データシートサーチシステム
  Japanese  ▼
ALLDATASHEET.JP

X  

LM27953 データシート(PDF) 8 Page - National Semiconductor (TI)

[Old version datasheet] Texas Instruments acquired National semiconductor.
部品番号 LM27953
部品情報  White LED Driver with Four LED Current Sinks and 3/2x Switched Capacitor Boost
Download  11 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
メーカー  NSC [National Semiconductor (TI)]
ホームページ  http://www.national.com
Logo NSC - National Semiconductor (TI)

LM27953 データシート(HTML) 8 Page - National Semiconductor (TI)

Back Button LM27953 Datasheet HTML 3Page - National Semiconductor (TI) LM27953 Datasheet HTML 4Page - National Semiconductor (TI) LM27953 Datasheet HTML 5Page - National Semiconductor (TI) LM27953 Datasheet HTML 6Page - National Semiconductor (TI) LM27953 Datasheet HTML 7Page - National Semiconductor (TI) LM27953 Datasheet HTML 8Page - National Semiconductor (TI) LM27953 Datasheet HTML 9Page - National Semiconductor (TI) LM27953 Datasheet HTML 10Page - National Semiconductor (TI) LM27953 Datasheet HTML 11Page - National Semiconductor (TI)  
Zoom Inzoom in Zoom Outzoom out
 8 / 11 page
background image
Block Diagram
20128003
Circuit Description
OVERVIEW
The LM27953 is primarily intended for Lithium-Ion battery
driven white-LED drive applications, and is well suited to
drive white LEDs that are used for backlighting small-format
displays. The part has four matched constant-current out-
puts, each capable of driving up to 20mA (or more) through
white LEDs. The well-matched current sources ensure the
current through all the LEDs is virtually identical. This keeps
brightness of all LEDs matched to near perfection so that
they can provide a consistent backlight over the entire dis-
play.
CHARGE PUMP
The core of the LM27953 is a 1.5x/1x dual-mode charge
pump. The input of the charge pump is connected to the V
IN
pin. The recommended input voltage range of the LM27953
is 2.7V to 5.5V. The output of the charge pump is the P
OUT
pin (“Pump OUTput”). The output voltage of the charge
pump is unregulated and varies with input voltage and load
current.
The charge pump operates in the 1.5x mode when the input
voltage is below 4.75V (typ.). In this mode, the input-to-
output voltage gain of the charge pump is 1.5, and the
voltage at the output of the charge pump will be approxi-
mately 1.5x the input voltage (V(P
OUT)
≈ 1.5*V
IN ). When in
the 1.5x mode, the charge pump provides the voltage boost
that is required to drive white LEDs from a Li-Ion battery.
(White LEDs typically have a forward voltage in the range of
3.3V to 4.0V. A Li-Ion battery typically is not considered to be
fully discharged until the battery voltage falls to 3.0V (ap-
prox.) )
The charge pump operates in the 1x mode when the input
voltage is above 4.75V (typ.). In these conditions, voltage
boost is not required to drive the LEDs, so the charge pump
merely passes the input voltage to P
OUT (V(POUT)
≈ V
IN).
This reduces the input current and the power dissipation of
the LM27953 when the input voltage is high.
REGULATED CURRENT OUTPUTS
The matched current outputs are generated with a precision
current mirror that is biased off the charge pump output.
Matched currents are ensured with the use of tightly
matched internal devices and internal mismatch cancellation
circuitry.
There are four regulated common anode current outputs.
There is an ON/OFF control pin for the group (EN).
The DC current through the LEDs is programmed with an
external resistor. Changing currents on-the-fly can be
achieved with the use of digital pulse (PWM) signals.
ENABLE PIN: EN
The LM27953 has an enable pin that has active-high logic
(HIGH = ON). There is an internal pull-down resistor (300k
typ.) that is connected internally between the enable pin and
GND.
www.national.com
8


同様の部品番号 - LM27953

メーカー部品番号データシート部品情報
logo
Texas Instruments
LM2795 TI1-LM2795 Datasheet
1Mb / 21P
[Old version datasheet]   Current Regulated Switched Capacitor LED Supply with Analog and PWM Brightness Control
LM2795 TI1-LM2795 Datasheet
1Mb / 24P
[Old version datasheet]   LM2794 /LM2795 Current Regulated Switched Capacitor LED Supply with Analog and PWM Brightness Control
logo
National Semiconductor ...
LM27951 NSC-LM27951 Datasheet
605Kb / 10P
   White LED Adaptive 1.5X/1X Switched Capacitor Current Driver
logo
Texas Instruments
LM27951 TI1-LM27951 Datasheet
873Kb / 20P
[Old version datasheet]   White LED Adaptive 1.5/1 Switched-Capacitor Current Driver
logo
National Semiconductor ...
LM27951SD NSC-LM27951SD Datasheet
605Kb / 10P
   White LED Adaptive 1.5X/1X Switched Capacitor Current Driver
More results

同様の説明 - LM27953

メーカー部品番号データシート部品情報
logo
Eutech Microelectronics...
EUP2796 EUTECH-EUP2796 Datasheet
263Kb / 9P
   Dual-Display White LED Driver with 3/2X Switched Capacitor Boost
logo
National Semiconductor ...
LM2796 NSC-LM2796 Datasheet
172Kb / 8P
   Dual-Display White LED Driver with 3/2x Switched Capacitor Boost
logo
Texas Instruments
LM27961 TI1-LM27961 Datasheet
267Kb / 16P
[Old version datasheet]   Dual-Display White LED Driver with 3/2x Switched Capacitor Boost
LM2796 TI1-LM2796 Datasheet
777Kb / 14P
[Old version datasheet]   Dual-Display White LED Driver with 3/2x Switched Capacitor Boost
logo
National Semiconductor ...
LM27961 NSC-LM27961 Datasheet
711Kb / 13P
   Dual-Display White LED Driver with 3/2x Switched Capacitor Boost
logo
Texas Instruments
LM2796 TI1-LM2796_16 Datasheet
782Kb / 16P
[Old version datasheet]   LM2796 Dual-Display White LED Driver with 3/2x Switched Capacitor Boost
logo
National Semiconductor ...
LM2751 NSC-LM2751 Datasheet
8Kb / 11P
   Regulated 2X, 1.5X Switched Capacitor White LED Driver
logo
Texas Instruments
LM2751SD-B TI-LM2751SD-B Datasheet
1Mb / 19P
[Old version datasheet]   LM2751 Regulated 2X, 1.5X Switched Capacitor White LED Driver
LM2751 TI1-LM2751 Datasheet
1Mb / 19P
[Old version datasheet]   LM2751 Regulated 2X, 1.5X Switched Capacitor White LED Driver
LM27951 TI1-LM27951_16 Datasheet
873Kb / 20P
[Old version datasheet]   White LED Adaptive 1.5/1 Switched-Capacitor Current Driver
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11


データシート ダウンロード

Go To PDF Page


リンク URL




プライバシーポリシー
ALLDATASHEET.JP
ALLDATASHEETはお客様のビジネスに役立ちますか?  [ DONATE ] 

Alldatasheetは   |   広告   |   お問い合わせ   |   プライバシーポリシー   |   リンク交換   |   メーカーリスト
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