HEF4521B

INTEGRATED CIRCUITS DATA SHEET For a complete data sheet, please also download: The IC04 LOCMOS HE4000B Logic Family Specifications HEF, HEC The IC04 LOCMOS HE4000B Logic Package Outlines/Information HEF, HEC HEF4521B MSI 24-stage frequency divider and oscillator Product specification File under Integrated Circuits, IC04 January 1995 Philips Semiconductors Product specification 24-stage frequency divider and oscillator DESCRIPTION The HEF4521B consists of a chain of 24 toggle flip-flops with an overriding asynchronous master reset input (MR), and an input circuit that allows three modes of operation. The single inverting stage (I2/O2) will function as a crystal oscillator, or in combination with I1 as an RC oscillator, or as an input buffer for an external oscillator. Low-power HEF4521B MSI operation as a crystal oscillator is enabled by connecting external resistors to pins 3 (VSS’) and 5 (VDD’). Each flip-flop divides the frequency of the previous flip-flop by two, consequently the HEF4521B will count up to 224 = 16777216. The counting advances on the HIGH to LOW transition of the clock (I2). The outputs of the last seven stages are available for additional flexibility. Fig.1 Functional diagram. FAMILY DATA, IDD LIMITS category MSI See Family Specifications January 1995 2 Philips Semiconductors Product specification 24-stage frequency divider and oscillator COUNT CAPACITY HEF4521B MSI OUTPUT O18 O19 O20 O21 Fig.2 Pinning diagram. O22 O23 O24 HEF4521BP(N): 1...