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参数资料
| 型号： | LTC3203EDD#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BST SWITCHD CAP ADJ 10DFN |
| 标准包装： | 2,500 |
| 类型： | 升压（升压），切换电容（充电泵） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 可调 |
| 输入电压： | 2.7 V ~ 5.5 V |
| PWM 型： | Burst Mode? |
| 频率 - 开关： | 900kHz，1MHz |
| 电流 - 输出： | 500mA |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-WFDFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 10-DFN（3x3） |
LTC3203/LTC3203-1
LTC3203B/LTC3203B-1
APPLICATIO S I FOR ATIO
Power Efficiency
V OUT
2
The power efficiency ( η ) of the LTC3203/LTC3203-1/
LTC3203B/LTC3203B-1 in 1.5x mode is similar to that of
a linear regulator with an effective input voltage of 1.5
LTC3203/
LTC3203B
FB
GND
5
9, 11
C FB
R1
R2
C OUT
3203 F01
times the actual input voltage. This occurs because the
input current for a 1.5x fractional charge pump is approxi-
mately 1.5 times the load current. In an ideal regulating
1.5x charge pump the power efficiency would be given by:
Figure 1. Programming the LTC3203/LTC3203B Output Voltage
The voltage divider ratio is given by the expression:
= OUT ? 1 or V OUT = ?
+ 1 ? ? 0 . 91 V
η 1 . 5 XIdeal =
P OUT
P IN
=
V OUT ? I OUT
V IN ? 1 . 5 I OUT
=
V OUT
1 . 5 V IN
R 1 V ? R 1
R 2 0 . 91 V ? R 2
?
?
Similarly, in 2x mode, the efficiency is similar to that of a
linear regulator with an effective input voltage of twice the
actual input voltage. In an ideal regulating voltage doubler
the power efficiency would be given by:
Typical values for total voltage divider resistance can
range from several k ? s up to 1M ? . The compensation
capacitor (C FB ) is necessary to counteract the pole caused
by the large valued resistors R1 and R2, and the input
= OUT OUT = OUT
η 2 XIdeal =
P OUT
P IN
V ? I V
V IN ? 2 I OUT 2 V IN
capacitance of the FB pin. For best results, C FB should be
5pF for all R1 or R2 greater than 10k and can be omitted
if both R1 and R2 are less than 10k.
At moderate to high output power the switching losses
and quiescent current of the LTC3203/LTC3203-1/
LTC3203B/LTC3203B-1 are negligible and the expression
above is valid.
As evident from the above two equations, with the same
V IN , the 1.5x mode will give higher efficiency than the
2x mode.
The LTC3203/LTC3203B can also be configured to control
a current. In white LED applications the LED current is
programmed by the ratio of the feedback set point voltage
and a sense resistor as shown in Figure 2. The current of
the remaining LEDs is controlled by virtue of their similar-
ity to the reference LED and the ballast voltage across the
sense resistor.
Programming the LTC3203/LTC3203B Output Voltage
(FB Pin)
V OUT
2
I LED =
V FB
R X
While the LTC3203-1/LTC3203B-1 have internal resistive
dividers to program the output voltage, the programmable
LTC3203/
LTC3203B
FB
5
???
LTC3203/LTC3203B may be set to an arbitrary voltage via
an external resistive divider. Since it operates as a voltage
GND
9, 11
C OUT
R X
R X
doubling charge pump when MODE is less than V MODEL ,
it is not possible to achieve output voltages greater than
twice the available input voltage in this case. Similarly,
when MODE is greater than V MODEH , the achievable output
voltage is less than 1.5 times the available input voltage.
Figure 1 shows the required voltage divider connection.
3203 F02
Figure 2. Programming the LTC3203/LTC3203B Output Current
In this configuration the feedback factor ( ? V OUT / ? I OUT )
will be very near unity since the small signal LED imped-
ance will be considerably less than the current setting
32031fa
10
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相关代理商/技术参数 |
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|---|---|
| LTC3204 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Low Noise Regulated Charge Pump in 2 X 2 DFN |
| LTC3204-3.3 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Low Noise Regulated Charge Pump in 2 X 2 DFN |
| LTC3204-5 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Low Noise Regulated Charge Pump in 2 X 2 DFN |
| LTC3204B-3.3 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Low Noise Regulated Charge Pump in 2 X 2 DFN |
| LTC3204B-5 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Low Noise Regulated Charge Pump in 2 X 2 DFN |
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