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| LP3950 Datasheet, PDF (14/38 Pages) National Semiconductor (TI) – Color LED Driver with Audio Synchronizer | |||
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LP3950
SNVS331C â NOVEMBER 2004 â REVISED APRIL 2013
Magnetic Boost DC/DC Converter Electrical Characteristics(1)(2)
Symbol
Parameter
Conditions
Min
ILOAD
Load Current
3.0V ⤠VIN ⤠4.5V
VOUT = 5.0V
0
VOUT
Output Voltage Accuracy
1.0 mA ⤠ILOAD ⤠300 mA
(FB Pin)
3.0V ⤠VIN ⤠4.5V
â5
VOUT = 5.0V (target value), autoload OFF
Output Voltage
(FB Pin)
1.0 mA ⤠ILOAD ⤠300 mA
3.0V < VIN < 5.0V + V(SCHOTTKY),
autoload OFF
RDSON
fPWF
Switch ON Resistance
PWM Mode Switching
Frequency
1.0 mA ⤠ILOAD ⤠300 mA
VIN > 5V + V(SCHOTTKY)
VDD1,2 = 2.8V, ISW = 0.5A
RT = 82 kâ¦
freq_sel[2:0] = 1XX
Frequency Accuracy
2.7 ⤠VDD1,2 ⤠2.9
â6
RT = 82 kâ¦
â9
tPULSE
Switch Pulse Minimum
Width
No Load
tSTARTUP Startup Time
ICL_OUT SW Pin Current Limit
700
500
www.ti.com
Typ
Max Units
300
mA
+5
%
5.0
V
VINâV(SCHOTTKY)
0.4
2.0
±3
25
15
800
0.7
+6
+9
900
1000
V
â¦
MHz
%
ns
ms
mA
(1) Limits in standard typeface are for TJ = +25°C. Limits in boldface type apply over the operating ambient temperature range (â40°C ⤠TA
⤠+85°C). Unless otherwise noted, specifications apply to Figure 2 with: VDD1 = VDD2 = VDDA = 2.8V, CVDD1 = CVDD2 = CVDDA = CVDDIO =
100 nF, COUT = CIN = 10 µF, CVREF = 100 nF, L1 = 4.7 µH and fBOOST = 2.0 MHz.
(2) Low-ESR Surface-Mount Ceramic Capacitors are used in setting electrical characteristics.
Boost Standby Mode
User can set the boost converter to STANDBY mode by writing the register bit EN_BOOST low when there is no
load to avoid idle current consumption. When EN_BOOST is written high, the converter starts in PFM (Pulse
Frequency Modulation) mode for 10 ms and then goes to PWM (Pulse Width Modulation ) mode. All RGB
outputs are off during the 10 ms delay.
Boost Output Voltage Control
User can control the boost output voltage by eight-bit boost output voltage register according to the following
table.
BOOST[7:0]
Register 0D'h
Binary
Hex
0000 0000
00
0000 0001
01
0000 0011
03
0000 0111
07
0000 1111
0F
0001 1111
1F
0011 1111
3F
0111 1111
7F
1111 1111
FF
BOOST Output Voltage
(typical)
4.10
4.25
4.40
4.55
4.70
4.85
5.00 Default
5.15
5.30
14
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Copyright © 2004â2013, Texas Instruments Incorporated
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