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参数资料
| 型号： | LTC3722IGN-1#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 20/28页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR DIV ISO PWM 24SSOP |
| 标准包装： | 55 |
| PWM 型： | 电流模式，全桥 |
| 输出数： | 1 |
| 频率 - 最大： | 1MHz |
| 占空比： | 98.5% |
| 电源电压： | 3.8 V ~ 10.3 V |
| 降压： | 无 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 是 |
| Cuk： | 无 |
| 隔离： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 24-SSOP（0.154"，3.90mm 宽） |
| 包装： | 管件 |
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LTC3722-1/LTC3722-2
OPERATION
R CS =
I P (PEAK) =
I O(MAX) V IN(MAX) ? D MIN
N P
N S
output current for the converter can be delivered at the
lowest expected V IN . Use the following formula to calculate
the optimal value for R CS . I P equation valid for current
doubler secondary.
LTC3722-1:
300m V – (82.5μA ? R SLOPE )
I P (PEAK)
+ +
2 ? N ? EFF L MAG ? f CLK ? 2
V O (1 – D MIN )
L OUT ? f CLK ? N
where : N = Transformer turns ratio =
LTC3722-2:
The advantage of the high side location is a greater im-
munity to leading edge noise spikes, since gate charge
current and reflected rectifier recovery current are largely
eliminated. Figure 11 illustrates a typical current sense
transformer based sensing scheme. R S in this case is
calculated the same as in the resistive case, only its value
is increased by the sense transformer turns ratio. At high
duty cycles, it may become difficult or impossible to re-
set the current transformer. This is because the required
transformer reset voltage increases as the available time
for reset decreases to equalize the (volt ? seconds) applied.
The interwinding capacitance and secondary inductance of
the current sense transformer form a resonant circuit that
limits the dV/dT on the secondary of the CS transformer.
This, in turn, limits the maximum achievable duty cycle for
the CS transformer. Attempts to operate beyond this limit
will cause the transformer core to “walk” and eventually
saturate, opening up the current feedback loop.
Common methods to address this limitation include:
R CS =
300mV
I P (PEAK)
1. Reducing the maximum duty cycle by lowering the
power transformer turns ratio.
2. Reducing the switching frequency of the converter.
R SLOPE
R S
CurrentTransformerSensing
A current sense transformer can be used in lieu of resistive
sensing with the LTC3722-1/LTC3722-2. Current sense
transformers are available in many styles from several
manufacturers. A typical sense transformer for this ap-
plication will use a 1:50 turns ratio (N), so that the sense
resistor value is N times larger, and the secondary current
N times smaller than in the resistive sense case. Therefore,
the sense resistor power loss is about N times less with
the transformer method, neglecting the transformers core
and copper losses. The disadvantages of this approach
include, higher cost and complexity, lower accuracy,
core reset/maximum duty cycle limitations and lower
speed. Nevertheless, for very high power applications,
this method is preferred. The sense transformer primary
is placed in the same location as the ground referenced
sense resistor, or between the upper MOSFET drains in
the (MA, MC) and V IN .
3. Employ external active reset circuitry.
4. Using two CS transformers summed together.
5. Choose a CS transformer optimized for high frequency
applications.
MB MD
SOURCE SOURCE
N:1
RAMP
CURRENT
TRANSFORMER
CS
OPTIONAL
FILTERING 372212 F11
Figure 11. Current Transformer Sense Circuitry
372212fb
20
For more information www.linear.com/LTC3722
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| LTC3722IGN-2#PBF | 功能描述:IC REG CTRLR DIV ISO PWM 24SSOP 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 |
| LTC3722IGN-2#TRPBF | 功能描述:IC REG CTRLR DIV ISO PWM 24SSOP 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 |
| LTC3723EGN-1 | 功能描述:IC REG CTRLR FLYBK ISO CM 16SSOP 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: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 |
| LTC3723EGN-1#2EYPBF | 制造商:Linear Technology 功能描述: |
| LTC3723EGN-1#PBF | 功能描述:IC REG CTRLR FLYBK ISO CM 16SSOP 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 |
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