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参数资料
| 型号： | LT3844EFE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/24页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST INV PWM 16TSSOP |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 330kHz |
| 占空比： | 95% |
| 电源电压： | 4 V ~ 60 V |
| 降压： | 是 |
| 升压： | 是 |
| 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 ~ 125°C |
| 封装/外壳： | 16-TSSOP（0.173"，4.40mm）裸露焊盘 |
| 包装： | 带卷 (TR) |
LT3844
APPLICATIONS INFORMATION
Therefore, the peak inductor current is 100mV/R SENSE .
The maximum output load current, I OUT(MAX) , is the peak
inductor current minus half the peak-to-peak ripple cur-
rent, Δ I L .
Allowing adequate margin for ripple current and exter-
nal component tolerances, R SENSE can be calculated as
follows:
for operating frequency is that in noise-sensitive com-
munications systems, it is often desirable to keep the
switching noise out of a sensitive frequency band. The
LT3844 uses a constant frequency architecture that can
be programmed over a 100kHz to 500kHz range with a
single resistor from the f SET pin to ground, as shown in
Figure 1. The nominal voltage on the f SET pin is 1V and
the current that ?ows from this pin is used to charge an
R SENSE =
70 mV
I OUT ( MAX )
internal oscillator capacitor. The value of R SET for a given
operating frequency can be chosen from Figure 4 or from
the following equation:
Typical values for R SENSE are in the range of 0.005Ω to
0.05Ω.
Operating Frequency
R SET ( k Ω ) = 8 . 4 ? 10 4 ? f SW (– 1 . 31 )
Table 1 lists typical resistor values for common operating
frequencies:
The choice of operating frequency and inductor value is
a trade off between ef?ciency and component size. Low
frequency operation improves ef?ciency by reducing
MOSFET switching losses and gate charge losses. However,
lower frequency operation requires more inductance for a
given amount of ripple current, resulting in a larger induc-
tor size and higher cost. If the ripple current is allowed
to increase, larger output capacitors may be required to
maintain the same output ripple. For converters with high
step-down V IN -to-V OUT ratios, another consideration is
the minimum on-time of the LT3844 (see the Minimum
On-time Considerations section). A ?nal consideration
Table 1. Recommended 1% Standard Values
R SET
191kΩ
118kΩ
80.6kΩ
63.4kΩ
49.9kΩ
40.2kΩ
33.2kΩ
27.4kΩ
23.2kΩ
f SW
100kHz
150kHz
200kHz
250kHz
300kHz
350kHz
400kHz
450kHz
500kHz
200
180
160
140
120
100
80
Step-Down Converter: Inductor Selection
The critical parameters for selection of an inductor are
minimum inductance value, volt-second product, satura-
tion current and/or RMS current.
For a given Δ I, The minimum inductance value is calculated
as follows:
60
40
20
L ≥ V OUT ?
V IN ( MAX ) – V OUT
f SW ? V IN ( MAX ) ? Δ I L
0
100
200
300
400
500
600
FREQUENCY (kHz)
3844 G19
f SW is the switch frequency.
Figure 1. Timing Resistor (R SET ) Value
3844fb
11
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| LT3844IFE | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Step Down 4V to 60V Input 16-Pin TSSOP EP |
| LT3844IFE#PBF | 功能描述:IC REG CTRLR BST INV PWM 16TSSOP 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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| LT3844IFEPBF | 制造商:Linear Technology 功能描述:DC-DC Controller Step-Down 4-60V TSSOP16 |
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