IRU3073CQTR【PDF 10/21 页】IC REG DL BCK/LINEAR 16-QSOP

收藏本站

您好，
买卖IC网欢迎您。
请登录
免费注册

买卖IC网

Sheet目录40

6页 7页 8页 9页 [10页]11页 12页 13页 14页

Rev. 1.0

09/17/03

IRU3073

www.irf.com

FESR = ---(14)

2p3ESR3Co

PSW(TOTAL) = 133mW

FLC = ---(13)

2p3 LO3CO

RDS(ON) = 4mV31.5 = 6mV

ISET E IO(LIM) = 8A31.5 = 12A

(50% over nominal output current)

This results to: RSET E 4.8KV

Select: RSET = 5KV

VDS

VGS

10%

90%

td(ON)

td(OFF)

Figure 9 - Switching time waveforms.

From IRF7832 data sheet we obtain:

These values are taken under a certain condition test.

For more details please refer to the IRF7832 datasheet.

By using equation (12), we can calculate the total switch-

ing losses.

Programming the Over-Current Limit

The over-current threshold can be set by connecting a

resistor (RSET) from drain of low side MOSFET to the

OCSet pin. The resistor can be calculated by using equa-

tion (2).

The RDS(ON) has a positive temperature coefficient and it

should be considered for the worse case operation.

Feedback Compensation

The IRU3073 is a voltage mode controller; the control

loop is a single voltage feedback path including error

amplifier and error comparator. To achieve fast transient

response and accurate output regulation, a compensa-

tion circuit is necessary. The goal of the compensation

network is to provide a closed loop transfer function with

the highest 0dB crossing frequency and adequate phase

margin (greater than 458).

Gain

FLC

0dB

Phase

FLC

-1808

Frequency

-40dB/decade

The output LC filter introduces a double pole, 40dB/

decade gain slope above its corner resonant frequency,

and a total phase lag of 1808 (see Figure 10). The Reso-

nant frequency of the LC filter is expressed as follows:

Figure 10 shows gain and phase of the LC filter. Since

we already have 1808 phase shift just from the output

filter, the system risks being unstable.

Figure 10 - Gain and phase of LC filter.

The IRU3073s error amplifier is a differential-input

transconductance amplifier. The output is available for

DC gain control or AC phase compensation.

The E/A can be compensated with or without the use of

local feedback. When operated without local feedback,

the transconductance properties of the E/A become evi-

dent and can be used to cancel one of the output filter

poles. This will be accomplished with a series RC circuit

from Comp pin to ground as shown in Figure 11.

Note that this method requires that the output capacitor

should have enough ESR to satisfy stability requirements.

In general, the output capacitors ESR generates a zero

typically at 5KHz to 50KHz which is essential for an

acceptable phase margin.

The ESR zero of the output capacitor expressed as fol-

lows:

IRF7832

tr = 12.3ns

tf = 21ns

发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

*型号	*数量	厂商	批号	封装

添加更多采购

采购需求

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

我的联系方式