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LM2754 PDF даташит

Спецификация LM2754 изготовлена ​​​​«National Semiconductor» и имеет функцию, называемую «800mA Switched Capacitor Flash LED Driver».

Детали детали

Номер произв LM2754
Описание 800mA Switched Capacitor Flash LED Driver
Производители National Semiconductor
логотип National Semiconductor логотип 

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LM2754 Даташит, Описание, Даташиты
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September 2006
LM2754
800mA Switched Capacitor Flash LED Driver with
Time-Out Protection
General Description
The LM2754 is an integrated low noise, high current
switched capacitor DC/DC converter with four regulated cur-
rent sinks. The device is optimized for driving 1 to 4 high
power white LEDs in parallel with a maximum current of
800mA. Maximum efficiency is achieved over the input volt-
age range by actively selecting the proper gain based on the
LED forward voltage and current requirements.
Two external low power resistors set the desired current for
Torch and Flash modes. The TX pin allows the device to be
forced into Torch mode during a Flash pulse, allowing for
synchronization between the RF power amplifier pulse and
Flash/Torch modes. To protect the device and Flash LEDs,
internal Time-Out circuitry turns off the LM2754 in case of a
faulty prolonged Flash mode. Internal soft-start circuitry lim-
its the amount of inrush current during start-up.
The LM2754 is available in a small 24-pin thermally en-
hanced LLP package.
Features
n Up to 800mA Output Current
n Wide Operating Input Voltage Range: 2.8V to 5.5V
n Drives 1, 2, 3 or 4 LEDs in Parallel
n Ability to Disable One Current Sink Via the SEL Pin to
Accommodate 3-LED Flash Modules
n Time-Out Circuitry Limits Flash Duration to 1 Second
n TX Input Ensures Synchronization with RF Power
Amplifier Pulse
n Adaptive 1x, 1.5x and 2x Gains for Maximum Efficiency
n 1MHz Constant Frequency Operation
n Output Current Limit
n True Shutdown Output Disconnect
n <1µA Shutdown Current
n Internal Soft-Start Limits Inrush Current
n No Inductor Required
n Total Solution Size without LED <28mm2
n Low Profile 24-Pin LLP Package (4mm x 4mm x 0.8mm)
Applications
n Camera Flash in Mobile Phones
n Flash for Digital Cameras
n Supplies for DSP’s, Microprocessors, Memory, MP3
Players, Pagers, Other Portable Devices
Typical Application Circuit
© 2006 National Semiconductor Corporation DS202028
20202801
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LM2754 Даташит, Описание, Даташиты
Connection Diagram
LM2754
24-pin No-Pullback Leadless Leadframe Package (LLP-24)
4mm x 4mm x 0.8mm
NS Package Number SQA24A
20202802
Pin Descriptions
Pin Name
Description
23,24
22
8
12, 13, 14, 15
VINSW
VIN
VOUT
D1, D2, D3, D4*
Input Voltage Connection for Switch Array. Pins 23 and 24 are connected
internally on the die. Connect VIN and VINSW pins together.
Input Voltage Connection. Connect VIN and VINSW pins together.
Output Voltage. Connect to LED Anodes.
Regulated Current Sink Inputs. (* See SEL PIN description)
1, 2, 7, 5
3
9, 16, 17
21
C1+, C1-, C2+, C2- Flying Capacitor Connections.
GNDSW
Switch Array Ground Connection. Connect GND and GNDSW pins together.
GND
Ground Connection. Connect GND and GNDSW pins together.
EN Enable Control Pin. Logic High = Normal Operation in Torch Mode.
Logic Low = Device Shut-Down. (See Note)
20 T/F Torch/Flash Control Pin. Logic High = Flash Mode. Logic Low = Torch Mode.
Device must be enabled for Torch or Flash to operate. (See Note)
10, 11
ISET1, ISET2
Current Set Resistor Connections. Connect 1% resistors to ground to set the
desired current through the LEDs. LED current is approximated by the
equation: 800 x (1.25V ÷ R). This equation corresponds to the current through
one current sink. Total LED current is equal to the sum of currents through all
current sinks connected to the LED. The equation used for Torch (ISET1) and
Flash (ISET2) resistors are the same.
19 TX RF PA synchronization control pin. Logic High = Force Torch Mode. Logic Low
= Normal Operation. (See Applications Information section for the full
operational description) (See Note)
18 SEL D4 Control Pin. Logic Low = Normal 4-LED Operation. Logic High = Disable
D4 LED Input. Connect D4 to VOUT when not used. (See Note)
4, 6 No Connect Do not connect to any node.
Note: EN, T/F, TX, and SEL pins each have a 500kresistor connected internally to GND
Ordering Information
Order Number
LM2754SQ
LM2754SQX
Package Description
No-Pullback
LLP-24
Package Marking
UZXYTT
LM2754
Supplied as Tape and Reel
(Units)
1000
4500
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LM2754 Даташит, Описание, Даташиты
Absolute Maximum Ratings (Notes 1, 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
VIN, VOUT pins
EN, T/F, TX, SEL pins
Continuous Power Dissipation
(Note 3)
Junction Temperature
(TJ-MAX-ABS)
Storage Temperature Range
Lead Temp. (Soldering, 5 sec.)
ESD Rating (Note 4)
Human Body Model
-0.3V to 6.0V
-0.3V to (VIN + 0.3V)
w/ 6.0V max
Internally Limited
150˚C
-65˚C to 150˚C
260˚C
2kV
Operating Ratings (Notes 1, 2)
Input Voltage (VIN)
Junction Temperature Range (TJ)
Ambient Temperature Range (TA)
(Note 5)
2.8V to 5.5V
-40˚C to +125˚C
-40˚C to +85 ˚C
Thermal Information
Junction-to-Ambient Thermal Resistance,
LLP-24 Package (θJA) (Note 6)
42˚C/W
Electrical Characteristics (Notes 2, 7)
Limits in standard typeface are for TJ = 25˚C, and limits in boldface type apply over the full operating junction temperature
range (-40˚C to +125 ˚C). Unless otherwise noted, specifications apply to the LM2754 Typical Application Circuit (pg.1) with
V
(IN,
INSW)
=
3.6V,
VEN
=
1.8V,
VT/F
=
0V,
VTX
=
0V,
VSEL
=
0V,
CIN
=
C1
=
C2
=
2.2µF,
COUT
=
4.7µF.
(Note
8)
Symbol
Parameter
Conditions
Min Typ Max Units
VSETx
IDx/ISETx
VHR
VOUT
ROUT
ISETx Pin Voltage
LED Current to Set Current
Ratio (Note 11)
Current Sink Headroom
Voltage (Note 10)
Output Voltage
Output Impedance
RSETx = 20k
IDx = 50mA to 100mA
IDx = 200mA
IDx = 200mA
IDx = 50mA
1x Mode, IDx = 0mA
1.5x Mode, IDx = 0mA
2x Mode, IDx = 0mA
1x Mode
1.5x Mode
−3.5%
−7%
−11.5%
1.244
795
820
550
150
4.7
4.7
5.1
0.25
1.3
+3.5%
+7%
+11.5%
V
mA/mA
mV
V
2x Mode
1.5
IQ Quiescent Supply Current 1x Mode, IDx = 0mA
1.5x Mode, IDx = 0mA
2x Mode, IDx = 0mA
ISD Shutdown Supply Current VEN = 0V
fSW Switching Frequency
VIH Logic Input High
Input Pins: EN, T/F, TX, SEL
VIL Logic Input Low
Input Pins: EN, T/F, TX, SEL
IIH
Logic Input High Current
V(EN, T/F, TX, SEL) = 1.8V
(Note 9)
0.7 mA
3.4
6.3 8
0.1 1 µA
0.7 1 1.3 MHz
1.2 V
0.4
4 µA
IIL
Logic Input Low Current
V(EN, T/F, TX, SEL) = 0V
(Note 9)
0.5 µA
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under which operation of
the device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the
Electrical Characteristics tables.
Note 2: All voltages are with respect to the potential at the GND pin.
Note 3: Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ=150˚C (typ.) and disengages at TJ =
120˚C (typ.).
Note 4: The Human-body model is a 100 pF capacitor discharged through a 1.5kresistor into each pin.
Note 5: In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may have to be
derated. Maximum ambient temperature (TA-MAX) is dependent on the maximum operation junction temperature (TJ-MAX-OP = 125oC), the maximum power
dissipation of the device in the application (PD-MAX), and the junction-to ambient thermal resistance of the part/package in the application (θJA), as given by the
following equation: TA-MAX = TJ-MAX-OP - (θJA x PD-MAX).
Note 6: Junction-to-ambient thermal resistance (θJA) is taken from a thermal modeling result, performed under the conditions and guidelines set forth in the JEDEC
standard JESD51-7. The test board is a 4 layer FR-4 board measuring 102mm x 76mm x 1.6mm. The 2 imbedded copper layers cover roughly the same area as
the board. Thickness of copper layers are 70µm/35µm/35µm/70µm (2oz/1oz/1oz/2oz). Thermal vias are placed between the die attach pad in the 1st copper layer
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