参数资料
| 型号： | NCP4330DR2G |
| 厂商： | ON Semiconductor |
| 文件页数： | 9/17页 |
| 文件大小： | 0K |
| 描述： | IC DRIVER POST REGULATION 8-SOIC |
| 标准包装： | 1 |
| 输出隔离： | 非隔离 |
| 频率范围： | 达 400kHz |
| 输入电压： | 5.2 V ~ 20 V |
| 输出电压： | 0.9 V ~ 23.5 V |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOICN |
| 包装： | 剪切带 (CT) |
| 其它名称： | NCP4330DR2GOSCT |
NCP4330
DETAILED OPERATING DESCRIPTION
df +
Iramp
Voutn + dn * n s * Vin,
tRST ) tLS, HS )
don_HS + 1 *
Introduction
The NCP4330 is designed for forward, multiple output
power supplies using synchronous rectification. One output
is traditionally regulated thanks to a regulation arrangement
that modulates the forward converter duty cycle. The other
outputs are regulated by a dual MOSFET arrangement
driven by the NCP4330. The high ? side MOSFET turns on
during one part of the forward converter on ? time, while the
low ? side power switch is ON for the rest of the period (free
wheeling).
The sequencing of the switching phases, includes
over ? laps that result in only one hard switching (high ? side
turn on). The three other transitions are soft for an optimum
efficiency.
The synchronous rectification enables to keep a
Continuous Conduction Mode (CCM) operation whatever
the load is, as this technique allows to send back some
energy towards the input (light load conditions). In
Continuous Conduction Mode (CCM), the forward duty
cycle is simply given by the following equation:
Vout1
(ns np) * Vin
where: ? d f is the forward duty cycle,
? n s /n p is the transformer turn ratio (n p : primary
number of turns, n s : secondary number of turns),
? Vin is the forward converter input voltage,
? Vout1 is the main output voltage of the forward
converter.
The post ? regulated output voltages are given by the
following equation:
n
p
where d n is the duty cycle of the post ? regulator n, with
d n < d f since (n s *Vin/n p ) is available only during the
forward converter on ? time.
Post ? regulated output voltages are then necessarily lower
than the main regulated one.
Sequencing and Regulation Block
The timing diagram of page 2 portrays the phases
sequencing.
Typically, a regulation arrangement injects a current into
pin 5, in order to adjust the high ? side MOSFET duty cycle.
Pin 5 current is internally mirrored in order to charge the
C ramp capacitor. An internal comparator (1.0 V hysteresis)
detects when the capacitor voltage exceeds the 2.5 V internal
reference. At that moment, the low ? side MOSFET turns off.
100 ns later (typically), the high–side MOSFET switches on
and keeps on until (following the turn off of the forward
converter power switch) a RESET signal is applied to pin 3.
At that time, an internal switch grounds the C ramp pin and
abruptly discharges the C ramp capacitor. As a consequence,
the internal comparator turns low and forces the low ? side
MOSFET on. The high ? side MOSFET turns off 100 ns later.
During the 100 ns during which both high and low side
MOSFETs are on, the MOSFET Q1 of the application
schematic is off and no energy can then be drawn from the
converter transformer. Therefore, these 100 ns should not be
considered as a part of the high ? side MOSFET conduction
time which can be computed as follows:
ton_HS + Tsw * tRST * tLS, HS * tcharge
where: ? T sw is the forward switching period,
? t RST is the C ramp reset time during which the
capacitor is kept grounded,
? t LS,HS is the delay between the low ? side turn off
and the high ? side switch on. During this time,
100 ns typically, the two drivers are in low state,
? t charge is the time necessary to charge the C_ramp
capacitor up to the 2.5 V reference voltage.
Given that:
Cramp * Vref
tcharge +
where: ? C ramp is the capacitor connected to the C_ramp
pin,
? I ramp is the current injected into the I_ramp pin,
? Vref is the 2.5 V reference voltage,
the following equation dictates the high ? side MOSFET duty
cycle:
Cramp*Vref
Iramp
Tsw
The following curve gives d on_HS versus the current I ramp
in the following conditions: 400 kHz switching frequency,
250 ns reset pulse duration, 100 ns switching delay (between
LS and HS), 100 pF C ramp capacitor.
http://onsemi.com
9
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相关代理商/技术参数 |
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|---|---|
| NCP4331 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:Synchronous Buck Controller for High Efficiency Post Regulation |
| NCP4331DBR2G | 功能描述:IC REG CTRLR BUCK PWM 16-TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:100% 电源电压:8.2 V ~ 30 V 降压:无 升压:无 回扫:是 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:0°C ~ 70°C 封装/外壳:8-DIP（0.300"，7.62mm） 包装:管件 产品目录页面:1316 (CN2011-ZH PDF) |
| NCP4331DR2G | 功能描述:功率驱动器IC PWM CONTROLLER RoHS:否 制造商:Micrel 产品:MOSFET Gate Drivers 类型:Low Cost High or Low Side MOSFET Driver 上升时间: 下降时间: 电源电压-最大:30 V 电源电压-最小:2.75 V 电源电流: 最大功率耗散: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Tube |
| NCP433FCT2G | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:1.5A Ultra-Small Controlled Load Switch with Auto-Discharge Path |
| NCP434 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:2A Ultra-Small Controlled Load Switch with |
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