NCP1083
http://onsemi.com
16
Both VDDH and VDDL regulators turn on as soon as
VPORT reaches the Vuvlo_on threshold.
Error Amplifier
In nonisolated converter topologies, the high gain
internal error amplifier of the NCP1083 and the internal
1.2 V reference voltage regulate the DCDC output voltage.
In this configuration, the feedback loop compensation
network should be inserted between the FB and COMP pins
as shown in Figures 3, 4 and 5.
In isolated topologies the error amplifier is not used
because it is already implemented externally with the shunt
regulator on the secondary side of the DCDC controller
(see Figure 2). Therefore the FB pin must be strapped to
ARTN and the output transistor of the optocoupler has to
be connected on the COMP pin where an internal 5 kW
pullup resistor is tied to the VDDL supply (see Figure 16).
SoftStart
The softstart function provided by the NCP1083 allows
the output voltage to ramp up in a controlled fashion,
eliminating output voltage overshoot. This function is
programmed by connecting a capacitor C
SS
between the SS
and ARTN pins.
While the DCDC controller is in POR, the capacitor C
SS
is fully discharged. After coming out of POR, an internal
current source of 5 mA typically starts charging the capacitor
C
SS
to initiate softstart. When the voltage on SS pin has
reached 0.45 V (typical), the gate driver is enabled and
DCDC operation starts with a duty cycle limit which
increases with the SS pin voltage. The softstart function is
finished when the SS pin voltage goes above 1.6 V for which
the duty cycle limit reaches its maximum value of 80
percent.
Softstart can be programmed by using the following
equation:
t
SS
(ms) + 0.23 C
SS
(nF)
Current Limit Comparator
The NCP1083 current limit block behind the CS pin
senses the current flowing in the external MOSFET for
current mode control and cyclebycycle current limit. This
is performed by the current limit comparator which, on the
CS pin, senses the voltage across the external Rcs resistor
located between the source of the MOSFET and the ARTN
pin.
The NCP1083 also provides a blanking time function on
CS pin which ensures that the current limit and PWM
comparators are not prematurely trigged by the current spike
that occurs when the switching MOSFET turns on.
Slope Compensation Circuitry
To overcome subharmonic oscillations and instability
problems that exist with converters running in continuous
conduction mode (CCM) and when the duty cycle is close
or above 50 percent, the NCP1083 integrates a current slope
compensation circuit. The amplitude of the added slope
compensation is typically 110 mV over one cycle.
As an example, for an operating switching frequency of
250 kHz, the internal slope provided by the NCP1083 is
27.5 mV/ mA typically.
DCDC Controller Oscillator
The frequency is configured with the Rosc resistor
inserted between OSC and ARTN, and is defined by the
following equation:
R
OSC
(kW) +
38600
F
OSC
(kHz)
The duty cycle limit is fixed internally at 80 percent.
发布紧急采购，3分钟左右您将得到回复。
相关PDF资料
NCP1501DMR2G
IC REG SGL BUCK/LINEAR 8MICRO
NCP1578MNR2G
IC REG DL BCK/LINEAR SYNC 20-QFN
NCP1601BDR2G
IC PFC CTRL CRM/TRANSITION 8SOIC
NCP1603D100R2G
IC CTLR PFC/PWM COMBO 16-SOIC
NCP1605DR2G
IC PFC CONTROLLER CCM/DCM 16SOIC
NCP1606BDR2G
IC POWER FACTOR CONTROLLER 8SOIC
NCP1607BDR2G
IC PFC CONTROLLER CRM 8SOIC
NCP1611BDR2G
IC PFC CTLR HE ENHANCED 8-SOIC
相关代理商/技术参数
NCP1083DER2G
功能描述:DC/DC 开关控制器 POE-PD 40W DC-DC AUX SUPP RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK
NCP1083QBCGEVB
功能描述:电源管理IC开发工具 HIGH POWER POE-PD MODULE
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
NCP1083WIRGEVB
功能描述:电源管理IC开发工具 POE-PD MODULE WITH VAUX
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
NCP1086
制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:1.5 A Adjustable and 3.3 V Fixed Output Linear Regulator
NCP1086/D
制造商:未知厂家 制造商全称:未知厂家 功能描述:1.5 A Adjustable and 3.3 V Fixed Output Linear Regulator
NCP1086_05
制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:1.5 A Adjustable and 3.3 V Fixed Output Linear Regulator
NCP1086D2T-033
功能描述:低压差稳压器 - LDO 3.3V 1.5A RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20
NCP1086D2T-33
制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:1.5 A Adjustable and 3.3 V Fixed Output Linear Regulator
