Datasheet > FAN501A

FAN501A

更新时间： 2024-02-13 06:48:55

品牌	Logo	应用领域
飞兆/仙童 - FAIRCHILD		/
页数	文件大小	规格书
16页	1348K
描述
Offline DCM / CCM Flyback PWM Controller for Charger Applications

阅读下载

中文翻译

获取价格

数据手册

如果您发现信息不准确，欢迎纠错

FAN501A 数据手册

The unified output current equation both for DCM and

CCM operation is obtained as:

t_DIS(n)

0.85∙t_DIS(n-1)

푁_푃

푡_퐷퐼푆푁_푃푉_{퐶푆_푀푖푑}푡_퐷퐼푆

200mV

(4)

퐼_푂=

∙ 퐼_{퐷푆_푀푖푑}

∙

푁

푆

푡_푆

푁

푆

푅_퐶푆

푡_푆

V_S

V_{CS_Mid}is obtained by sampling the current-sense

voltage at the middle of the MOSFET conduction time.

The diode current discharge time is obtained by

detecting the diode current zero-crossing instant. Since

the diode current cannot be sensed directly in the

primary side, Zero-Crossing Detection (ZCD) is

accomplished indirectly by monitoring the auxiliary

winding voltage in the primary side. When the diode

current reaches zero, the transformer winding voltage

begins to drop sharply. To detect the corner voltage, the

V_Sis sampled, called V_SH, at 85% of diode current

discharge time (t_DIS) of the previous switching cycle and

compared with the instantaneous V_Svoltage. When

instantaneous voltage of the VS pin drops below V_SHby

more than 200 mV, the ZCD of diode current is

obtained, as shown in Figure 23.

V_SH

ZCD

Figure 23. Operation Waveform for ZCD Function

Line Voltage Detection and its Utilization

The FAN501A indirectly senses line voltage using the

current flowing out of the VS pin while the MOSFET is

turned on, as illustrated in Figure 25 and Figure 26.

During the MOSFET turn-on period, auxiliary winding

The output current can be programmable by setting

current sensing resistor as:

voltage, V_Aux, reflects input bulk capacitor voltage, V_BLK

by the transformer coupling between primary and

auxiliary. During MOSFET conduction time, the line

voltage detector clamps the VS pin voltage ~0.5 V and

the current, I_VS, flowing from the VS pin is expressed as:

N_PV_CCR

R_CS





(5)

I_ON_SK_CC

where V_CCRis the internal voltage for CC control and

K_CCis the IC design parameter, 12 for the FAN501A.

N_A/ N_PV_BLK

0.5

I_VS



(6)

R_VS1

R_VS1/ /R_{VS 2}

I_DS-Mid

I_DS

Typically, the second term in Equation (6) can be

ignored because it is much smaller than the first term.

The current, I_VS, is approximately proportional to the line

voltage, calculated as:

½ t_ON

I_D-Mid= N_PS∙I_DS-Mid

I_O= <I_D>_Ts

I_D

N_A/ N_P

I_VS



V_BLK

(7)

½ t_DIS

R_VS1

The I_VScurrent, reflecting the line voltage information, is

used for dual switching frequency operation, CC control

correction weighting, and brownout protection; as

illustrated in Figure 25.

V_S

t_ON

t_DIS

t_S

Dual Switching Frequency

The FAN501A changes the switching frequency

between 85 kHz and 140 kHz according to the line

voltage. It is typical to design the flyback converter to

operate in CCM for low line and DCM in high line.

Therefore, the peak transformer current decreases as

the operation mode changes from CCM to DCM, as

shown in Figure 24(a), for single-frequency operation.

The transformer is not fully utilized at high line when a

single switching frequency is used. The peak

transformer current can be maintained almost constant

when the flyback converter operates at lower frequency

at high line, as illustrated in Figure 24(b). This allows full

transformer utilization and improves the efficiency by

decreasing the switching losses at high line.

Figure 21. Waveforms of DCM Flyback Converter

I_DS-Mid

I_DS

½ t_ON

I_D-Mid= N_PS∙I_DS-Mid

I_O= <I_D>_Ts

I_D

½ t_DIS

V_S

When I_VSis larger than I_VS-H(750 µA), the switching

frequency is set at f_OSC-L(85 kHz) in CV Mode. When I_VS

is less than I_VS-L(680 µA), the switching frequency is set

at f_OSC-H(140 kHz) in CV Mode. For the universal line

range, the frequency change should occur between 132

~ 180 V_ACto avoid the transition within the actual

t_ON

t_DIS

t_S

Figure 22. Waveforms of CCM Flyback Converter

www.fairchildsemi.com

FAN501A • Rev. 1.0.0

1...7 8 91011 12 13...16

中文翻译

下载PDF

与FAN501A相关器件

型号	品牌	获取价格	描述	数据表
FAN501AMPX	ONSEMI	获取价格	离线 DCM / CCM 反激 PWM 控制器，适用于充电器应用
FAN501AMPX	FAIRCHILD	获取价格	Offline DCM / CCM Flyback PWM Controller for Charger Applications
FAN5026	FAIRCHILD	获取价格	Dual DDR/Dual-output PWM Controller
FAN5026_11	FAIRCHILD	获取价格	Dual DDR / Dual-Output PWM Controller
FAN5026MTC	FAIRCHILD	获取价格	Dual DDR/Dual-output PWM Controller
FAN5026MTCX	FAIRCHILD	获取价格	Dual DDR/Dual-output PWM Controller
FAN5026MTCX	ONSEMI	获取价格	PWM 控制器，双输出/DDR
FAN5026MTCX_NL	FAIRCHILD	获取价格	Dual Switching Controller, Current-mode, 345kHz Switching Freq-Max, PDSO28, LEAD FREE, MO-
FAN5029	FAIRCHILD	获取价格	8-Bit Programmable 2- to 5-Phase Synchronous Buck Controller
FAN5029_07	FAIRCHILD	获取价格	8-Bit Programmable 2- to 5-Phase Synchronous Buck Controller

与FAN501A相关文章

LM317T数据手册解读：产品特性、应用、封装与引脚详解
2024-06-14

11
一文带你了解?DB3二极管好坏判断、参数信息、替代推荐
2024-06-14

14
LM358DR数据手册：引脚说明、电气参数及替换型号推荐
2024-06-14

8
OP07CP数据手册解读：引脚信息、电子参数
2024-06-14

12

产品中心

服务支持

精选活动

关于我们

帮助中心

FAN501A

FAN501A 数据手册

与FAN501A相关器件

与FAN501A相关文章

您还可以找

产品中心

服务支持

精选活动

关于我们

帮助中心

FAN501A

FAN501A 数据手册

与FAN501A相关器件

与FAN501A相关文章

您还可以找

您在本页遇到什么问题？