поискавой системы для электроныых деталей
  Russian  ▼
ALLDATASHEETRU.COM

X  

LM3100MHX датащи(PDF) 10 Page - National Semiconductor (TI)

[Old version datasheet] Texas Instruments acquired National semiconductor.
номер детали LM3100MHX
подробное описание детали  SIMPLE SWITCHER짰 Synchronous 1MHz 1.5A Step-Down Voltage Regulator
Download  15 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
производитель  NSC [National Semiconductor (TI)]
домашняя страница  http://www.national.com
Logo NSC - National Semiconductor (TI)

LM3100MHX датащи(HTML) 10 Page - National Semiconductor (TI)

Back Button LM3100MHX Datasheet HTML 6Page - National Semiconductor (TI) LM3100MHX Datasheet HTML 7Page - National Semiconductor (TI) LM3100MHX Datasheet HTML 8Page - National Semiconductor (TI) LM3100MHX Datasheet HTML 9Page - National Semiconductor (TI) LM3100MHX Datasheet HTML 10Page - National Semiconductor (TI) LM3100MHX Datasheet HTML 11Page - National Semiconductor (TI) LM3100MHX Datasheet HTML 12Page - National Semiconductor (TI) LM3100MHX Datasheet HTML 13Page - National Semiconductor (TI) LM3100MHX Datasheet HTML 14Page - National Semiconductor (TI) Next Button
Zoom Inzoom in Zoom Outzoom out
 10 / 15 page
background image
Functional Description
The LM3100 Step Down Switching Regulator features all
functions needed to implement a cost effective, efficient buck
power converter capable of supplying 1.5A to a load. This
voltage regulator contains Dual 40V N-Channel buck syn-
chronous switches and is available in a thermally enhanced
eTSSOP-20 package. The Constant ON-Time (COT) regu-
lation scheme requires no loop compensation, results in fast
load transient response, and simplifies circuit implementa-
tion. It will work correctly even with an all ceramic output
capacitor network and does not rely on the output capacitor’s
ESR for stability. The operating frequency remains constant
with line and load variations due to the inverse relationship
between the input voltage and the on-time. The valley cur-
rent limit detection circuit, internally set at 1.9A, inhibits the
high-side switch until the inductor current level subsides.
Please refer to the functional block diagram with a typical
application circuit.
The LM3100 can be applied in numerous applications and
can operate efficiently from inputs as high as 36V. Protection
features include: Thermal shutdown, V
CC
under-voltage
lockout, gate drive under-voltage lockout.
Hysteretic Control Circuit
Overview
The LM3100 buck DC-DC regulator employs a control
scheme in which the high-side switch on-time varies in-
versely with the line voltage (V
IN). Control is based on a
comparator and the one-shot on-timer, with the output volt-
age feedback (FB) compared with an internal reference of
0.8V. If the FB level is below the reference the buck switch is
turned on for a fixed time determined by the input voltage
and a programming resistor (R
ON). Following the on-time,
the switch remains off for a minimum of 260ns. If FB is below
the reference at that time the switch turns on again for
another on-time period. The switching will continue until
regulation is achieved.
The regulator will operate in discontinuous conduction mode
at light load currents, and continuous conduction mode with
heavy load current. In discontinuous conduction mode
(DCM), current through the output inductor starts at zero and
ramps up to a peak during the on-time, then ramps back to
zero before the end of the off-time. The next on-time period
starts when the voltage at FB falls below the internal refer-
ence. Until then the inductor current remains zero and the
load is supplied entirely by the output capacitor. In this mode
the operating frequency is lower than in continuous conduc-
tion mode, and varies with load current. Conversion effi-
ciency is maintained since the switching losses are reduced
with the reduction in load and switching frequency. The
discontinuous operating frequency can be calculated ap-
proximately as follows:
(1)
where R
L = the load resistance
In continuous conduction mode (CCM), current always flows
through the inductor and never reaches zero during the
off-time. In this mode, the operating frequency remains rela-
tively constant with load and line variations. The CCM oper-
ating frequency can be calculated approximately as follows:
(2)
The output voltage is set by two external resistors (R
FB1,
R
FB2). The regulated output voltage is calculated as follows:
V
OUT =0.8Vx(RFB1 +RFB2)/RFB2
(3)
Start-up Regulator (V
CC)
The start-up regulator is integrated within LM3100. The input
pin (VIN) can be connected directly to line voltage up to 36V,
with transient capability to 40V. The V
CC output regulates at
6V, and is current limited to 65 mA. Upon power up, the
regulator sources current into the external capacitor at V
CC
(C
VCC). CVCC must be at least 680nF for stability. When the
voltage on the VCC pin reaches the under-voltage lockout
threshold of 3.75V, the buck switch is enabled and the
Soft-start pin is released to allow the soft-start capacitor
(C
SS) to charge.
The minimum input voltage is determined by the dropout
voltage of V
CC, and the VCC UVLO falling threshold (
)3.7
V). If VIN is less than )4.0V, the V
CC UVLO activates to shut
off the output.
Regulation Comparator
The feedback voltage at FB is compared to the internal
reference voltage of 0.8V. In normal operation (the output
voltage is regulated), an on-time period is initiated when the
voltage at FB falls below 0.8V. The buck switch stays on for
the on-time, causing the FB voltage to rise above 0.8V. After
the on-time period, the buck switch stays off until the FB
voltage falls below 0.8V. Bias current at the FB pin is nomi-
nally 100 nA.
Over-Voltage Comparator
The voltage at FB is compared to an internal 0.92V refer-
ence. If the voltage at FB rises above 0.92V the on-time
pulse is immediately terminated. This condition can occur if
the input voltage, or the output load, changes suddenly.
Once the OVP is activated, the buck switch remains off until
the voltage at FB pin falls below 0.92V. The low side switch
will stay on to discharge the inductor energy and until the
inductor current decays to zero. The low side switch will be
turned off.
ON-Time Timer, Shutdown
The LM3100 main switch is determined by the R
ON resistor
and the input voltage (V
IN), and is calculated from:
(4)
The inverse relationship with VIN results in a nearly constant
frequency as V
IN is varied. RON should be selected for a
minimum on-time (at maximum V
IN) greater than 200 ns for
proper current limit operation. This requirement limits the
maximum frequency for each application, depending on V
IN
and V
OUT, calculated from the following:
www.national.com
10


Аналогичный номер детали - LM3100MHX

производительномер деталидатащиподробное описание детали
logo
National Semiconductor ...
LM3100MHX NSC-LM3100MHX Datasheet
3Mb / 18P
   SIMPLE SWITCHER짰 Synchronous 1MHz 1.5A Step-Down Voltage Regulator
logo
Texas Instruments
LM3100MHX TI1-LM3100MHX Datasheet
2Mb / 21P
[Old version datasheet]   SIMPLE SWITCHER짰 Synchronous 1MHz 1.5A Step-Down Voltage Regulator
LM3100MHX/NOPB TI1-LM3100MHX/NOPB Datasheet
2Mb / 21P
[Old version datasheet]   SIMPLE SWITCHER짰 Synchronous 1MHz 1.5A Step-Down Voltage Regulator
More results

Аналогичное описание - LM3100MHX

производительномер деталидатащиподробное описание детали
logo
National Semiconductor ...
LM3100 NSC-LM3100_07 Datasheet
3Mb / 18P
   SIMPLE SWITCHER짰 Synchronous 1MHz 1.5A Step-Down Voltage Regulator
logo
Texas Instruments
LM3100 TI1-LM3100_14 Datasheet
2Mb / 21P
[Old version datasheet]   SIMPLE SWITCHER짰 Synchronous 1MHz 1.5A Step-Down Voltage Regulator
LM3103 TI1-LM3103_14 Datasheet
1Mb / 20P
[Old version datasheet]   SIMPLE SWITCHER짰 Synchronous 1MHz 0.75A Step-Down Voltage Regulator
logo
National Semiconductor ...
LM3102 NSC-LM3102 Datasheet
379Kb / 18P
   SIMPLE SWITCHER짰 Synchronous 1MHz 2.5A Step-Down Voltage Regulator
LM3103 NSC-LM3103 Datasheet
351Kb / 16P
   SIMPLE SWITCHER짰 Synchronous 1MHz 0.75A Step-Down Voltage Regulator
logo
Texas Instruments
LM25575 TI1-LM25575_14 Datasheet
989Kb / 29P
[Old version datasheet]   SIMPLE SWITCHER짰 42V, 1.5A Step-Down Switching Regulator
LM5575 TI1-LM5575_14 Datasheet
993Kb / 28P
[Old version datasheet]   SIMPLE SWITCHER짰 75V, 1.5A Step-Down Switching Regulator
LM3102 TI1-LM3102_14 Datasheet
1Mb / 24P
[Old version datasheet]   SIMPLE SWITCHER Synchronous 1MHz 2.5A Step-Down Voltage Regulator
LM3103 TI1-LM3103 Datasheet
1Mb / 20P
[Old version datasheet]   SIMPLE SWITCHER Synchronous 1MHz 0.75A Step-Down Voltage Regulator
logo
National Semiconductor ...
LM1575 NSC-LM1575_07 Datasheet
848Kb / 28P
   SIMPLE SWITCHER짰 1A Step-Down Voltage Regulator
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15


датащи скачать

Go To PDF Page


ссылки URL




Конфиденциальность
ALLDATASHEETRU.COM
Вашему бизинису помогли Аллдатащит?  [ DONATE ] 

Что такое Аллдатащит   |   реклама   |   контакт   |   Конфиденциальность   |   обмен ссыками   |   поиск по производителю
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com