Analysis of Motorola 168VA mobile phone car charger

There is a car charger on the market suitable for Motorola 168VA mobile phones. It is small and can be directly inserted into the car cigarette lighter socket for use or charging. Since the circuit diagram is not attached, maintenance is inconvenient. The measured circuit diagram is for reference during maintenance. The UTC34063 in the picture is an eight-pin dual-in-line IC, which is a single-chip step-up and step-down DC conversion control IC. There are temperature compensator, comparator, high current output switch and other units inside the IC. The oscillation frequency is 100KHz. The actual measured data is shown in the table below. Pin number...on-circuit resistance value...voltage (V)...red test (KΩ) black test (KΩ) 1...4.1... .8.2 .......12 2 ......0.8...... 7.8...... 8.28 3 ......5.8 ......22 ... ....0.65 4 ....0 ...........0......... 0 5 .....1..... 1...1.26 6...4.2...8.2...12 7...4.2...8.2... ....12 8 .....5.......... 10 ....10.6 Note: (1) The on-circuit resistance is measured with a 500-type multimeter; (2) The voltage value is Input DC 12V, measure with DT890C+ digital meter in no-load state