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参数资料
| 型号： | LTC3822EMSE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 13/20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 selection of C OUT is driven by the effective series
resistance (ESR). Typically, once the ESR requirement
V OUT
is satis?ed, the capacitance is adequate for ?ltering. The
output ripple ( Δ V OUT ) is approximated by:
LTC3822
V FB
R B
C FF
≈ I RIPPLE ? ? ESR +
8 ? f ? C OUT ?
Δ V OUT
?
?
1 ?
?
R A
3822 F03
Figure 3. Setting the Output Voltage
where f is the operating frequency, C OUT is the output
capacitance and I RIPPLE is the ripple current in the induc-
tor. The output ripple is highest at maximum input voltage
since I RIPPLE increase with input voltage.
Top-Side MOSFET Drive Supply (C B , D B )
In the Functional Diagram, external bootstrap capacitor C B
is charged from a boost power source (usually V IN )
through diode D B when the SW node is low. When a
MOSFET is to be turned on, the C B voltage is applied
across the gate-source of the desired device. When the
top-side MOSFET is on, the BOOST pin voltage is above
the input supply. V BOOST = 2V IN . C B must be 100 times
the total input capacitance of the top-side MOSFET. The
reverse breakdown of D B must be greater than V IN(MAX) .
Figure 6 shows how a 5V gate drive can be achieved if a
Low Input Supply Voltage
Although the LTC3822 can function down to below 2.4V,
the maximum allowable output current is reduced as V IN
decreases below 3V. Figure 4 shows the amount of change
as the supply is reduced down to 2.4V. Also shown is the
effect on V REF .
Minimum On-Time Considerations
Minimum on-time, t ON(MIN) is the smallest amount of time
that the LTC3822 is capable of turning the top MOSFET on. It
is determined by internal timing delays and the gate charge
required to turn on the top MOSFET. Low duty cycle and
high frequency applications may approach the minimum
on-time limit and care should be taken to ensure that:
secondary 5V supply is available. Note that in applications
where the supply voltage to C B exceeds V IN , the BOOST
pin will draw approximately 500μA in shutdown mode.
t ON(MIN) <
V OUT
f OSC ? V IN
V OUT = 0.6V ? ? 1 + B ?
Setting Output Voltage
The LTC3822 output voltage is set by an external feed-
back resistor divider carefully placed across the output,
as shown in Figure 3. The regulated output voltage is
determined by:
? R ?
? R A ?
If the duty cycle falls below what can be accommodated
by the minimum on-time, the LTC3822 will begin to skip
cycles. The output voltage will continue to be regulated,
but the ripple current and ripple voltage will increase. The
minimum on-time for the LTC3822 is typically about 170ns.
However, as the peak sense voltage (I L(PEAK) ? R DS(ON) )
decreases, the minimum on-time gradually increases up
to about 260ns.
For most applications, a 59k resistor is suggested for R A .
In applications where minimizing the quiescent current is
critical, R A should be made bigger to limit the feedback
divider current. If R B then results in very high impedance,
it may be bene?cial to bypass R B with a 50pF to 100pF
capacitor C FF .
3822fa
13
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相关代理商/技术参数 |
参数描述 |
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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) |
| LTC3823EGN#TRPBF | 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) |
| LTC3823EUH#PBF | 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:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 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:8-TSSOP（0.173"，4.40mm 宽） 包装:带卷 (TR) |
| 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) |
| LTC3823IGN#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:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 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:8-TSSOP（0.173"，4.40mm 宽） 包装:带卷 (TR) |
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