- 您现在的位置：买卖IC网 > PDF目录15320 > LTC3809EMSE#TRPBF (Linear Technology)IC REG CTRLR BUCK PWM CM 10-MSOP PDF资料下载
参数资料
| 型号： | LTC3809EMSE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 14/24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： | 825kHz |
| 占空比： | 100% |
| 电源电压： | 2.75 V ~ 9.8 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) |
LTC3809
APPLICATIONS INFORMATION
that do not work well at high input voltages (e.g., V IN >
5V) may work ?ne at lower voltages (e.g., 3.3V).
Selecting the N-channel MOSFET is typically easier, since
for a given R DS(ON) , the gate charge and turn-on and turn-off
delays are much smaller than for a P-channel MOSFET.
A reasonable starting point is to choose a ripple current
that is about 40% of I OUT(MAX) . Note that the largest ripple
current occurs at the highest input voltage. To guarantee
that ripple current does not exceed a speci?ed maximum,
the inductor should be chosen according to:
? OUT
Operating Frequency and Synchronization
L ≥
V IN – V OUT
f OSC ? I RIPPLE
V
V IN
The choice of operating frequency, f OSC , is a trade-off
between ef ?ciency and component size. Low frequency
operation improves ef ?ciency by reducing MOSFET
switching losses, both gate charge loss and transition
loss. However, lower frequency operation requires more
inductance for a given amount of ripple current.
Burst Mode Operation Considerations
The choice of R DS(ON) and inductor value also determines
the load current at which the LTC3809 enters Burst Mode
operation. When bursting, the controller clamps the peak
inductor current to approximately:
The internal oscillator for the LTC3809’s controller runs
at a nominal 550kHz frequency when the PLLLPF pin is
left ?oating and the SYNC/MODE pin is not con?gured
I BURST ( PEAK ) =
1 Δ V SENSE(MAX )
?
4 R DS ( ON )
for spread spectrum operation. Pulling the PLLLPF to
V IN selects 750kHz operation; pulling the PLLLPF to GND
selects 300kHz operation.
Alternatively, the LTC3809 will phase-lock to a clock
signal applied to the SYNC/MODE pin with a frequency
between 250kHz and 750kHz (see Phase-Locked Loop
and Frequency Synchronization).
To further reduce EMI, the nominal 550kHz frequency will
be spread over a range with frequencies between 460kHz
The corresponding average current depends on the
amount of ripple current. Lower inductor values (higher
I RIPPLE ) will reduce the load current at which Burst Mode
operation begins.
The ripple current is normally set so that the inductor cur-
rent is continuous during the burst periods. Therefore,
I RIPPLE ≤ I BURST(PEAK)
This implies a minimum inductance of:
? OUT
and635kHzwhenspreadspectrummodulationisenabled
(see Spread Spectrum Modulation with SYNC/MODE and
PLLLPF Pins).
L MIN ≤
V IN – V OUT
f OSC ? I BURST ( PEAK )
V
V IN
Inductor Value Calculation
Given the desired input and output voltages, the inductor
value and operating frequency, f OSC , directly determine
the inductor’s peak-to-peak ripple current:
A smaller value than L MIN could be used in the circuit,
although the inductor current will not be continuous
during burst periods, which will result in slightly lower
ef ?ciency. In general, though, it is a good idea to keep
I RIPPLE comparable to I BURST(PEAK) .
V OUT V IN – V OUT
I RIPPLE =
V IN f OSC ? L
?
Inductor Core Selection
Once the value of L is known, the type of inductor must
Lower ripple current reduces core losses in the inductor,
ESR losses in the output capacitors and output voltage
ripple. Thus, highest ef ?ciency operation is obtained at
low frequency with a small ripple current. Achieving this,
be selected. High ef ?ciency converters generally cannot
afford the core loss found in low cost powdered iron cores,
forcing the use of more expensive ferrite, molypermalloy
or Kool Mμ ? cores. Actual core loss is independent of core
however, requires a large inductor.
3809fc
14
相关PDF资料 |
PDF描述 |
|---|---|
| GEM30DTMT-S189 | CONN EDGECARD 60POS R/A .156 SLD |
| LTC3850EUFD#TRPBF | IC REG CTRLR BUCK PWM CM 28-QFN |
| LT1737CS#PBF | IC REG CTRLR FLYBK ISO CM 16SOIC |
| H2ABT-10103-R8-ND | JUMPER-H1502TR/A3048R/H1500TR 3" |
| RCM28DCWI | CONN EDGECARD 56POS DIP .156 SLD |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3809IDD-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 10-DFN 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) |
| LTC3809IDD-1#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 10-DFN 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) |
| LTC3809IMSE-1#PBF | 功能描述:IC REG CTRLR BUCK 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) |
| LTC3809IMSE-1#TRPBF | 功能描述:IC REG CTRLR BUCK 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) |
| LTC3810EG#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:- 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 |
发布紧急采购，3分钟左右您将得到回复。