LP3933 Datasheet, PDF (9/18 Pages) National Semiconductor (TI) – Lighting Management System for Six White LEDs and Two RGB or FLASH LEDs

Magnetic Boost DC/DC Converter (Continued)
Boost Converter Topology
20080528
Magnetic Boost DC/DC Converter Electrical Characteristics
Symbol
Parameter
Conditions
Min
I_LOAD
V_FB
RDS_ON
Load Current
3.0V ≤ V_IN ≤ 4.5V
0
V_OUT = 5V
Output Voltage
1 mA ≤ I_LOAD ≤ 300 mA
Accuracy (FB Pin)
3.0V ≤ V_IN ≤
−5
V_OUT − 0.5V
V_OUT = 5V
Voltage at FB Pin
(Boost Converter
1 mA ≤ I_LOAD ≤ 300 mA
3.0V < V_IN < 5V +
Output Voltage)
V_(SCHOTTKY)
1 mA ≤ I_LOAD ≤ 300 mA
> V_IN 5V + V_(SCHOTTKY)
Switch ON Resistance V_{DD1, 2} = 2.775V, I_SW =
0.5A
f_PWF
PWM Mode Switching
Frequency
RT = 82 kΩ
Frequency Accuracy
2.65 ≤ V_{DD1, 2} ≤ 2.9
−6
RT = 82 kΩ
−9
t_STARTUP
Startup Time
I_{CL_OUT}
SW Pin Current Limit
670
530
Typ
5
V_IN– V_(SCHOTTKY)
0.4
1
±3
25
800
Max
300
+5
0.7
+6
+9
915
995
Units
mA
%
V
V
Ω
MHz
%
ms
mA
Boost Standby Mode
User can set the Boost Converter to STANDBY mode by writing the register bit EN_BOOST low. When EN_BOOST is written
high, the converter starts for 10 ms in PFM mode and then goes to PWM mode.
9
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