SGM2005-1.8 SGMICRO [Shengbang Microelectronics Co, Ltd], SGM2005-1.8 Datasheet - Page 8

• Manufacturer Part Number: SGM2005-1.8
• Description: Low Power, Low Dropout, 150mA, RF - Linear Regulators
• Manufacturer: SGMICRO [Shengbang Microelectronics Co, Ltd]

Application Notes
When LDO is used in handheld products, Attention must be paid to voltage spike which would damage
SGM2005. In such applications, voltage spike will be generated at changer interface and V
pin of USB
BUS
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:
Vcc
IN
V
V
Input
SGM2005
OUT
OUT
1uF
C
C
4.7uF
1
BZM55B5V6
2
GND
EN
BP
0.01uF
Control
SGM2005
８