SG2003 Shengbang Microelectronics, SG2003 Datasheet - Page 9

• Manufacturer Part Number: SG2003
• Description: (SG2003 / SG2004) Linear Regulators
• Manufacturer: Shengbang Microelectronics

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TYPICAL OPERATING CHARACTERISTICS
V
Application Notes
When LDO is used in handheld products, Attention must be paid to voltage spike which would damage
SG2003 and SG2004. In such applications, voltage spike will be generated at changer interface and V
pin of USB interface when changer adapters and USB equipments are hot-inserted. Besides this, handheld
products will be tested on the production line on the condition of no battery. Test Engineer will apply power
from the connector pin which connects with positive pole of the battery. When external power supply is
turned on suddenly, the voltage spike will be generated at the battery connector. The voltage spike will be
very high, it always exceeds the absolute maximum input voltage (6.0V) of LDO. In order to get robust
design. Design Engineer needs to clear up this voltage spike. Zener diode is a cheap and effective solution to
eliminate such voltage spike. For example, BZM55B5V6 is a 5.6V small package Zener diode which can be
used to remove voltage spike in cell phone design. The schematic is shown in below:
IN
= V
OUT(NOMINAL)
6
4
2
0
2
1
0
Input
Vcc
BZM55B5V6
+1V, C
IN
= 1µF, C
Time(10μs/div)
Start Up
OUT
1uF
Control
= 1µF, C
V
V
C
I
IN
OUT
IN
LOAD
= 5V
= C
= 2.5V
= 1mA
C
OUT
BP
1
= 1μF
= 0.01µF, T
IN
EN
A
SG2003/SG2004
= +25℃, unless otherwise noted.
９
GND
BP/FP
0.01uF
V
OUT
C
2
4.7uF
SG2003/A
SG2004/A
V
OUT
BUS