Who is the manufacturer of this DIP and is there any datasheet or documentation for it? Top marking FD633D 1230
It's made by Fuda Hisi Microelectronics in Fuzhou, China. A CMOS LED and key scan device.
Introduction: FD633 is a special LED driver control circuit with keyboard scanning circuit interface. Internally integrated MCU input and output control digital interface, data latch, LED driver, keyboard scanning, brightness adjustment and other circuits. The chip has stable performance, reliable quality and strong anti-interference ability, and can be adapted to the application occasions of long-term continuous work for 24 hours.
 • Adopt power CMOS process
 • Display mode: 7-segment×5 digits, or 8-segment×4 digits
 • Key scan: 7×1
 • Brightness adjustment circuit (duty cycle 8-level adjustable)
 • Three-wire string Line interface (CLK, STB, DI/O)
 • Oscillation mode: built-in RC oscillation (frequency is 450KHz±5%)
 • built-in encryption function
 • power supply: support 3V-5.5V power supply voltage, typical value 3.3V
 • Adopt DIP18, SOP20 package

I don't see a working datasheet link.