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MIC5319-2.8YML-TR

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
LT1942
1
1942fb
The LT
®
1942 is a highly integrated quad switching regu-
lator designed to provide all necessary power supply
functions for TFT displays, including the white LED
backlight driver. The TFT supply incorporates two boost
and one inverting DC/DC converters. The TFT supply
output voltages are independently set, unlike charge
pump solutions which have many limitations. Power
sequencing for the TFT supply is built into the part and is
user programmable.
The LED driver is a boost DC/DC converter that can be
independently controlled. The LED driver has built-in
dimming control for precise control of LED current. An 8:1
dimming range is achieved by adjusting the CTRL4 volt-
age. The user can elect to drive a single string or two
strings of LEDs. An LED ballast circuit is included to
precisely match the LED currents if two strings of LEDs are
used. Soft-start is built into the LED driver as well as the
primary TFT supply.
The LT1942 is available in a low profile (0.75mm) 24-lead
QFN (4mm × 4mm) package.
■
Triple Output TFT Supply with Built-In
Power Sequencing
■
Integrated White LED Backlight Driver
■
Integrated Schottky Diodes
■
Active Ballast Circuitry Ensures Precise Current
Matching in White LEDs
■
Low Noise 1MHz Fixed Frequency Operation
■
2.6V to 16V Input Voltage Range
■
Soft-Start Limits Inrush Current
■
TFT Supply Output Voltages Independently Set
(Not Charge Pump Derived)
■
Power Good and Output Disconnect for TFT Supply
■
Built-In LED Dimming Capability
■
Open LED Protection for LED Driver
■
24-Lead QFN Package (4mm × 4mm)
Quad DC/DC Converter
for Triple Output TFT Supply
Plus LED Driver
■
Poly-Silicon TFT Displays
■
Amorphous Silicon TFT Displays
CTRL4
SGND/
AGND
D3 SW3
LT1942
SW1
FB1
PGND14
PGOOD
SW4
D4
LED1
LED2
FB4
FB3
PGND23
V
OUT3
NFB2
D2
SW2
0.1µF
0.22µF
47µH
V
IN
47µH
SHDN
V
CC
SS1 SS4 CT
22µH
22µH
CMDSH-3
Si2301BDS
33µH
301k
1M
100k
V
IN
4.7pF
0.1µF0.1µF
0.1µF
1942 TA01
0.22µF
2.2µF
SHUTDOWN
LED CONTROL
AV
DD
5V
40mA
4.7µF
4.7µF
698k
100k
10k
V
IN
3V TO 4.2V
V
ON
10V
2mA
V
OFF
–10V
2mA
665k
4.99Ω
20mA 20mA
TFT Bias and White LED Backlight Power Supply
APPLICATIO S
U
DESCRIPTIO
U
FEATURES
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
U
LT1942
2
1942fb
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
V
CC
Voltage............................................................. 16V
SW1, SW2, SW3 Voltage .......................... –0.4V to 36V
SW4.......................................................... –0.4V to 45V
FB1, FB3 Voltage ................................................... 2.5V
FB4 Voltage ....................................................... 400mV
NFB2 Voltage ................................................... –200mV
SHDN Voltage ......................................................... 10V
CTRL4 Voltage ........................................................ 16V
SS1, SS4 Voltage .................................................. 1.5V
Current Into D2 ......................................................... 1A
D2 Voltage ............................................................ –36V
Current Out of D3 ..................................................... 1A
D3 Voltage .............................................................. 36V
Current Out of D4 ..................................................... 4A
D4 Voltage .............................................................. 45V
LED1, LED2 Voltage ............................................... 45V
Current Into LED1, LED2 ..................................... 35mA
PGOOD Voltage ...................................................... 16V
V
OUT3
Voltage ......................................................... 36V
CT Current ........................................................... ±1mA
Maximum Junction Temperature ......................... 125°C
Operating Temperature Range (Note 2) .. – 40°C to 85°C
Storage Temperature Range ................ –65°C to 125°C
ORDER PART
NUMBER
(Note 1)
ABSOLUTE AXI U RATI GS
WWWU
PACKAGE/ORDER I FOR ATIO
UU
W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
LT1942EUF
T
JMAX
= 125°C, θ
JA
= 37°C/W, θ
JC
= 4.3°C/W
EXPOSED PAD (PIN 25) IS SGND
(MUST BE SOLDERED TO PCB)
The
● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.3V, V
SHDN
= V
IN
, unless otherwise noted. (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Quiescent Current V
SHDN
= 3.3V, V
CTRL4
= 0V, Not Switching ● 710 mA
V
SHDN
= V
CTRL4
= 0V, In Shutdown ● 01 µA
Input Voltage Range V
CC
Pin ● 2.6 16 V
AV
DD
Feedback Voltage FB1 Pin ● 1.225 1.25 1.275 V
AV
DD
Feedback Pin Bias Current (FB1) FB1 Pin (Note 3) 15 60 nA
AV
DD
Feedback Voltage for Power Good Signal FB1 Pin Voltage as a Percent of Nominal Voltage ● 95 97 100 %
V
OFF
Feedback Voltage NFB2 Pin –160 –150 –140 mV
V
OFF
Feedback Pin Bias Current (NFB2) NFB2 Pin (Note 3) 25 60 nA
V
ON
Feedback Voltage FB3 Pin 1.225 1.25 1.275 V
V
ON
Feedback Pin Bias Current (FB3) FB3 Pin (Note 3) 25 60 nA
LED Feedback Voltage FB4 Pin, V
CTRL4
= 3.3V ● 190 200 210 mV
LED Feedback Pin Bias Current (FB4) FB4 Pin (Note 3) 20 60 µA
LED Feedback Voltage with Dimming FB4 Pin, V
CTRL4
= 1V 85 95 105 mV
ELECTRICAL CHARACTERISTICS
24 23 22 21 20 19
7 8 9
TOP VIEW
25
UF PACKAGE
24-LEAD (4mm × 4mm) PLASTIC QFN
10 11 12
6
5
4
3
2
1
13
14
15
16
17
18
PGND23
SW3
D3
V
OUT3
FB3
NFB2
LED1
LED2
D4
FB4
FB1
PGOOD
SW2
D2
V
CC
PGND14
SW1
SW4
SHDN
CTRL4
CT
AGND
SS1
SS4
UF PART
MARKING
1942
LT1942
3
1942fb
LED1-LED2 Current Matching Current Into Each Pin = 20mA, V
LED1
= V
LED2
0 1.5 %
Current Into Each Pin = 20mA, |V
LED1
-V
LED2
| = 1V 1 2.5 %
LED1 Voltage 20mA Into Pin, V
LED2
= 2V, FB4 = 0 1 1.2 V
LED2 Voltage 20mA Into Pin, V
LED1
= 2V, FB4 = 0 1 1.2 V
LED1, LED2 Maximum Current Into Either Pin, V
LEDX
< 1.5V, FB4 = 0 35 mA
LED1, LED2 Leakage Current V
SHDN
= 0V, V
LEDX
= 45V ● 1 µA
AV
DD
Maximum Duty Cycle SW1 Pin 88 93 %
V
OFF
Maximum Duty Cycle SW2 Pin 75 86 %
V
ON
Maximum Duty Cycle SW3 Pin 75 86 %
LED Maximum Duty Cycle SW4 Pin 88 93 %
AV
DD
Switch Current Limit at Minimum DC (SW1) SW1 Pin (Note 4) 150 200 250 mA
AV
DD
Switch Current Limit at Maximum DC (SW1) SW1 Pin (Note 4) 80 140 200 mA
V
OFF
Switch Current Limit at Minimum DC (SW2) SW2 Pin (Note 4) 50 80 110 mA
V
OFF
Switch Current Limit at Maximum DC (SW2) SW2 Pin (Note 4) 30 60 90 mA
V
ON
Switch Current Limit at Minimum DC (SW3) SW3 Pin (Note 4) 50 80 110 mA
V
ON
Switch Current Limit at Maximum DC (SW3) SW3 Pin (Note 4) 30 60 90 mA
LED Switch Current Limit at Minimum DC (SW4) SW4 Pin (Note 4) 550 750 900 mA
LED Switch Current Limit at Maximum DC (SW4) SW4 Pin (Note 4) 450 600 850 mA
V
OFF
Schottky Diode Forward Drop D2 Pin, I = 60mA 0.65 V
V
OFF
Schottky Diode Leakage Current D2 Pin, V
D2
= –36V ● 1 µA
V
ON
Schottky Diode Forward Drop D3 Pin, I = 60mA 0.65 V
V
ON
Schottky Diode Leakage Current V
D3
= 36V, SW3 = 0V, Output Disconnect PNP Off ● 1 µA
LED Schottky Diode Forward Drop I = 250mA 0.75 V
LED Schottky Diode Leakage Current V
D4
= 36V, SW4 = 0V ● 1 µA
Switching Frequency 0.8 1 1.2 MHz
SHDN Pin Current V
SHDN
= 3V ● 70 100 µA
V
SHDN
= 0V 20 30 nA
CTRL4 Pin Current V
CTRL4
= 3V ● 30 60 µA
V
CTRL4
= 0V –60 –150 nA
SW1-SW4 leakage Current V
SWX
= 36V ● 0.01 1 µA
SW1 V
CESAT
I
SW1
= 100mA (Note 5) 200 300 mV
SW2 V
CESAT
I
SW2
= 40mA (Note 5) 150 250 mV
SW3 V
CESAT
I
SW3
= 40mA (Note 5) 150 250 mV
SW4 V
CESAT
I
SW4
= 400mA (Note 5) 280 400 mV
SS1 Charging Current V
SS
= 0.5V 1 3 5 µA
SS4 Charging Current V
SS
= 0.5V 1 3 5 µA
SHDN Input Voltage High 1V
SHDN Input Voltage Low 0.4 V
CTRL4 Input Voltage High 0.25 V
CTRL4 Input Voltage Low 0.1 V
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.3V, V
SHDN
= V
IN
, unless otherwise noted. (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
ELECTRICAL CHARACTERISTICS
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16

MIC5319-2.8YML-TR

Mfr. #:
Buy MIC5319-2.8YML-TR
Manufacturer:
Microchip Technology / Micrel
Description:
LDO Voltage Regulators 500mA uCap Ultra-Low Dropout, High PSRR LDO Regulator
Lifecycle:
New from this manufacturer.
Delivery:
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