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参数资料
| 型号： | LTC3822EMSE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/20页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 10-MSOP |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 850kHz |
| 占空比： | 99% |
| 电源电压： | 2.75 V ~ 4.5 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 ~ 85°C |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 |
| 包装： | 带卷 (TR) |
LTC3822
APPLICATIONS INFORMATION
The typical LTC3822 application circuit is shown on the
front page of this data sheet. External component selection
for the controller is driven by the load requirement and
begins with the selection of the inductor and the power
MOSFETs.
where I RIPPLE is the inductor peak-to-peak ripple current
(see Inductor Value Calculation).
A reasonable starting point is setting ripple current I RIPPLE
to be 40% of I OUT(MAX) . Rearranging the above equation
yields:
5 Δ V SENSE(MAX)
Power MOSFET Selection
The LTC3822’s controller requires external N-channel
R DS(ON)MAX =
?
6 I OUT(MAX)
for Duty Cycle < 20%
power MOSFETs for the topside (main) and bottom
(synchronous) switches. The main selection criteria for
the power MOSFETs are the breakdown voltage V BR(DSS) ,
threshold voltage V GS(TH) , on-resistance R DS(ON) , reverse
transfer capacitance C RSS , turn-off delay t D(OFF) and the
However, for operation above 20% duty cycle, slope
compensation has to be taken into consideration to select
the appropriate value of R DS(ON) to provide the required
amount of load current:
total gate charge Q G .
The gate drive voltage is usually the input supply voltage.
R DS(ON)MAX =
5
6
? SF ?
Δ V SENSE(MAX)
I OUT(MAX)
See Figure 7 for an application with a higher gate drive
voltage. Since the LTC3822 is designed for operation at
low input voltages, a sublogic level MOSFET (R DS(ON)
guaranteed at V GS = 2.5V) is required.
The topside MOSFET’s on-resistance is chosen based on
the required load current. The maximum average load
current I OUT(MAX) is equal to the peak inductor current
minus half the peak-to-peak ripple current I RIPPLE . The
LTC3822’s current comparator monitors the drain-to-
where SF is a scale factor whose value is obtained from
the curve in Figure 1.
These must be further derated to take into account the
signi?cant variation in on-resistance with temperature.
The following equation is a good guide for determining the
required R DS(ON)MAX at 25°C (manufacturer’s speci?ca-
tion), allowing some margin for variations in the LTC3822
and external component values:
source voltage V DS of the top MOSFET, which is sensed
between the V IN and SW pins. The peak inductor current
is limited by the current threshold, set by the voltage on
R DS(ON)MAX =
5
6
? 0.9 ? SF ?
Δ V SENSE(MAX)
I OUT(MAX) ? ρ T
the I TH pin, of the current comparator. The voltage on the
I TH pin is internally clamped, which limits the maximum
current sense threshold Δ V SENSE(MAX) to approximately
120mV when IPRG is ?oating (82mV when IPRG is tied
low; 200mV when IPRG is tied high).
The output current that the LTC3822 can provide is given
by:
The ρ T is a normalizing term accounting for the tempera-
ture variation in on-resistance, which is typically about
0.4%/°C, as shown in Figure 2. Junction-to-case tem-
perature Δ T JC is about 10°C in most applications. For a
maximum ambient temperature of 70°C, using ρ 80°C ~ 1.3
in the above equation is a reasonable choice.
– RIPPLE
I OUT(MAX) =
Δ V SENSE(MAX)
R DS(ON)
I
2
3822fa
10
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| LTC3823EGN#PBF | 功能描述:IC REG CTRLR BUCK 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: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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| LTC3823EUH#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN 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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