ESD & EOS Production Solutions for Battery Pack

2021/12/13

Handheld electronic products become smaller and smarter thanks to the rapid advancement of micro-electronic technology. Semiconductor firms spend a lot of time and efforts to incorporate more transistors in SoC for more and better functions, while low-voltage power supply solutions are introduced to reduce the power consumption of chips, thus leading to more advanced CMOS manufacturing processes (Fig. 1). Of course, smaller manufacturing process means smaller clearance between CMOSs, making them vulnerable to ESD bombardment. 


Figure 1. Evolution of microprocessor chips

Figure 1. Evolution of microprocessor chips


In the real world, we found lots of SoCs fail because of electrostatic field or discharge (ESD), and the failure leads to product function errors or data loss, reduced reliability of equipment, or even EOS damage in the chips. Most of the firms bring in IEC61000-4-2 (electrostatic discharge standard at the system level) to test the stability and reliability of products for better product quality. 


The booming of consumer products is largely indicated by the surge in the demands for Li-ion batteries used in cell phones, tablets and PCs. The electrostatic discharge test for battery packs has to satisfy customers’ basic requirements (Contact ±8kV Air ±15kV). Therefore, how are we going to choose a TVS for more stable work environment? Let’s take the batteries in cell phones and tablets for an example. TVS elements require ultra-small package due to the limited space on the charging/discharging management PCB. Also considering the long standby time of batteries, TVS elements require leakage current to be less than 1mA. On top of that, the clamping voltage of TVS has to be as low as possible to reduce ESD impacts. Based on the above (small package, low leakage current and low ESD clamping voltage), Amazing Microelectronic comes up with the best protection solution for battery production board, the AZ5A75-01F. This TVS adopts the 0201 (DFN0603P2Y) package that features leakage current < 1mA (at the work voltage of 5V). It is clear in the TLP diagram that the clamping voltage is approximately 12V with the system tested at 8kV (Fig. 3). AZ5A75-01F is designed for the ESD production for ports IIC and ID on battery production board (Fig. 2). 


Figure 2. Li battery production board TVS application

Figure 2. Li battery production board TVS application

Figure 3. AZ5A75-01F TLP measurements

Figure 3. AZ5A75-01F TLP measurements


In response to the plugging and unplugging of Li battery for charging and the surge caused by unstable system power supply, a TVS with surge protection is considered at the beginning of design stage. The surge_Ipp parameter in the specifications says it all (the maximum conducting capability for 8/20ms current wave test). Amazing Microelectronic launched the AZ5A85-01B in the same 0201 package, which features not only better ESD protection (clamping voltage 6V@8kV) but also greater surge protection (Table 1): 

PN.
Vrwm
Package
Vcl_ESD@8kV
Surge_Ipp
AZ5A75-01F
5V
0201
12V
3A
AZ5A85-01B
5V
0201
6V
16A

Table 1. Key parameters of AZ5A75-01F and AZ5A85-01B


As the information and communication technology evolves in the speed of light, product design concepts and applications pop out every day. Mark Zuckerberg points out that intelligent wearable devices and meta-verse equipment are going to take the center stage, and we are going to see more in-depth studies and R&D efforts invested in new businesses. Apart from owing how powerful it is, we need to pay attention to whether enough ESD production is provided in the internal circuit. Amazing Microelectronic’s TVS AZ5C23-01B and AZ5C25-01B in ultra-small 01005 package satisfy products with greater requirement for space (Table 2). 


PN.
Vrwm
Package
Vcl_ESD@8kV
Surge_Ipp
AZ5C23-01B
3.3V
01005
5.5V
NA
AZ5C25-01B
5V
01005
5.8V
10A

Table 2. Specifications of TVS in 01005 ultra-small package

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