參數(shù)資料
型號(hào)： LP2975IMMX-5.0
廠商： NATIONAL SEMICONDUCTOR CORP
元件分類： 模擬信號(hào)調(diào)理
英文描述： MOSFET LDO Driver/Controller
中文描述： SPECIALTY ANALOG CIRCUIT, PDSO8
封裝： MINI, SOP-8
文件頁(yè)數(shù)： 9/19頁(yè)
文件大?。?/td> 715K
代理商： LP2975IMMX-5.0
Reference Designs
(Continued)
photo below). The total overshoot increases from 50 mV to
about 75 mV, and the second “ring” on the transient is no-
ticeably larger.
The design is next tested with only a 4.7 μF output capacitor
(see scope photo below). Observe that the vertical scale has
been increased to 100 mV/division to accommodate the
250 mV undershoot. More important is the severe ringing
as the transient decays. Most designers would recognize
this immediately as the warning sign of a marginally stable
design.
The reason this design is marginally stable is that the 4.7 μF
output capacitor (along with the 6
output load) sets the pole
f
at 5 kHz. Analysis shows that the unity-gain frequency of
the loop is increased to about 100 kHz, allowing the FET’s
gate capacitance pole f
to cause significant phase shift be-
fore the loop gain goes below unity. Also, because of the low
output voltage, the feedforward capacitor provides less than
10 of positive phase shift. For good stability, the output
capcitor needs to be larger than 4.7 μF.
For detailed information on stability and phase margin, see
the Application Hints section.
DESIGN
#
3: V
= 1.5V
@
6A.
(Refer to Typical
Application Circuits, Adjustable Voltage Regulator)
COMPONENTS:
C
IN
= 1000 μF Aluminum Electrolytic
C
OUT
= 4 X 330 μF OSCON Aluminum Electrolytic
C
C
= NOT USED
R1 = 261
, 1%
R2 = 1.21 k
, 1%
R
SC
= 6 m
P-FET = NDP6020P
Heatsink: (Assuming V
≤
3.3V and T
≤
60C) if protection
against a continuousshort-circuit is required, a heatsink with
θ
<
2.5 C/W must be used. However, if continuous short-
circuit survivability is not needed, a heatsink with
θ
S-A
<
7 C/W is adequate.
PERFORMANCE DATA:
Dropout Voltage
Dropout voltage is defined as the minimum input-to-output
differential voltage required by the regulator to keep the out-
put in regulation. It is measured by reducing V
until the out-
put voltage drops below the nominal value (the nominal
value is the output voltage measured with V
IN
= 3.3V). I
L
=
6A for this test.
DROPOUT VOLTAGE = 0.68V
Load Regulation
Load regulationis defined as the maximum change in output
voltage as the load current is varied. It is measured by
changing the load resistance and recording the minimum/
maximum output voltage. The measured change in output
voltage is divided by the nominal output voltage and ex-
pressed as a percentage. V
IN
= 3.3V for this test.
0
≤
I
L
≤
6A: LOAD REGULATION = 0.092%
Line Regulation
Line regulation is defined as the maximum change in output
voltage as the input voltage is varied. It is measured by
changing the input voltage and recording the minimum/
maximum output voltage. The measured change in output
voltage is divided by the nominal output voltage and ex-
pressed as a percentage. I
L
= 6A for this test.
3.3V
≤
V
IN
≤
5V: LINE REGULATION = 0.033%
Output Noise Voltage
Output noise voltage was measured by connecting a wide-
band AC voltmeter (HP 400E) directly across the output ca-
pacitor. V
IN
= 3.3V and I
L
= 6A for this test.
NOISE = 60 μV (rms)
Transient Response
Transient response is defined as the change in output volt-
age which occurs after the load current is suddenly changed.
V
IN
= 3.3V for this test.
The load resistor is connected to the regulator output using a
switch so that the load current increases from 0 to 6A
abruptly. The change in output voltage is shown in the scope
photo (the vertical scale is 50 mV/division and the horizontal
scale is 20 μs/division. The regulator nominal output (1.5V)
is located on the center line of the photo.Amaximum change
of about 80 mV is shown.
DS100034-39
Transient Response with Output Capacitor Halved
DS100034-40
Transient Response with Only 4.7 μF Output Cap
www.national.com
9
相關(guān)PDF資料
PDF描述
LP2975AIMM-12 MOSFET LDO Driver/Controller
LP2975IMM-12 MOSFET LDO Driver/Controller
LP2975 Quadruple 2-Input Exclusive-OR Gates 14-SOIC -40 to 85
LP2978 Micropower SOT, 50 mA Low-Noise Ultra Low-Dropout Regulator
LP2978AIM5-3.8 Micropower SOT, 50 mA Low-Noise Ultra Low-Dropout Regulator
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LP2978AY-3.8 WAF 制造商:Texas Instruments 功能描述:
LP2978IM5-3.8 制造商:Rochester Electronics LLC 功能描述:50MA LDO REGULATOR, LOW-NOISE - Bulk 制造商:Texas Instruments 功能描述:
LP2978IM5X-3.8 制造商:Rochester Electronics LLC 功能描述:50MA LDO REGULATOR, LOW-NOISE - Bulk 制造商:Texas Instruments 功能描述:
LP2980-1.57BUP6 WAF 制造商:Texas Instruments 功能描述:
LP2980-3.3BUP6 WAF 制造商:Texas Instruments 功能描述:
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*