power MOSFET or Sense Resistor Selection
If the maximum voltage on the drain of the power MOSFET
(which is V IN(MAX) + V OUT , plus any transients) is less than
36V then the circuit can take advantage of the LTC3704’s
I LSAT ( MIN ) ≥ – ? 1 +
? ? I O ( MAX ) ?
?
?
χ ?
2 ?
1
1 – D MAX
No R SENSE technology in order to improve efficiency and
eliminate the sense resistor. For higher switch voltages
the SENSE pin should be connected to a resistor in the
The saturation current rating should be checked at mini-
mum input voltage (which results in the highest average
inductor current) and maximum load current.
Operating in Discontinuous Mode
Discontinuous mode operation occurs when the load
current is low enough to allow the inductor current to run
source of the power MOSFET, as shown in Figure 2.
Internal leading-edge blanking is provided in the LTC3704
to eliminate the need for filtering components on the
SENSE pin.
In both positive-to-negative and flyback converters the
maximum switch current is equal to the input current plus
the output current. As a result, the peak switch current is:
I SW ( PEAK ) = – ? 1 +
? ? I O ( MAX ) ?
out during the off-time of the switch, as shown in
Figure 10. Once the inductor current is near zero, the
switch and diode capacitances resonate with the induc-
?
?
χ ?
2 ?
1
1 – D MAX
tance to form damped ringing at 1MHz to 10MHz. If the
off-time is long enough, the drain voltage will settle to the
input voltage.
Depending on the input voltage and the residual energy in
the inductor, this ringing can cause the drain of the power
MOSFET to go below ground where it is clamped by the
body diode. This ringing is not harmful to the IC and it has
not been shown to contribute significantly to EMI. Any
where I O(MAX) is a negative number.
During the switch on-time, the control circuit limits the
maximum voltage drop across the power MOSFET to
150mV (at low duty cycles). The peak switch current is
therefore limited to 150mV/R DS(ON) . The relationship be-
tween the maximum load current, the duty cycle and the
R DS(ON) of the power MOSFET is:
attempt to damp it with a snubber will degrade the efficiency.
R DS ( ON ) ≤
V SENSE(MAX)
I SW ( PEAK )
? 1 + ? ? I O ( MAX ) ? ρ Τ
V DS
10V/DIV
or
R DS ( ON ) ≤ V SENSE ( MAX ) ?
? χ ?
? 2 ?
D MAX ? 1
I L1
1A/DIV
V IN = 15V 1 μ s/DIV 3704 F10
NO LOAD
Figure 10. Discontinuous Mode Waveforms
(MODE/SYNC = INTV CC , Pulse-Skip Mode)
for the Circuit in Figure 1.
again, where I O(MAX) is a negative number. The V SENSE(MAX)
term is typically 150mV at low duty cycle, and is reduced
to about 100mV at a duty cycle of 92% due to slope
compensation, as shown in Figure 11. The ρ Τ term ac-
counts for the temperature coefficient of the R DS(ON) of the
MOSFET, which is typically 0.4%/ ° C. Figure 12 illustrates
the variation of R DS(ON) over temperature for a typical
power MOSFET (normalized for simplicity).
3704fb
15
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3704IMS | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Pos-Neg 2.5V to 36V Input 10-Pin MSOP |
| LTC3704IMS#PBF | 功能描述:IC REG CTRLR INV PWM CM 10-MSOP 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) |
| LTC3704IMS#TR | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Pos-Neg 2.5V to 36V Input 10-Pin MSOP T/R |
| LTC3704IMS#TRPBF | 功能描述:IC REG CTRLR INV PWM CM 10-MSOP 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) |
| LTC3705EGN#PBF | 功能描述:IC CTRLR OCP 16SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - AC-DC 转换器，离线开关 系列:- 标准包装:3,000 系列:- 输出隔离:隔离 频率范围:61kHz ~ 71kHz 输入电压:9.4 V ~ 28 V 输出电压:12V 功率（瓦特）:- 工作温度:-40°C ~ 125°C 封装/外壳:SC-74，SOT-457 供应商设备封装:6-TSOP 包装:带卷 (TR) |
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