LT1942(RevA) Ver la hoja de datos (PDF) - Linear Technology
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Fabricante
LT1942 Datasheet PDF : 16 Pages
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LT1942
TYPICAL APPLICATIO S
VIN
3V TO 4.2V
VON
10V
2mA
C5
22µF
R5
C3
698k
0.22µF
16V
R6
100k
C2
0.22µF
16V
VOFF
–10V
2mA
R4
10k
R3
665k
VIN
SHUTDOWN
C5 0.1µF 16V
L5 47µH
C6
L2 47µH
LED CONTROL
LED CONTROL VOLTAGE LED CURRENT
>2.5V
20mA
0.25V
<0.1V
2.5mA
DISABLED
L1
22µH
D1
L3 22µH
D3 SW3
FB3
PGND23
VCC
SW1
FB1
PGND14
PGOOD
R1
301k
R2
100k
4.7pF
C1
4.7µF
6.3V
M1
PMOS
R8
1M
AVDD
5V
40mA
C4
4.7µF
25V X5R
20mA 20mA
VOUT3
NFB2
LT1942
SW4
L4 33µH
VIN
D4
D2
LED1
SW2
LED2
SHDN SGND/
CTRL4 AGND SS1
FB4
SS4 CT
C7
0.1µF
C8
0.1µF
C9
0.1µF
R7
4.99Ω
1942 F04a
C1 TO C9: X5R OR X7R
D1: CMDSH-3 CENTRAL SEMICONDUCTOR
L1: 22µH MURATA LQH32CN220K53
L2, L5: 47µH TAIYO YUDEN LB2012B470
L3: 22µH TAIYO YUDEN LB2012B220
L4: 33µH SUMIDA CDPH4D19-330MC
M1: Si2301BDS SILICONIX
Figure 4. TFT Bias (5V, 10V, –10V) and White LED Backlight Supply from Single Li-Ion Cell
Efficiency
90
AVDD LOAD = 40mA
VOFF LOAD = 2mA
85 VON LOAD = 2mA
80
VIN = 4.2V
75
VIN = 3.6V
VIN = 3V
70
65
60
5 10 15 20 25 30 35 40
TOTAL LED CURRENT (mA) 1942 F04b
TFT Power Supply Sequencing
AVDD Transient Response, ILOAD Stepped from
30mA→40mA→30mA
VAVDD
5V/DIV
VOFF
10V/DIV
VON
10V/DIV
VSHDN
1V/DIV
14
2ms/DIV
1942 F04c
VAVDD
20mV/DIV
AC-COUPLED
ILI
50mA/DIV
100µs/DIV
1942 F04d
1942fa
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