LP3954 Datasheet, PDF (10/60 Pages) National Semiconductor (TI) – Advanced Lighting Management Unit

LP3954
SNVS340D – JUNE 2005 – REVISED MARCH 2013
MAGNETIC BOOST DC/DC CONVERTER ELECTRICAL CHARACTERISTICS
I_LOAD
V_OUT
RDS_ON
f_PWF
t_PULSE
t_STARTUP
I_{SW_MAX}
Parameter
Load Current
Output Voltage Accuracy
(FB Pin)
Output Voltage
(FB Pin)
Switch ON Resistance
PWM Mode Switching Frequency
Frequency Accuracy
Switch Pulse Minimum Width
Startup Time
SW Pin Current Limit
Test Conditions
3.0V ≤ V_IN
V_OUT = 5V
3.0V ≤ V_IN
V_OUT = 4V
3.0V ≤ V_IN ≤ V_OUT - 0.5
V_OUT = 5.0V
1 mA ≤ I_LOAD ≤ 300 mA
V_IN > 5V + V_(SCHOTTKY)
V_DD1,2 = 2.8V, I_SW = 0.5A
RT = 82 kΩ
freq_sel[2:0] = 1XX
2.7 ≤ VDDA ≤ 2.9
RT = 82 kΩ
no load
Boost startup from STANDBY
Min
Typ
0
0
−5
V_IN–V_(SCHOTT
KY)
0.4
2
−6
±3
−9
25
10
700
800
550
Max
300
400
+5
0.8
+6
+9
900
950
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Unit
mA
%
V
Ω
MHz
%
ns
ms
mA
BOOST STANDBY MODE
User can stop the Boost Converter operation by writing the Enables register bit EN_BOOST low. When
EN_BOOST is written high, the converter starts for 10ms in PFM mode and then goes to PWM mode.
BOOST OUTPUT VOLTAGE CONTROL
User can control the boost output voltage by boost output 8-bit register.
Boost Output [7:0]
Register 0DH
Bin
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)
4.00
4.25
4.40
4.55
4.70
4.85
5.00 Default
5.15
5.30
10
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