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HEF4541B Dataheets PDF



Part Number HEF4541B
Manufacturers NXP
Logo NXP
Description Programmable timer
Datasheet HEF4541B DatasheetHEF4541B Datasheet (PDF)

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 HEF4541B MSI Programmable timer Product specification File under Integrated Circuits, IC04 January 1995 Philips Semiconductors Product specification Programmable timer DESCRIPTION The HEF4541B is a programmable timer which consists of a 16-stage binary counter, an integrated oscillat.

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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 HEF4541B MSI Programmable timer Product specification File under Integrated Circuits, IC04 January 1995 Philips Semiconductors Product specification Programmable timer DESCRIPTION The HEF4541B is a programmable timer which consists of a 16-stage binary counter, an integrated oscillator to be used with external timing components, an automatic power-on reset and output control logic. The frequency of the oscillator is determined by the external components Rt and Ct within the frequency range 1 Hz to 100 kHz. This oscillator may be replaced by an external clock signal at input RS, the timer advances on the positive-going transition of RS. A LOW on the auto reset input (AR) and a LOW on the master reset input (MR) enables the internal power-on reset. A HIGH level at input MR resets the counter independent on all other inputs. Resetting HEF4541B MSI disables the oscillator to provide no active power dissipation. A HIGH at input AR turns off the power-on reset to provide a low quiescent power dissipation of the timer. The 16-stage counter divides the oscillator frequency by 28, 210, 213 or 216 depending on the state of the address inputs (A0, A1). The divided oscillator frequency is available at output O. The phase input (PH) features a complementary output signal. If the mode select input (MODE) is LOW or HIGH the timer can be used respectively as a single transition timer or 2n frequency divider. Fig.1 Functional diagram. HEF4541BP(N): HEF4541BD(F): HEF4541BT(D): 14-lead DIL; plastic (SOT27-1) 14-lead DIL; ceramic (cerdip) (SOT73) 14-lead SO; plastic (SOT108-1) ( ): Package Designator North America FAMILY DATA, IDD LIMITS category MSI Fig.2 Pinning diagram. See Family Specifications January 1995 2 Philips Semiconductors Product specification Programmable timer HEF4541B MSI Fig.3 Logic diagram. January 1995 3 Philips Semiconductors Product specification Programmable timer PINNING A0, A1 MODE AR MR PH RTC CTC RS address inputs mode select input auto reset input master reset input phase input external resistor connection (Rt) external capacitor connection (Ct) external resistor connection (RS) or external clock input AR H L X X X X FREQUENCY SELECTION TABLE X A0 L L H H A1 L H L H NUMBER OF COUNTER STAGES n 13 10 8 16 f osc n -------- = 2 f out 8 192 1 024 256 65 536 L H X FUNCTION TABLE INPUTS MODE MR L L H L L L PH X X X X X L MODE X X X H L X HEF4541B MSI auto reset disabled auto reset enabled (1) master reset active normal operation selected division to output single-cycle mode (2) output initially LOW, after reset output initially HIGH, after reset Notes 1. For correct power-on reset, the supply voltage should be above 8.5 V. For VDD < 8.5 V, disable the autoreset and connect AR to VDD. 2. The timer is initialized on a reset pulse and the output changes state after 2n-1 counts and remains in that state (latched). Reset of this latch is obtained by master reset or by a LOW to HIGH transition on the MODE input. H = HIGH state (the more positive voltage) L = LOW state (the less positive voltage) X = state is immaterial RC oscillator Timing component limitations The oscillator frequency is mainly determined by RtCt, provided Rt << RS and RSC2 << RtCt. The function of RS is to minimize the influence of the forward voltage across the input protection diodes on the frequency. The stray capacitance C2 should be kept as small as possible. In consideration of accuracy, Ct must be larger than the inherent stray capacitance. Rt must be larger than the LOCMOS ‘ON’ resistance in series with it, which typically is 500 Ω at VDD = 5 V, 300 Ω at VDD = 10 V and 200 Ω at VDD = 15 V. The recommended values for these components to maintain agreement with the typical oscillation formula are: Ct ≥ 100 pF, up to any typical value, 10 kΩ ≤ Rt ≤ 1 MΩ. Typical formula for oscillator frequency: 1 f osc = --------------------------------2, 3 × R t × C t Fig.4 External component connection for RC oscillator; RS ≈ 2 Rt. January 1995 4 Philips Semiconductors Product specification Programmable timer HEF4541B MSI  Ct curve at Rt = 56 kΩ; RS = 120 kΩ. − − − Rt curve at Ct = 1 nF; RS = 2 Rt. Fig.5 RC oscillator frequency as a function of Rt and Ct at VDD = 5 to 15 V; Tamb = 25 °C. January 1995 5 Philips Semiconductors Product specification Programmable timer HEF4541B MSI  Rt = 56 kΩ; Ct = 1 nF; RS = 0. − − − Rt = 56 kΩ; Ct = 1 nF; RS = 120 kΩ. Fig.6 Frequency deviation (∆f) as a function of ambient temperature; referenced at : fosc at Tamb = 25 °C and VDD = 10 V. January 1995 6 Philips Semiconductors Product specification Programmable timer DC CHARACTERISTICS VSS = 0 V Tamb (°C) VDD V Supply current power-on reset enabled (note) Supply voltage for automatic reset initialization (note) Out.


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