- 您现在的位置：买卖IC网 > Sheet目录1236 > PI2211-EVAL1 (Vicor Corporation)BOARD EVAL FOR PI2211
? ? ??
the difference between the max junction and the max
ambient temperatures is ΔT USER .
The additional terms for temperature rise and case-to-
ambient ratios will scale the RSOAS resistor value, allowing
for the fine tuning of the PI2211 digital model to the MOSFET.
For example, if the steady-state Rθ C-A of the MOSFET is less
than the default 60°C/W of the model, the value of R SOAS
would be scaled down by this ratio. This would make the
value of the sense resistor appear to be larger to the PI2211.
For a given voltage drop across the sense resistor, a larger
sense resistor value would mean less apparent current
flowing through it and therefore the calculated power across
the MOSFET is less. By scaling the apparent power a wide
range of MOSFETs can be accurately emulated by the digital
thermal model.
Similarly, if the user has a lower ΔT than the default, the net
result is that the value of the sense resistor appears to be
lower, therefore the current flowing through it appears to be
greater to the SOA model and it will calculate more power
across the MOSFET.
The scaled value of current used to determine R SOAS is used to
calculate the power across the MOSFET when calculating Tau P
and in determining the value of R SOAT .
R SOAT , R SOAR
The PI2211 thermal model has a default case-to-ambient
thermal impedance of 60°C/W, and a Tau of 2 seconds. The
junction-to-case thermal impedance and Tau P are
programmed by the R SOAT and R SOAR resistors. These can have
a maximum value of 20.0k and a minimum value of 1.30k.
?
PI2211
??
R SOAR programs the PI2211 with the junction-to-case (R θJ -C )
thermal impedance of the selected MOSFET. The ratio of the
internal R θ C-A (60°C/W) and the user's R θ C-A is used to scale
the MOSFET R θ J-C in order to maintain the correct R θ J-C to R θ C-
A ratio.
Where; 0.38 °C/(W?k) is the SOAR to R θ J-C scaling factor,
the default case-to-ambient, Rθ CA-DEFAULT , is 60°C/W,
Rθ JA-USER is the steady-state junction-to-ambient value
of the MOSFET, taken from the manufacturer's
datasheet,
Rθ JC-USER is the maximum junction-to-case value of the
MOSFET, taken from the manufacturer's datasheet.
R SOAT programs the PI2211 with the Tau P (time constant) of
the MOSFET R θJ -C and its value can be calculated after first
determining the pulse width that will cause a 60°C
temperature rise of the MOSFET junction. This can typically
be done using R θJ -C transient thermal impedance curves
provided by the FET manufacturer.
The power used for determining the pulse width is the
product of the BUS voltage and the start-up current.
Multiplying this power by R θJ -C results in a temperature rise.
Setting the maximum temperature rise to 60°C for the same
power means that the R θJ -C will have to be scaled down. Using
this scaling factor and the R θJ -C thermal impedance curves for
a single pulse, the pulse width can determined. An example
of normalized R θJ -C thermal impedance curves is shown in
Figure 16 - Determining the pulse width.
Picor Corporation · picorpower.com
PI2211
Rev 1.0, Page 20 of 26
发布紧急采购，3分钟左右您将得到回复。
相关PDF资料
PI5101-EVAL1
EVALUATION BOARD FOR PI5101
PICOSMDC035S-2
POLYSWITCH PTC RESET .35A 0805
PIIPM25P12B008X
IC PWR MODULE PROG ISO 25A 1200V
PK3020KB
KIT KEYPAD, MOUSE, AND USB HUB
PK3021LI
KIT LIGHT, MOUSE, AND USB HUB
PK3022ET
KIT CAT5 CABLE MOUSE USB HUB
PKSERIAL-I2C1
BOARD DEMO PICKIT SERIAL I2C
PKSERIAL-SPI1
BOARD DEMO PICKIT SERIAL SPI
相关代理商/技术参数
PI223MC-A6
制造商:AMI 制造商全称:AMI 功能描述:200DPI CIS Sensor
PI224MC-A6
制造商:AMI 制造商全称:AMI 功能描述:200DPI CIS Sensor
PI22-5,08
功能描述:可插拔接线端子 PCB Hdr, 45 Deg, 5,08 PitchOpen End, 22pole, 12A,300V,Grn RoHS:否 制造商:Phoenix Contact 产品:Plugs 系列:PTS 端接类型:Spring Cage 位置/触点数量:5 线规量程:26-14 节距:5 mm 电流额定值:10 A 电压额定值:250 V 安装风格: 安装角: 触点电镀:
PI225MC-A6
制造商:AMI 制造商全称:AMI 功能描述:200DPI CIS Sensor
PI226M-A4
制造商:AMI 制造商全称:AMI 功能描述:200DPI CIS Sensor
PI227
制造商:AMI 制造商全称:AMI 功能描述:200DPI CIS Sensor
PI227MC-A4
制造商:AMI 制造商全称:AMI 功能描述:200DPI CIS Sensor
PI228MC-A4
制造商:AMI 制造商全称:AMI 功能描述:200DPI CIS Sensor