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参数资料
| 型号： | TC115301EMT |
| 元件分类： | 稳压器 |
| 英文描述： | 0.4 A SWITCHING REGULATOR, 115 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封装： | SOT-89, 5 PIN |
| 文件页数： | 8/12页 |
| 文件大小： | 148K |
| 代理商： | TC115301EMT |
5
TC115
PFM/PWM Step-up DC/DC Converter
TC115-1 4/26/99
2001 Microchip Technology Inc.
DS21361A
The inductor value directly affects the output ripple
voltage. Equation 3 is derived as shown below, and can be
used to calculate an inductor value, given the required
output ripple voltage (VRIPPLE) and output capacitor series
resistance:
VRIPPLE ≈ ESR(di)
where ESR is the equivalent series resistance of the
output filter capacitor, and VRIPPLE is in volts.
Expressing di in terms of switch ON resistance and time:
Solving for L:
Care must be taken to ensure the inductor can handle
peak switching currents, which can be several times load
currents. Exceeding rated peak current will result in core
saturation and loss of inductance. The inductor should be
selected to withstand currents greater than IPK (Equation 10)
without saturating.
Calculating the peak inductor current is straightforward.
Inductor current consists of an AC (sawtooth) current cen-
tered on an average DC current (i.e. input current). Equation
6 calculates the average DC current. Note that minimum
input voltage and maximum load current values should be
used:
Re-writing in terms of input and output currents and
voltages:
Solving for input curent:
The sawtooth current is centered on the DC current
level; swinging equally above and below the DC current
calculated in Equation 6. The peak inductor current is the
sum of the DC current plus half the AC current. Note that
minimum input voltage should be used when calculating the
AC inductor current (Equation 9).
where: VSW = VCESAT of the switch (note if a CMOS
switch is used to substitute VCESAT with RDSON x IIN)
Combining the DC current calculated in Equation 6, with
half the peak AC current calculated in Equation 9, the peak
inductor current is given by:
IPK = IIN(MAX) + 0.5(di)
Internal Transistor Switch
The LX pin has a typical ON resistance of 1.4
, there-
fore peak switch current is given by (VIN/1.4). The internal
transistor switch has a maximum design rating of 350 mA.
An oscillator frequency doubling circuit is an included guard
against high switching currents. Should the voltage on the
LX pin rise above 1.3V, max, while the internal N-channel
switch is ON, the oscillator frequency automatically doubles
to minimize ON time. Although reduced, switch current still
flows because the PWM remains in operation.
Therefore,
the LX input is not internally current limited and care must be
taken never to exceed the 350 mA maximum limit. Failure
to observe this will result in damage to the regulator.
Equation 1.
Equation 2.
Equation 3.
Equation 4.
Equation 5.
Equation 6.
Equation 7.
Equation 8.
Equation 9.
Equation 10.
VRIPPLE ≈
ESR [(VIN – VSW)tON]
L
Input Power = Output Power
Efficiency
IIN(MAX) =
(VOUT(MAX))(IOUT(MAX))
(Efficiency)(VIN(MIN))
di =
V(dt)
L
V = L(di)
dt
(VIN(MIN)) (IN(MAX)) =
(VOUT(MAX))(IOUT(MAX))
Efficiency
di =
[(VIN(MIN) – VSW)tON]
L
≈
ESR [(VIN – VSW)tON]
VRIPPLE
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TC115301EMTTR | 功能描述:开关变换器、稳压器与控制器 PFM/PWM Step-Up RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| TC115331ECT | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:PFM/PWM Step-Up DC/DC Converter |
| TC115331EMTTR | 功能描述:开关变换器、稳压器与控制器 PFM/PWM Step-Up RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| TC115501ECT | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:PFM/PWM Step-Up DC/DC Converter |
| TC115501EMTTR | 功能描述:开关变换器、稳压器与控制器 PFM/PWM Step-Up RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
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