HT1621B

HT1621B is the ordering name for the Holtek HT1621B RAM-mapping LCD driver. Package identity needs care with this code: the maker’s HT1621/1621G datasheet (Rev. 3.21) names the bare HT1621B code for 48-pin SSOP and LQFP forms, while the current revision of that series datasheet (Rev. 3.30) keeps the same two-body listing with no package-distinguishing order code - so the bare code alone does not fix which 48-pin body a lot carries, and the package field here lists both rather than guessing one. It drives a 32 × 4 display pattern from an internal display RAM, runs from 2.4 V to 5.2 V, draws an operating current of 150 µA typical and 300 µA maximum at 3 V with the on-chip RC oscillator running and the LCD on (300 µA typical, 600 µA maximum at 5 V), a standby current of 0.3 µA typical and 10 µA maximum at 5 V, and a system clock of 192 kHz minimum, 256 kHz typical and 320 kHz maximum, over -40 °C to +85 °C. The selection point is glass-driving with almost no firmware: a serial-written display RAM and an on-chip oscillator let a small MCU refresh segment LCDs on meters, thermostats and appliance panels without a parallel bus. Selection advice: judge any offer against the Holtek manuals for the bare HT1621B code - clone vendors publish documents under extended codes built on this designation, and those documents were not used here - and confirm the exact 48-pin package (LQFP or SSOP) against the offered lot’s full marking before ordering. Parameters verified against the Holtek HT1621/1621G datasheet Rev. 3.21 (features and DC/AC characteristics) and Rev. 3.30 (package listing).