The name of the iPhone 5/5C/5S charger is A1443. The specific product parameters are: input AC100～240V, 50Hz/60Hz, 0.15A; output 5.0V@1A, and the altitude is below 2000m. The charger is compact and compact. With the help of colleagues, I spent a lot of time to disassemble my iPhone5 original charger and see its circuit truth.
1, a circuit diagram after careful testing, analysis, and finally "difficult" to anti depicted a circuit diagram thereof, as shown in FIG. Since many of these components are very small, often in the 0402 [1] package, the parameters of these components are unknown. The resistance parameter part of the circuit is based on its 3-digit or 4-digit digital (identification method), and some of it is obtained by testing, which may be inaccurate and is for reference only.
[1] 0402 means that the component is 40 mils long, 20 mils wide, and 100 mils = 2.54 mm.
Figure 1 A1443 circuit diagram (labeled rectification and filtering voltage 155V is measured when the mains is depressurized by a 2:1 isolation transformer to AC110V)
 2. When the working waveform is no-load and load (charge the charging treasure, the current is about 1A), the working waveform of the 2 pin of FAN301H and the drain of the switching tube is shown in Fig. 2. At no load, the switching frequency and duty cycle are very low, and there is intermittent oscillation; the heavier the load, the higher the switching frequency. When the load is close to full load, the switching frequency is close to the highest operating frequency (85 kHz), and the duty ratio is also relatively large.
Figure 2 A1443 charger working waveform
In order to give readers a comprehensive understanding of the Apple charger, the following table lists the technical specifications of Apple's three chargers.
3, disassembly diagram charger A1443 internal disassembly diagram shown in Figure 3.
Figure 3 Charger A1443 internal disassembly diagram
 4. Load experiment The author conducted a load test to observe the output voltage and current status.
Note: The following test input voltage is stepped down to AC110V by Chint isolation transformer 2:1.
1
Charge the charging treasure. In order to test the output current, the author uses 0.1Ω on the Nokia charger (there is very little resistance, the error caused by the serial test circuit is small) is connected to the positive lead of the USB, so that only the pressure of the 0.1Ω resistor is measured. Drop, as shown in Figure 4. The output current of the charger (to the charging treasure) is about 867mA (= 86.7mV / 0.1Ω).
Figure 4 The 0.1Ω series connected USB positive lead has a voltage drop of 86.7mV at both ends.
Charging current is 867mA
The multimeter is connected in parallel at both ends of the USB output line, and the measured output voltage is 5.00V. At this time, the charging treasure is being charged, and the charging current is 867mA (see Figure 5).
Figure 5 Load charging treasure, the multimeter measured the output voltage is 5.00V
2
When the load is 10Ω, the multimeter measures the output voltage to 5.05V, the output current is about 505mA, and the output power is 2.55W, as shown in Figure 6.
Figure 6 Load 10Ω, the multimeter measured the output voltage is 5.05V
 3
When the load is 2.5Ω, the multimeter measures the output voltage at 2.98V, the output current is about 1.192A, and the output power is 3.55W, as shown in Figure 7.
Figure 7 Load 2.5Ω, the multimeter measured the output voltage is 2.98V
From the above test results, we can know:
1. The maximum output current of the A1443 charger is 1.2A;
2. The output voltage is 5V at light load, and the output voltage drops when heavy load;
3. The smaller the load resistance, the lower the output voltage, and the output current is slightly lower than the maximum current;
4. The rated current (1A) has the largest output power, and the output power decreases as the load resistance decreases.
From the author's test and analysis, the intensity and volume ratio of the Apple charger is extremely difficult for domestic manufacturers, especially its special-shaped switching transformers. The materials are exquisite, the materials are excellent, the workmanship is fine, and even the Huawei charger is in contact with it. It is also dwarfed. I hope that the above analysis of the author can provide some reference for readers when learning and designing related charging circuits.
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