参数资料
| 型号： | NCV887300D1R2G |
| 厂商： | ON Semiconductor |
| 文件页数： | 8/11页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST PWM CM 8-SOIC |
| 标准包装： | 1 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1.1MHz |
| 占空比： | 89% |
| 电源电压： | 3.2 V ~ 40 V |
| 降压： | 无 |
| 升压： | 是 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 150°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 标准包装 |
| 其它名称： | NCV887300D1R2GOSDKR |
NCV8873
THEORY OF OPERATION
V g
L
D1
Oscillator
V O
PWM
S
R
Q
Gate
Driver
GDRV
I SNS
Q
D2
C O
Comparator
Slope
Compensation
CSA
V FB
R SNS
Dn
Gm
R F1
V REF
NCV8873
Compensation
Figure 10. Current Mode Control Schematic
Current Mode Control
The NCV8873 incorporates a current mode control
scheme, in which the PWM ramp signal is derived from the
power switch current. This ramp signal is compared to the
output of the error amplifier to control the on ? time of the
power switch. The oscillator is used as a fixed ? frequency
clock to ensure a constant operational frequency. The
resulting control scheme features several advantages over
conventional voltage mode control. First, derived directly
from the inductor, the ramp signal responds immediately to
line voltage changes. This eliminates the delay caused by the
output filter and error amplifier, which is commonly found
in voltage mode controllers. The second benefit comes from
inherent pulse ? by ? pulse current limiting by merely
clamping the peak switching current. Finally, since current
mode commands an output current rather than voltage, the
filter offers only a single pole to the feedback loop. This
allows for a simpler compensation.
The NCV8873 also includes a slope compensation
scheme in which a fixed ramp generated by the oscillator is
added to the current ramp. A proper slope rate is provided to
improve circuit stability without sacrificing the advantages
of current mode control.
Current Limit
The NCV8873 features a peak current ? mode current limit
protection. When the current sense amplifier detects a
voltage above the peak current limit between ISNS and
GND after the current limit leading edge blanking time, the
peak current limit causes the power switch to turn off for the
remainder of the cycle. Set the current limit with a resistor
from ISNS to GND, with R = V CL / I limit .
If the voltage across the current sense resistor exceeds the
over current threshold voltage the part enters over current
hiccup mode. The part will remain off for the hiccup time
and then go through the soft ? start procedure.
EN/SYNC
This pin has three modes. When a dc logic high
(CMOS/TTL compatible) voltage is applied to this pin the
NCV8873 operates at the programmed frequency. When a
dc logic low voltage is applied to this pin the NCV8873
enters a low quiescent current sleep mode. When a square
wave of at least %f sync,min of the free running switching
frequency is applied to this pin, the switcher operates at the
same frequency as the square wave. If the signal is slower
than this, it will be interpreted as enabling and disabling the
part. The falling edge of the square wave corresponds to the
start of the switching cycle. If an Enable command is
received during normal operation, the minimum duration of
the Enable low ? state must be greater than 7 clock cycles.
UVLO
Input Undervoltage Lockout (UVLO) is provided to
ensure that unexpected behavior does not occur when VIN
is too low to support the internal rails and power the
controller. The IC will start up when enabled and VIN
surpasses the UVLO threshold plus the UVLO hysteresis
and will shut down when VIN drops below the UVLO
threshold or the part is disabled.
Internal Soft ? Start
To insure moderate inrush current and reduce output
overshoot, the NCV8873 features a soft start which charges a
capacitor with a fixed current to ramp up the reference voltage.
This fixed current is based on the switching frequency, so that
if the NCV8873 is synchronized to twice the default switching
frequency the soft start will last half as long.
http://onsemi.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| NCV8873LEDBSTGEVB | 制造商:ON Semiconductor 功能描述:NCV8873 EVAL BD - Bulk 制造商:ON Semiconductor 功能描述:BOARD EVAL FOR NCV8873LEDBST |
| NCV8876 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:Automotive Grade Start-Stop Non-Synchronous Boost Controller |
| NCV887600D1R2G | 制造商:ON Semiconductor 功能描述:AUTOMOTIVE GRADE NON-SYNC - Tape and Reel 制造商:ON Semiconductor 功能描述:IC REG CTRLR BST PWM CM 制造商:ON Semiconductor 功能描述:REEL / CREATING NEW OPN NCV88760 |
| NCV887601BSTGEVB | 制造商:ON Semiconductor 功能描述:NCV887601 EVAL BD - Bulk |
| NCV887601D1R2G | 制造商:ON Semiconductor 功能描述:AUTOMOTIVE GRADE NON-SYNC - Tape and Reel 制造商:ON Semiconductor 功能描述:AUTOMOTIVE GRADE NON-SYNC - Cut TR (SOS) 制造商:ON Semiconductor 功能描述:IC REG CTRLR BST PWM CM 制造商:ON Semiconductor 功能描述:REEL / AUTOMOTIVE GRADE NON-SYNC |
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