- 您现在的位置：买卖IC网 > Sheet目录346 > NCP3418DR2 (ON Semiconductor)IC MOSFET DRIVER DUAL 12V 8-SOIC
NCP3418, NCP3418A
APPLICATIONS INFORMATION
CBST =
QGATE
Δ VBST
Theory of Operation
The NCP3418 and NCP3418A are single phase MOSFET
drivers optimized for driving two N--channel MOSFETs in
a synchronous buck converter topology. The NCP3418
features an internal diode, while the NCP3418A requires an
external BST diode for the floating top gate driver. A single
PWM input signal is all that is required to properly drive the
high--side and the low--side MOSFETs. Each driver is
capable of driving a 3.3 nF load at frequencies up to 500 kHz.
Low--Side Driver
The low--side driver is designed to drive a
ground--referenced low R DS(on) N--Channel MOSFET. The
voltage rail for the low--side driver is internally connected to
the V CC supply and PGND.
When the NCP3418 is enabled, the low--side driver ’s
output is 180 _ out of phase with the PWM input. When the
device is disabled, the low--side gate is held low.
High--Side Driver
The high--side driver is designed to drive a floating low
R DS(on) N--channel MOSFET. The bias voltage for the high
side driver is developed by a bootstrap circuit referenced to
SW. The bootstrap capacitor should be connected between
the BST and SW pins.
The bootstrap circuit comprises an internal or external
diode, D1 (in which the anode is connected to V CC ), and an
external bootstrap capacitor, C BST . When the NCP3418 is
starting up, the SW pin is at ground, so the bootstrap capacitor
will charge up to V CC through D1. When the PWM input goes
high, the high--side driver will begin to turn on the high--side
MOSFET by pulling charge out of C BST . As the high--side
MOSFET turns on, the SW pin will rise to V IN , forcing the
BST pin to V IN + V CC , which is enough gate--to--source
voltage to hold the MOSFET on. To complete the cycle, the
high--side MOSFET is switched off by pulling the gate down
to the voltage at the SW pin. When low--side MOSFET turns
on, the SW pin is held at ground. This allows the bootstrap
capacitor to charge up to V CC again.
The high--side driver’s output is in phase with the PWM input.
When the device is disabled, the high side gate is held low.
Safety Timer and Overlap Protection Circuit
The overlap protection circuit prevents both the high--side
MOSFET and the low--side MOSFET from being on at the
same time, and minimizes the associated off times. This will
reduce power losses in the switching elements. The overlap
protection circuit accomplishes this by controlling the delay
from turning off the high--side MOSFET to turning on the
low--side MOSFET.
To prevent cross conduction during the high--side
MOSFET’s turn--off and the low--side MOSFET’s turn--on,
the overlap circuit monitors the voltage at the SW pin. When
the PWM input signal goes low, DRVH will go low after a
propagation delay (t pdlDRVH ), turning the high--side
MOSFET off. However, before the low--side MOSFET can
turn on, the overlap protection circuit waits for the voltage at
the SW pin to fall below 4.0 V. Once SW falls below the 4.0 V
threshold, DRVL will go high after a propagation delay
(t pdhDRVL ), turning the low--side MOSFET on. However, if
SW does not fall below 4.0 V in 300 ns, the safety timer
circuit will override the normal control scheme and drive
DRVL high. This will help insure that if the high--side
MOSFET fails to turn off it will not produce an over--voltage
at the output.
Similarly, to prevent cross conduction during the low--side
MOSFET’s turn--off and the high--side MOSFET’s turn--on,
the overlap circuit monitors the voltage at the gate of the
low--side MOSFET through the DRVL pin. When the PWM
signal goes high, DRVL will go low after a propagation delay
(t pdlDRVL ), turning the low--side MOSFET off. However,
before the high--side MOSFET can turn on, the overlap
protection circuit waits for the voltage at DRVL to drop below
1.5 V. Once this has occurred, DRVH will go high after a
propagation delay (t pdhDRVH ), turning the high--side
MOSFET on.
Application Information
Supply Capacitor Selection
For the supply input (V CC ) of the NCP3418, a local bypass
capacitor is recommended to reduce noise and supply peak
currents during operation. Use a 1.0 to 4.7 m F, low ESR
capacitor. Multilayer ceramic chip (MLCC) capacitors
provide the best combination of low ESR and small size.
Keep the ceramic capacitor as close as possible to the V CC
and PGND pins.
Bootstrap Circuit
The bootstrap circuit uses a charge storage capacitor
(C BST ) and the internal (or an external) diode. Selection of
these components can be done after the high--side MOSFET
has been chosen.
The bootstrap capacitor must have a voltage rating that is
able to withstand twice the maximum supply voltage. A
minimum 50 V rating is recommended. The capacitance is
determined using the following equation:
(eq. 1)
where Q GATE is the total gate charge of the high--side
MOSFET, and Δ V BST is the voltage droop allowed on the
high--side MOSFET drive. For example, a NTD60N03 has
a total gate charge of about 30 nC. For an allowed droop of
300 mV, the required bootstrap capacitance is 100 nF. A
good quality ceramic capacitor should be used.
If an external Schottky diode will be used for bootstrap,
it must be rated to withstand the maximum supply voltage
plus any peak ringing voltages that may be present on SW.
The average forward current can be estimated by:
IF(AVG) = QGATE × fMAX (eq. 2)
where f MAX is the maximum switching frequency of the
controller. The peak surge current rating should be checked
in--circuit, since this is dependent on the source impedance
of the 12 V supply and the ESR of C BST.
http://onsemi.com
7
发布紧急采购，3分钟左右您将得到回复。
相关PDF资料
NCP3420DR2G
IC MOSFET DRIVER DUAL 12V 8-SOIC
NCP3488DR2G
IC MOSFET DRVR DUAL 12V 8-SOIC
NCP5007SNT1
IC LED DRIVR WHT COMPACT 5TSOP
NCP5008DMR2
IC LED DRVR WHT BCKLT 10MICROSMD
NCP5010FCT1G
IC LED DRVR WHT BCKLT 8-FLIPCHIP
NCP5021MUTXG
IC WHITE LED DVR HV AMB 16-UQFN
NCP5050MTTXG
IC LED DRIVR PHOTO FLASH 10-WDFN
NCP5111DR2G
IC DRIVER HI/LOW SIDE HV 8-SOIC
相关代理商/技术参数
NCP3418DR2G
功能描述:功率驱动器IC ANA 12V MOSFET DR 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
NCP3418PDR2
制造商:Rochester Electronics LLC 功能描述:- Bulk
NCP341MUTBG
制造商:ON Semiconductor 功能描述:Controlled Load Switch Soft-Start
NCP3420DR2G
功能描述:功率驱动器IC TSMC 12V FET DRVR 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
NCP3420DR2G-CUT TAPE
制造商:ON 功能描述:NCP Series 1.8 Ohm 13.2 V Surface Mount MOSFET Driver with Dual Outputs - SOIC-8
NCP3420MNR2G
功能描述:功率驱动器IC TSMC 12V FET DRVR 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
NCP345EVB
功能描述:电源管理IC开发工具 ANA NCP345 EVAL BD
RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V
NCP345SNT1
功能描述:监控电路 6.85V OVP Supervisor RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel