参数资料
| 型号： | MC44605PG |
| 厂商： | ON Semiconductor |
| 文件页数： | 16/20页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR FLYBK ISO PWM 16DIP |
| 产品变化通告： | Product Obsolescence 19/Dec/2008 |
| 标准包装： | 500 |
| 系列： | GreenLine™ |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 250kHz |
| 占空比： | 80% |
| 电源电压： | 10 V ~ 15 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： | -25°C ~ 85°C |
| 封装/外壳： | 16-DIP（0.300"，7.62mm） |
| 包装： | 管件 |
| 其它名称： | MC44605PGOS |
MC44605
and:
So:
Vcs + R
S
Ipk
As in the MPL section, the squared Ipk term is estimated
by building a current source proportional to Vcs 2 .
The duty cycle is taken into account thanks to the action
on this current source of a “chopper” controlled by the
2 R Γ C R 2
V
Pin
+
P
P
MPL
R 2
(Pin) max
MPL
T
S
V + R k Vcs 2 d
MPL MPL T S
MPL L
A comparator is used to compare V MPL to V ref , the output
of which, Dis MPL , is connected to the “definitive inhibition
latch” of the disabling block. So, when the calculated power
is higher than the threshold, the circuit is definitively
disabled (the system considers that there is an overload
condition).
Finally, replacing V MPL by 2.5 V (the threshold value),
the R MPL value to be used, can be deducted:
1.25 L
R +
Γ C
Vc s
circuit output. By this means, the pin 6 average current is
proportional to the squared peak current multiplied to the
duty cycle (refer to Figure 14).
So, using an external resistor and capacitor network
(R OHD , C OHD ) on this pin, a voltage V OHD , proportional to
the conduction losses can be obtained.
Like in the MPL block, this voltage V OHD , is compared to
2.5 V. If V OHD gets higher than this threshold, the disabling
block is activated by Dis OHD (output of the comparator).
The external resistor R OHD choice enables to obtain a
calculated V OHD equal to 2.5 V when the conduction losses
are equal to their maximum value.
In effect,
OHD OHD OHD
where: k OHD is the multiplier gain
k
+ k2
ref
x
k OHD Vcs 2
k MPL Vcs 2
Now, as k OHD that is depending on the reference current
source I ref , is proportional to 1/R ref :
1
OHD R
where: k2 is a constant
Disabling
Vcs 2
R
Γ Vcs 2
ref
T OHD
Output
V MPL
Dis OHD
2.5 V
T MPL
Sf
So:
Finally:
V
V
OHD
OHD
+ R
R
+
OHD
OHD
k2 d
OHD
R
ref
d
V MPL
Block
where: Γ OHD is the OHD parameter as defined in the
specification. This is a constant equal to k2.
2.5 V
Dis MPL
Now, as:
Vcs + R
S
Ipk
MC44605
So, replacing Vcs and using the p on equation:
ref
R 2
Figure 14. OHD and MPL
V
OHD
+
3
R
OHD
R
Γ
R
OHD
dson
S
p on
Overheating Detection Section (O.H.D.)
In the MPL block, the converter input power is calculated.
In the O.H.D. block, that is the power MOSFET heating
which is calculated, using the following equation:
3
p on + 1 R dson Ipk 2 d
So, by choosing the value of R OHD , the heating
corresponding to V ref is determined. If the MOSFET
dissipation is such that the heating is higher than this
threshold, the “definitive inhibition latch” of the Disabling
Block is activated and so, the output gets definitively
disabled.
where: p on are the power switch on ? time losses
R dson is the conduction MOSFET resistor
d is the duty cycle
http://onsemi.com
16
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| MC44608P40G | 功能描述:电压模式 PWM 控制器 40KHz High Voltage SMPS PWM RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
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