数据搜索系统,热门电子元器件搜索
  Chinese  ▼
ALLDATASHEETCN.COM

X  

LTC1142 数据表(PDF) 9 Page - Linear Technology

部件名 LTC1142
功能描述  Dual High Efficiency Synchronous Step-Down Switching Regulators
Download  20 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
制造商  LINER [Linear Technology]
网页  http://www.linear.com
标志 LINER - Linear Technology

LTC1142 数据表(HTML) 9 Page - Linear Technology

Back Button LTC1142 Datasheet HTML 5Page - Linear Technology LTC1142 Datasheet HTML 6Page - Linear Technology LTC1142 Datasheet HTML 7Page - Linear Technology LTC1142 Datasheet HTML 8Page - Linear Technology LTC1142 Datasheet HTML 9Page - Linear Technology LTC1142 Datasheet HTML 10Page - Linear Technology LTC1142 Datasheet HTML 11Page - Linear Technology LTC1142 Datasheet HTML 12Page - Linear Technology LTC1142 Datasheet HTML 13Page - Linear Technology Next Button
Zoom Inzoom in Zoom Outzoom out
 9 / 20 page
background image
9
LTC1142/LTC1142L/LTC1142HV
OPERATIO
Refer to Functional Diagram
As the load current increases, the output voltage de-
creases slightly. This causes the output of the gain stage
[Pin 27(13)] to increase the current comparator thresh-
old, thus tracking the load current.
The sequence of events for Burst Mode operation is very
similar to continuous operation with the cycle interrupted
by the voltage comparator. When the output voltage is at
or above the desired regulated value, the P-channel
MOSFET is held off by comparator V and the timing
capacitor continues to discharge below VTH1. When the
timing capacitor discharges past VTH2, voltage compara-
tor S trips, causing the internal sleep line to go low and the
N-channel MOSFET to turn off.
The circuit now enters sleep mode with both power
MOSFETs turned off. In sleep mode a majority of the
circuitry is turned off, dropping the quiescent current
from 1.6mA to 160
µA (for one regulator block). The load
current is now being supplied from the output capacitor.
When the output voltage has dropped by the amount of
hysteresis in comparator V, the P-channel MOSFET is
again turned on and this process repeats.
To avoid the operation of the current loop interfering with
Burst Mode operation, a built-in offset VOS is incorporated
in the gain stage. This prevents the current comparator
threshold from increasing until the output voltage has
dropped below a minimum threshold.
To prevent both the external MOSFETs from ever being
turned on at the same time, feedback is incorporated to
sense the state of the driver output pins. Before the NDrive
output can go high, the PDrive output must also be high.
Likewise, the PDrive output is prevented from going low
while the NDrive output is high.
Using constant off-time architecture, the operating fre-
quency is a function of the input voltage. To minimize the
frequency variation as dropout is approached, the off-time
controller increases the discharge current as VIN drops
below VOUT + 1.5V. In dropout the P-channel MOSFET is
turned on continuously (100% duty cycle) providing low
dropout operation with VOUT ~ VIN.
The basic LTC1142 application circuit is shown in Figure
1. External component selection is driven by the load
requirement and begins with the selection of RSENSE.
Once RSENSE is known, CT and L can be chosen. Next, the
power MOSFETs and D1 are selected. Finally, CIN and
COUT are selected and the loop is compensated. Since the
3.3V and 5V sections in the LTC1142 are identical and
similarly section 1 and section 2 in the LTC1142HV-ADJ/
LTC1142L-ADJ are identical, the process of component
selection is the same for both sections. The circuit shown
in Figure 1 can be configured for operation up to an input
voltage of 20V.
RSENSE Selection for Output Current
RSENSE is chosen based on the required output current.
The LTC1142 current comparators have a threshold range
which extends from a minimum of 25mV/RSENSE to a
maximum of 150mV/RSENSE. The current comparator
threshold sets the peak of the inductor ripple current,
APPLICATIO S I FOR ATIO
yielding a maximum output current IMAX equal to the peak
value less half the peak-to-peak ripple current.
For proper
Burst Mode operation, IRIPPLE(P-P) must be less than or
equal to the minimum current comparator threshold.
Since efficiency generally increases with ripple current,
the maximum allowable ripple current is assumed, i.e.,
IRIPPLE(P-P) = 25mV/RSENSE (see CT and L Selection for
Operating Frequency section). Solving for RSENSE and
allowing a margin for variations in the LTC1142 and
external component values yields:
RSENSE
MAX
=
100mV
I
A graph for Selecting RSENSE vs Maximum Output Current
is given in Figure 2.
The load current below which Burst Modeoperation com-
mences, IBURST, and the peak short-circuit current ISC(PK),


类似零件编号 - LTC1142

制造商部件名数据表功能描述
logo
Linear Technology
LTC1142 LINER-LTC1142 Datasheet
249Kb / 20P
   Dual High Efficiency Synchronous Step-Down Switching Regulators
LTC1142CG LINER-LTC1142CG Datasheet
249Kb / 20P
   Dual High Efficiency Synchronous Step-Down Switching Regulators
LTC1142HVCG LINER-LTC1142HVCG Datasheet
249Kb / 20P
   Dual High Efficiency Synchronous Step-Down Switching Regulators
LTC1142HVCG-ADJ LINER-LTC1142HVCG-ADJ Datasheet
249Kb / 20P
   Dual High Efficiency Synchronous Step-Down Switching Regulators
LTC1142HV LINER-LTC1142HV_15 Datasheet
258Kb / 20P
   Dual High Efficiency Synchronous Step-Down Switching Regulators
More results

类似说明 - LTC1142

制造商部件名数据表功能描述
logo
Linear Technology
LTC1267 LINER-LTC1267_15 Datasheet
104Kb / 1P
   Dual High Efficiency Synchronous Step-Down Switching Regulators
LTC1142 LINER-LTC1142_15 Datasheet
258Kb / 20P
   Dual High Efficiency Synchronous Step-Down Switching Regulators
LTC1142L LINER-LTC1142L_15 Datasheet
258Kb / 20P
   Dual High Efficiency Synchronous Step-Down Switching Regulators
LTC1142HV LINER-LTC1142HV_15 Datasheet
258Kb / 20P
   Dual High Efficiency Synchronous Step-Down Switching Regulators
LTC1267 LINER-LTC1267 Datasheet
341Kb / 16P
   Dual High Efficiency Synchronous Step-Down Switching Regulators
LTC1267-ADJ5 LINER-LTC1267-ADJ5_15 Datasheet
104Kb / 1P
   Dual High Efficiency Synchronous Step-Down Switching Regulators
LTC1267-ADJ LINER-LTC1267-ADJ_15 Datasheet
104Kb / 1P
   Dual High Efficiency Synchronous Step-Down Switching Regulators
LTC1142 LINER-LTC1142_00 Datasheet
249Kb / 20P
   Dual High Efficiency Synchronous Step-Down Switching Regulators
LTC1267 LINER-LTC1267_02 Datasheet
94Kb / 1P
   Dual High Efficiency Synchronous Step-Down Switching Regulators
LTC1148 LINER-LTC1148 Datasheet
384Kb / 20P
   High Efficiency Synchronous Step-Down Switching Regulators
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20


数据表 下载

Go To PDF Page


链接网址




隐私政策
ALLDATASHEETCN.COM
ALLDATASHEET是否为您带来帮助?  [ DONATE ] 

关于 Alldatasheet   |   广告服务   |   联系我们   |   隐私政策   |   链接交换   |   制造商名单
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