Converting STK11C48 to STK12C68 Introduction r u ST si K1 ng 2 C C6 Y1 8 4E is 25 in N 6L R A ND in st St ea at d us of . ST K1 2C 68 . This document provides guidance on converting a design that is currently using the STK11C48 to the Simtek recommended part STK12C68. Feature set and limitations of the STK11C48 Function Category STK11C48 Autostore Software store Software recall Not allowed Yes Yes Package Comparison STK12C68 Wired to disallow autostore Yes Yes The 600 mil dip package is available in the STK12C68 and the STK11C68. Other packages that take less PCB area also exist such as 300 mil CDIP/PDIP and the 350 mil SOIC. Package PKG Code S STK11C48 Available STK12C68 Available 600 mil pdip -- 28 pin 300 mil pdip -- 28 pin 300 mil cdip -- 28 pin W P C Not available Available Available Available Available Available on si de 350 mil SOIC – 28 pin Notes Surface mount – smallest PCB area Through hole Through hole Through hole C Issues to consider during the conversion The key difference is that the STK11C48 has been internally configured to disable the autostore function and does not use a 68uf capacitor. The STK12C68 will be wired in VCAP power mode to select non-autostore configuration. Also, the new HSB signal is unused. All other pins have the same function. Only software store is used to store the part. Recall is automatic on power up and also may be activated by software sequence. Application Note Number MA0017 0.0 Schematic changes for conversion: The key difference is that the STK11C48 is equivalent (but smaller) to an STK12C68 wired in VCAP power mode to select no autostore. To do this, the power must be supplied to the VCAP pin and NOT applied to the VCCx pin (which can be either open or at ground). Also, the bypass capacitor moves to the VCAP pin. The choice of package is open with the “S” package being the most area efficient surface mount choice. U1 VCC /READ 22 /CE 20 /WRITE 27 G E W DQ0 DQ1 DQ2 DQ3 DQ4 DQ5 DQ6 DQ7 11 12 13 15 16 17 18 19 DQ0 DQ1 DQ2 DQ3 DQ4 DQ5 DQ6 DQ7 C1-bypass 0.1 uF . A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 68 10 9 8 7 6 5 4 3 25 24 21 from power plane +5v VSS 14 STK11C48 Before Conversion schematic r u ST si K1 ng 2 C C6 Y1 8 4E is 25 in N 6L R A ND in st St ea at d us of . ST K1 2C A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 28 must use gnd plane In this conversion, old bypass capacitor C1 is moved from +5v on pin 28 to pin 1. It is essential that pin 28 be left OPEN and system power (+5v) is now connected to pin 1 (VCAP). The new signal /HSB is left open and unused. This will configure the STK12C68 into a non-autostore part. The storage capacitor is not needed since autostores are deselected. Software stores use system power to complete commanded stores. The extra address pins ( A11 and A12) are tied inactive to ground. 28 MUST LEAVE OPEN 11 12 13 15 16 17 18 19 DQ0 DQ1 DQ2 DQ3 DQ4 DQ5 DQ6 DQ7 C on si de MUSTCONNECT SYSTEM POWER HERE +5v U1 1 VCAP VCCx closest to pin Moved from VCC A0 10 A0 DQ0 A1 C1-bypass 9 DQ1 0.1uF A2 8 A1 A2 DQ2 A3 7 A3 DQ3 A4 6 A4 DQ4 A5 5 A5 DQ5 A6 4 A6 DQ6 A7 3 DQ7 A8 25 A7 A8 A9 24 A10 21 A9 A10 23 2 A11 A12 not used 26 /READ 22 HSB G /CE 20 /WRITE 27 E W VSS 14 STK12C68-W45I After Conversion schematic must use gnd plane On the next page, pin by pin comparisons of the two show all pins are the same except for the bypass capacitor moving to pin 1 and connected to system power, +5v. Pin 28 must now be unpowered and open. Application Note Number MA0017 0.0 Corresponding pin Connections Pin for pin comparison of the two parts is given in the table below: . r u ST si K1 ng 2 C C6 Y1 8 4E is 25 in N 6L R A ND in st St ea at d us of . ST K1 2C 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 de si on A12 A7 A6 A5 A4 A3 A2 A1 A0 DQ0 DQ1 DQ2 VSS DQ3 DQ4 DQ5 DQ6 DQ7 E# A10 G# A11 A9 A8 HSB W# VCCX Must connect 0.1UF BYPASS and hook to system power +5v Connect to ground, (unused address) “ “ “ “ “ “ “ “ “ “ “ “ “ “ “ “ “ “ “ “ Connect to ground, (unused address) “ “ LEAVE OPEN UNUSED No change This pin now must be OPEN and NOT connected to +5v C A12 A7 A6 A5 A4 A3 A2 A1 A0/ DQ0 DQ1 DQ2 VSS DQ3 DQ4 DQ5 DQ6 DQ7 E# A10 G# A11 A9 A8 NC W# VCC Comments 68 STK11C48 STK12C68 Pin NAME NAME NC VCAP 1 Application Note Number MA0017 0.0