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參數資料
| 型號： | MC44604 |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | High Safety Pulsed Mode Stanby GreenLine PWM Controller |
| 中文描述： | 高安全性脈沖模式Stanby二七二三六七六七PWM控制器 |
| 文件頁數： | 18/24頁 |
| 文件大小： | 341K |
| 代理商： | MC44604 |
MC44604
http://onsemi.com
18
The overvoltage section is enabled 5
μ
s after the regulator
has started to allow the reference Vref to stabilize.
By connecting external resistors to pin 6, the threshold
VCC level can be changed.
Figure 38. VCC Management
Reference Block:
Voltage and Current
Sources Generator
(Vref, Iref, ...)
Vref enable
CSTART–UP
1
0
1
0
Vdisable
7.5 V or
12.5 V
START–UP
14.5 V
UVLO1
(to SOFTSTART)
Vdisable1
9.0 V
CUVLO1
Rref
Pin 16
MC44604
VCC
(Pin 1)
Undervoltage Lockout Section
As depicted in Figure 39, an undervoltage lockout has
been incorporated to guarantee that the IC is fully functional
before allowing operation of the system.
Indeed, the VCC is connected to the non inverting input of
a comparator that has an upper threshold equal to 14,5 V
(Vstup–th) and a lower one equal to 7.5 V (Vdisable2) in
normal mode and 14.5 V and 12.5 V in Standby mode
(typical values) (Note 1).
This hysteresis comparator enables or disables the
reference block that generates the voltage and current
sources required by the system.
This block particularly, produces Vref (pin 16 voltage)
and Iref that is determined by the resistor Rref connected
between pin 16 and the ground:
Iref
Vref
Rref
where Vref
2.5 V (typically)
In addition to this, VCC is compared to a second threshold
level that is nearly equal to 9 V (Vdisable1) so that in normal
mode, a signal UVLO1 is generated to reset the maximum
duty cycle and soft–start block and so, to disable the output
stage (refer to Max. Duty Cycle and Soft–Start §) as soon as
VCC becomes lower than Vdisable1. In this way, the circuit is
reset and made ready for a next start–up, before the reference
block is disabled (refer to Figure 26). In standby, UVLO1 is
not active (there is no need to discharge the soft–start
capacitor as the soft–start pin is maintained short circuited).
Note 1. In standby the difference between Vdisable2 and
Vstup–th is decreased not to have too low pulsed mode
frequencies.
Thus, finally in normal mode, the upper Vcc limit that
enables the output to be active, is 9.4 V (maximum value of
Vdisable1) and so the minimum hysteresis is 4.2 V.
[(Vstup–th)min = 13.6 V].
The large hysteresis and the low start–up current of the
MC44604 make it ideally suited for off–line converter
applications where efficient bootstrap start–up techniques
are required.
Standby Management
The MC44604 has been designed to detect the transitions
between the standby and normal mode and to manage each
mode in an optimal way.
In standby, the device monitors a pulsed mode that enables
to drastically reduce the power consumption.
Pulsed Mode
The MC44604 standby is preferably associated to a
flyback configuration as depicted in Figure 39.
Figure 39. Standby Flyback Configuration
MC44604
Lp
VCC
Input
Voltage
P
Vstby
Regulator
1 0
1 = Standby
0 = Normal
Mode
In effect, by this means, all the output regulation levels are
divided by the ratio:
VHV
Vstby
where VHV is the normal mode high voltage regulation
level, Vstby is the standby
μ
P supply voltage.
For instance, in the case of TV or monitors applications,
the output levels (except the
μ
P supply voltage, Vstby) are
drastically reduced by a ratio in the range of 10.
Consequently, as the output voltages are reduced, the
losses due to the output leakage consumption, are practically
eliminated, without having to disconnect the loads.
Start–up Operations
The choice of the right configuration (normal or standby)
is performed at each start–up.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| MC44604_05 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:High Safety Pulsed Mode Standby GreenLine TM PWM Controller |
| MC44604P | 功能描述:電流型 PWM 控制器 Voltage Mode PWM RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| MC44604PG | 功能描述:電流型 PWM 控制器 Voltage Mode PWM w/Bust Mode Standby RoHS:否 制造商:Texas Instruments 開關頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數量:1 最大工作溫度:+ 105 C 安裝風格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| MC44605 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:High Safety, Latched Mode, GreenLine PWM Controller for (Multi)Synchronized Applications |
| MC44605_06 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:High Safety, Latched Mode, GreenLine TM PWM Controller for (Multi) Synchronized Applications |
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