參數(shù)資料
型號： T1074HV
廠商： Linear Technology Corporation
英文描述： BOX EXTRUD ALUM 8.66X6.30X1.20,1
中文描述： 降壓型開關(guān)穩(wěn)壓器
文件頁數(shù)： 11/16頁
文件大小： 215K
代理商： T1074HV
LT1074/LT1076
11
Figure 8. I
LIM
Pin Circuit
Figure 9. Foldback Current Limit
DESCRIPTIO S
PI
U
I
LIM
PIN
The I
LIM
pin is used to reduce current limit below the
preset value of 6.5A. The equivalent circuit for this pin is
shown in Figure 8.
Q1
R1
8K
TO LIMIT
CIRCUIT
V
IN
320 A
D1
D3
6V
I
LIM
4.3V
D2
LT1047PD12
When I
LIM
is left open, the voltage at Q1 base clamps at 5V
through D2. Internal current limit is determined by the
current through Q1. If an external resistor is connected
between I
LIM
and ground, the voltage at Q1 base can be
reduced for lower current limit. The resistor will have a
voltage across it equal to (320
μ
A)(R), limited to
≈
5V when
clamped by D2. Resistance required for a given current
limit is:
R
LIM
= I
LIM
(2k
) + 1k
(LT1074)
R
LIM
= I
LIM
(5.5k
) + 1k
(LT1076)
As an example, a 3A current limit would require
3A(2k) + 1k = 7k
for the LT1074. The accuracy of these
formulas is
±
25% for 2A
≤
I
LIM
≤
5A (LT1074) and
7A
≤
I
LIM
≤
1.8A (LT1076), so I
LIM
should be set at least
25% above the peakswitch current required.
Foldback current limiting can be easily implemented by
adding a resistor from the output to the I
LIM
pin as shown
in Figure 9. This allows full desired current limit (with or
without R
LIM
) when the output is regulating, but reduces
current limit under short-circuit conditions. A typical value
for R
FB
is 5k
, but this may be adjusted up or down to set
the amount of foldback. D2 prevents the output voltage
from forcing current back into the I
LIM
pin. To calculate a
value for R
FB
, first calculate R
LIM
, the R
FB
:
(
(
0. *
1
R
I
R
)
R
k
I
R ink
(
FB
SC
L
SC
=
)( )
*
)
0 44
.
*Change 0.44 to 0.16, and 0.5 to 0.18 for LT1076.
Example:
I
LIM
= 4A, ISC = 1.5A, R
LIM
= (4)(2k) + 1k = 9k
(
0 5 9
1
1 5
.
.
R
k
k
k
k
FB
=
)
)
(
)
1.
3 8
.
.
Error Amplifier
The error amplifier in Figure 10 is a single stage design
with added inverters to allow the output to swing above
and below the common mode input voltage. One side of
the amplifier is tied to a trimmed internal reference voltage
of 2.21V. The other input is brought out as the FB (feed-
back) pin. This amplifier has a G
M
(voltage “in” to current
“out”) transfer function of
≈
5000
μ
mho. Voltage gain is
determined by multiplying G
M
times the total equivalent
output loading, consisting of the output resistance of Q4
and Q6 in parallel with the series RC external frequency
compensation network. At DC, the external RC is ignored,
and with a parallel output impedance for Q4 and Q6 of
400k
, voltage gain is
≈
2000. At frequencies above a few
hertz, voltage gain is determined by the external compen-
sation, R
C
and C
C
.
V
OUT
I
LIM
FB
R
LIM
R
FB
D2
1N4148
LT1074PD13
LT1074
相關(guān)PDF資料
PDF描述
T10A100 MICROMATE FEMALE PCB EDGEMT. RoHS Compliant: Yes
T10A200 RF Coaxial Connector Adapter; Body Material:Brass; Body Style:Straight Bulkhead Adapter, Jack-Jack; Impedance:50ohm; Leaded Process Compatible:Yes; Series:N; Contact Termination:Clamp/Solder; Frequency Max:11GHz RoHS Compliant: Yes
T10A BOX EXTRUD ALUM 8.66X6.30X2.03,1
T10A062 Glass passivated junction
T10A068 Glass passivated junction
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
T1075 功能描述:變壓器音頻和信號 T1/E1 XFMR DUAL BH RoHS:否 制造商:Skyworks Solutions, Inc. 頻率范圍:810 MHz to 960 MHz 初級線圈阻抗: 次級線圈阻抗: 絕緣電壓:23 dB 工作溫度范圍:- 40 C to + 85 C 端接類型:SMD/SMT 尺寸:6 mm L x 4.9 mm W x 1.6 mm H 產(chǎn)品:Splitters and Combiners
T-1075 制造商:RHOMBUS-IND 制造商全稱:Rhombus Industries Inc. 功能描述:FLYBACK TRANSFORMER
T1075-0001 制造商:Amphenol Commercial 功能描述:SFP 1X1 CAGE EXTRACTION TOOL
T1075-0002 制造商:Amphenol Commercial 功能描述:SFP 2X1 CAGE EXTRACTION TOOL
T1075-0003 制造商:Amphenol Commercial 功能描述:SFP 2X1 CONNR EXTRACTION TOOL
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