Did the chip get damaged due to the wrong power connection during programming? The voltage of the target board and the programmer does not match? The triple power supply solution of OPTEEQ SG400E from OPTEEQ Technologies can help you solve the power supply problem during programming!

1. Why is the power supply mode so critical?

SG400E provides three power supply modes when programming chips: programmer power supply, external power supply, and voltage follower.

Impact of power supply mode：

• ✅ Chip safety (overcurrent/overvoltage risk)
• ✅ Signal stability (I/O level matching)
• ✅ System compatibility (self-powered/unpowered target board)

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2. Detailed explanation of 3 power supply modes

2.1 Programmer Power Supply

As the name implies, the programmer supplies power to the target chip. In this mode:

⚡I/O port power supply: provided by SG400E according to the voltage setting of the project.

⚡Target board power supply: provided by SG400E.

Wiring in the programmer power supply mode:

🔗 Programmer VCC and target board VCC: connected✅

🔗 Programmer I/O and target board I/O: connected✅

🔗 Target board external power supply: disconnected❌

⭕It is important to note that:

1. Some chips need to control the output voltage, so they must be powered by a programmer during programming. The relevant precautions will be explained in the corresponding chip option description document.
2. The maximum total output current of a single channel of the programmer (I total = I VCC+ I IO) cannot exceed 350mA.

2.2 External Power Supply

External power supply means that the target board is powered by an external power supply, and the programmer only powers the I/O port. In this mode:

⚡I/O port power supply: provided by SG400E according to the voltage set in the project.

⚡Target board power supply: provided by an external power supply.

Wiring in external power supply mode:

🔗 Burner VCC and target board VCC: disconnected❌

🔗 Burner I/O and target board I/O: connected✅

🔗 Target board external power supply: connected✅

2.3 Voltage Follower

Voltage following means that both VCC and I/O ports are powered by external power. In this mode:

⚡I/O port power supply: The I/O port voltage automatically follows the target board VCC voltage.

⚡Target board power supply: Provided by external power supply.

Wiring in voltage follower mode:

🔗 Burner VCC and target board VCC: connected✅

🔗 Burner I/O and target board I/O: connected✅

🔗 Target board external power supply: connected✅

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3. Summary

Mode	VCC Power Supply	I/O Power Supply	VCC Wiring	I/O Wiring	External Power Supply
Programmer Power Supply	SG400E	SG400E	Connected	Connected	Disconnected
External Power Supply	Target Board External Power Supply	SG400E	Disconnected	Connected	Connected
Voltage Follow	Target Board External Power Supply	Target Board External Power Supply	Connected	Connected	Connected

FAQs

Q: The target board has a power supply, which mode should I choose?

A: Give priority to external power supply mode, disconnect the VCC connection of the programmer, and avoid double-side power supply.

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Q: When programming, it shows that VCC has no voltage. How to check?

A: 1. Check the power supply settings in the project settings → Check if the voltage follower is selected but the VCC is not connected to the target board. 2. Check if the target board needs an ignition signal, whether there is a watchdog on the target board, etc. that requires special processing.