DTU-1705 USB Tester



Official specifications:

• Input voltage: DC 4 - 30V
• Input current: DC 0 - 5A
• Voltage resolution: 0.0001V
• Current resolution: 0.0001A
• Voltage accuracy: 0.1% + 2
• Current accuracy: 0.1% + 2
• Power consumption: 7-11mA
• Internal resistance: 55 - 65mOhm
• Capacity counter: 0 - 9999.9Ah (Resolution: 0.0001Ah)
• Power counter: 0 - 9999.9Wh (Resolution: 0.0001Wh)
• Timer range: 0 - 999mins
• Interface: USB-A, TYPE-C, Micro USB
• Logger capacity: 100 group
• Log rate: 0 - 60min
• Protocol: QC2.0, QC3.0, Apple, HuaWei, Samsung
• Size: 82mm x 33mm x 15mm

This is a high resolution USB meter.



I got the meter in a cardboard box, with specification on the back. It contained the meter and a instruction sheet in English and
Chinese.



The user interface is fairly simple, short presses on the two button changes screen or steps a value up/down, longer presses will activate/cancel configuration.











Display and functions




The main screen with voltage, current and power. There is also the output status because this tester can turn off output on under voltage, over voltage, under current, over current and time.



Voltage and current with power, capacity and time.



Protocol analyzer, shown detected protocol, voltage on data lines and load equivalent resistance.



Calculate resistance in a cable, this requires a constant load and a stable usb supply. Then the reference voltage can be stored with load and without cable, adding the cable when reference is stored will show the resistance in cable and connectors.



The charting function is designed to show a full charge curve, the fastest update rate is once a minute. The curve is saved.



There are a couple of configuration screens, Voltage, current, time out, log rate, back light, factory reset.



Measurements

• USB-C output will not be triggered when this device is used.
• USB-C output cannot be triggered from another device.
• The usb meter uses about 11mA current with backlight on.
• The internal resistance is about 0.110 ohm (This includes both connectors).
• Usb meter will remember measured values when power is removed.
• Backlight timeout can be adjusted in 20s, 40s, 60s, always
• Voltage display is easily within the rated 0.1% when no current is flowing.
• Current display is within the rated 0.1% up to 3A, but more like 0.5% at 5A
• Curve update is in minutes, i.e. the curve is more than an hour at fastest setting

The voltage display is very precise with no current flowing, but there is on digit too much for the precision.



The current display is also very precise up to 3A, then the precision drops a bit.



M1: 43.5°C, HS1: 71.6°C



M1: 46.9°C, HS1: 67.0°C

The above IR photo was taken after 30minutes with 5A.
The current varies with temperature, I got 0.34% change after 30 minutes with 5A.



Tear down



It was easy to open with four screws. Notice the two buttons are not the same, this prevents assembly faults.



The meter is based around a microprocessor (MM32F031K6T Arm M0), with support from a EEPROM (U4: 24C08AN), a ADC for voltage (U1: CS1237 24 bit) and a ADC for current (U6: marked CAUS). The current is measured across a 0.012ohm (12mOhm) resistor.



On this side is the voltage regulator (U3: XC6203A 3.3V) and the transistor used to connected/disconnect the usb output (U2)









Conclusion

A precise usb meter with some extra functions like cable resistance, protocol analysis and disconnect. The chart can be rather useful with the slow time scale, it will show the full charge curve for a phone or tablet. The USB-C functions do not really work.
I like the used interface, it is fairly easy to use.



Notes

For these USB meters I used precise equipment (Keithley: DMM7510, 2280S, Keysight: 34470A).

How do I make the test