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參數資料
| 型號： | NCP1562A |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | High Performance Active Active Clamp/Reset PWM Controller Controller(高性能有效Clamp/Reset PWM控制器) |
| 中文描述： | 高性能主動有源鉗位/復位PWM控制器控制器（高性能有效鉗位/復位的PWM控制器） |
| 文件頁數： | 22/26頁 |
| 文件大小： | 277K |
| 代理商： | NCP1562A |
NCP1562A, NCP1562B
http://onsemi.com
22
The SYNC pin is in a high impedance mode during the
charging of the RTCT Ramp. In this period the oscillator
accepts an external SYNC pulse. If no pulse is detected
upon reaching the peak of the RTCT Ramp, a 100 ns SYNC
pulse is generated. The SYNC pulse is generated by
internally pulling the SYNC pin to V
REF
. The peak voltage
of the SYNC pin is typically 4.3 V. Once the 100 ns timer
expires, the pin goes back into a high impedance mode and
an external resistor is required for pulldown as shown in
Figure 49.
V
REF
RTCT
SYNC
R
SYNC
C
T
R
T
Figure 49. SYNC Pulse
The slew rate of the sync pin is determined by the pin
capacitance and external pulldown resistor. The maximum
source current of the SYNC pin is 1.0 mA. The resistor is
sized to allow the SYNC pin to discharge before the start
of the next cycle.
If an external pulse is received on the SYNC pin before
the internal pulse is generated, the controller enters the
slave mode of operation. Once operation in slave mode
commences, C
T
begins discharging and the R
T
C
T
Ramp
upper threshold is increased to 4.0 V.
If a controller in slave mode does not receive a sync pulse
before reaching the R
T
C
T
Ramp peak voltage (4.0 V), the
upper threshold is reset back to 3.0 V and the converter
reverts to operation in master mode. To guarantee the
converter stays in slave mode, the minimum clock period
of the master controller has to be less than the R
T
C
T
charge
time from 2.0 V to 4.0 V.
Two NCP1562's are synchronized by connecting their
SYNC pins together. The first device that generates a sync
pulse during powerup becomes the master. A diode
connected as shown in Figure 50 can be used to
permanently set one controller as the master. The diode
prevents the master from receiving the SYNC pulse of the
slave controller.
MASTER
CONTROLLER
SLAVE
CONTROLLER
SYNC
R
SYNC1
R
SYNC2
SYNC
Figure 50. Master-Slave Configuration
5.0 V Reference
The NCP1562 has a precision 5.0 V reference output. It
is a buffered version of the internal reference. The 5.0 V
reference is biased directly from V
AUX
and it can supply up
to 5.0 mA. Load regulation is 50 mV and line regulation is
100 mV within the specified operating range.
It is required to bypass the reference with a capacitor.
The capacitor is used for compensation of the internal
regulator and high frequency noise filtering. The capacitor
should be placed across the V
REF
and GND pins. In most
applications a 0.1 F will suffice. A bigger capacitor may
be required to reduce the voltage ripple caused by the
oscillator current. The recommended capacitor range is
between 0.047 F and 1.0 F.
During powerup, the 5.0 V reference is enabled once
V
AUX
reaches V
AUX(on)
and a UV fault is not present.
Otherwise, the reference is enabled once the UV fault is
removed and V
AUX
reaches V
AUX(on)
.
Once a UV fault is detected after the reference has been
enabled, the reference is disabled after the soft-stop
sequence is complete if the UV fault is still present. If the
UV fault is removed before soft-stop is complete, the
reference is not disabled.
Application Information
ON Semiconductor provides an electronic design tool, a
demonstration board and an application note to facilitate
design of the NCP1562 and reduce development cycle
time. All the tools can be downloaded or ordered at
www.onsemi.com.
The electronic design tool allows the user to easily
determine most of the system parameters of an active
clamp forward converter. The tool evaluates the power and
active clamp stages as well as the frequency response of the
system. The tool is used to design a converter for a 48 V
telecom system. The converter delivers 100 W at 3.3 V.
The circuit schematic is shown in Figure 51. The converter
design is described in Application Note AND8273/D.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| NCP1562A WAF | 制造商:ON Semiconductor 功能描述: |
| NCP1562ADBR2G | 功能描述:電壓模式 PWM 控制器 HI PERF RESET PWM CONTLR RoHS:否 制造商:Texas Instruments 輸出端數量:1 拓撲結構:Buck 輸出電壓:34 V 輸出電流: 開關頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| NCP1562ADR2G | 功能描述:電壓模式 PWM 控制器 HI PERF RESET PWM CONTLR RoHS:否 制造商:Texas Instruments 輸出端數量:1 拓撲結構:Buck 輸出電壓:34 V 輸出電流: 開關頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| NCP1562BDBR2G | 功能描述:電壓模式 PWM 控制器 HI PERF RESET PWM CONTLR RoHS:否 制造商:Texas Instruments 輸出端數量:1 拓撲結構:Buck 輸出電壓:34 V 輸出電流: 開關頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| NCP1562BDR2G | 功能描述:電壓模式 PWM 控制器 HI PERF RESET PWM CONTLR RoHS:否 制造商:Texas Instruments 輸出端數量:1 拓撲結構:Buck 輸出電壓:34 V 輸出電流: 開關頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
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