- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄385567 > MC34166 (ON SEMICONDUCTOR) 500kHz and 1MHz High Efficiency 1.5A Switching Regulators; Package: SO; No of Pins: 8; Temperature Range: -40?°C to 85?°C PDF資料下載
參數(shù)資料
| 型號(hào)： | MC34166 |
| 廠商： | ON SEMICONDUCTOR |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | 500kHz and 1MHz High Efficiency 1.5A Switching Regulators; Package: SO; No of Pins: 8; Temperature Range: -40?°C to 85?°C |
| 中文描述： | 射頻放大器 |
| 文件頁數(shù)： | 7/18頁 |
| 文件大?。?/td> | 265K |
| 代理商： | MC34166 |
MC34166, MC33166
http://onsemi.com
7
INTRODUCTION
The MC34166, MC33166 series are monolithic power
switching regulators that are optimized for dctodc
converter applications. These devices operate as fixed
frequency, voltage mode regulators containing all the active
functions required to directly implement stepdown and
voltageinverting converters with a minimum number of
external components. They can also be used cost effectively
in stepup converter applications. Potential markets include
automotive, computer, industrial, and cost sensitive
consumer products. A description of each section of the
device is given below with the representative block diagram
shown in Figure 14.
Oscillator
The oscillator frequency is internally programmed to
72 kHz by capacitor C
T
and a trimmed current source. The
charge to discharge ratio is controlled to yield a 95%
maximum duty cycle at the Switch Output. During the
discharge of C
T
, the oscillator generates an internal blanking
pulse that holds the inverting input of the AND gate high,
disabling the output switch transistor. The nominal oscillator
peak and valley thresholds are 4.1 V and 2.3 V respectively.
Pulse Width Modulator
The Pulse Width Modulator consists of a comparator with
the oscillator ramp voltage applied to the noninverting input,
while the error amplifier output is applied into the inverting
input. Output switch conduction is initiated when C
T
is
discharged to the oscillator valley voltage. As C
T
charges to
a voltage that exceeds the error amplifier output, the latch
resets, terminating output transistor conduction for the
duration of the oscillator rampup period. This PWM/Latch
combination prevents multiple output pulses during a given
oscillator clock cycle. Figures 7 and 15 illustrate the switch
output duty cycle versus the compensation voltage.
Current Sense
The MC34166 series utilizes cyclebycycle current
limiting as a means of protecting the output switch transistor
from overstress. Each oncycle is treated as a separate
situation. Current limiting is implemented by monitoring the
output switch transistor current buildup during conduction, and
upon sensing an overcurrent condition, immediately turning
off the switch for the duration of the oscillator rampup period.
The collector current is converted to a voltage by an internal
trimmed resistor and compared against a reference by the
Current Sense comparator. When the current limit threshold is
reached, the comparator resets the PWM latch. The current
limit threshold is typically set at 4.3 A. Figure 10 illustrates
switch output current limit threshold versus temperature.
Error Amplifier and Reference
A high gain Error Amplifier is provided with access to the
inverting input and output. This amplifier features a typical dc
voltage gain of 80 dB, and a unity gain bandwidth of 600 kHz
with 70 degrees of phase margin (Figure 4). The noninverting
input is biased to the internal 5.05 V reference and is not
pinned out. The reference has an accuracy of
±
2.0% at room
temperature. To provide 5.0 V at the load, the reference is
programmed 50 mV above 5.0 V to compensate for a 1.0%
voltage drop in the cable and connector from the converter
output. If the converter design requires an output voltage
greater than 5.05 V, resistor R
1
must be added to form a
divider network at the feedback input as shown in Figures 14
and 19. The equation for determining the output voltage with
the divider network is:
Vout
5.05
R2
R1
1
External loop compensation is required for converter
stability. A simple lowpass filter is formed by connecting a
resistor (R
2
) from the regulated output to the inverting input,
and a series resistorcapacitor (R
F
, C
F
) between Pins 1 and 5.
The compensation network component values shown in each
of the applications circuits were selected to provide stability
over the tested operating conditions. The stepdown converter
(Figure 19) is the easiest to compensate for stability. The
stepup (Figure 21) and voltageinverting (Figure 23)
configurations operate as continuous conduction flyback
converters, and are more difficult to compensate. The simplest
way to optimize the compensation network is to observe the
response of the output voltage to a step load change, while
adjusting R
F
and C
F
for critical damping. The final circuit
should be verified for stability under four boundary conditions.
These conditions are minimum and maximum input voltages,
with minimum and maximum loads.
By clamping the voltage on the error amplifier output
(Pin 5) to less than 150 mV, the internal circuitry will be
placed into a low power standby mode, reducing the power
supply current to 36 A with a 12 V supply voltage. Figure 11
illustrates the standby supply current versus supply voltage.
The Error Amplifier output has a 100 A current source
pullup that can be used to implement softstart. Figure 18
shows the current source charging capacitor C
SS
through a
series diode. The diode disconnects C
SS
from the feedback
loop when the 1.0 M resistor charges it above the operating
range of Pin 5.
Switch Output
The output transistor is designed to switch a maximum of
40 V, with a minimum peak collector current of 3.3 A. When
configured for stepdown or voltageinverting applications, as
in Figures 19 and 23, the inductor will forward bias the output
rectifier when the switch turns off. Rectifiers with a high
forward voltage drop or long turnon delay time should not be
used. If the emitter is allowed to go sufficiently negative,
collector current will flow, causing additional device heating
and reduced conversion efficiency. Figure 9 shows that by
clamping the emitter to 0.5 V, the collector current will be in
the range of 100 A over temperature. A 1N5822 or
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MC34167 | 500kHz and 1MHz High Efficiency 1.5A Switching Regulators; Package: SO; No of Pins: 8; Temperature Range: -40?°C to 85?°C |
| MC34262D | POWER FACTOR CONTROLLERS |
| MC34262P | POWER FACTOR CONTROLLERS |
| MC34262 | Power Factor Controllers(功率因數(shù)控制器) |
| MC34280 | Power Supply & Management IC for Handheld Electronic Products(用于手提電子產(chǎn)品的電源管理芯片) |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MC34166_05 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:3.0 A, Step−Up/Down/Inverting Switching Regulators |
| MC34166D2T | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 40V 3A RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| MC34166D2TG | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 40V 3A Buck/Boost/Inverting RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| MC34166D2TR4 | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 40V 3A RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| MC34166D2TR4G | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 40V 3A Buck/Boost/Inverting RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。