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BU9829GUL-W Fiches technique(PDF) 11 Page - Rohm |
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BU9829GUL-W Fiches technique(HTML) 11 Page - Rohm |
11 / 17 page Technical Note 11/16 BU9829GUL-W www.rohm.com 2010.09 - Rev.A © 2010 ROHM Co., Ltd. All rights reserved. ● EEPROM part 1. Hardware Connection of EEPROM EEPROM may have malfunction owing to noise signal for input pin, and movement in the low voltage region at power ON/OFF. These malfunctions may occur, especially at min voltage limit of EEPROM or below. To avoid this, please note about hardware connection showed as follows. 1.1 Input Terminals Input equivalent circuits of CSB, SCK and SI are showed Fig.47, 48. Input terminal is connected between CMOS schmitt trigger input circuit and input protection circuit. These pin are not pull up or pull down, therefore please don’t input Hi-Z in use. And please make CSB “HIGH” in the low voltage region at power ON/OFF. If CSB is "LOW" at power ON/OFF, malfunction may occur. To make other input terminals pull up or pull down is recommendable. 1.2 Output Terminals Output equivalent circuit of so is showed Fig.49. This output terminal is 3 states buffer. The data is output from so at output timing by READ command, so is Hi-z except this timing. If EEPROM malfunction occur by Hi-z input of the microcontroller port connected with so, please make so pull up or pull down. If it doesn’t affected the microcontroller movement to make so open, it is no problem. Load capacity of so disturb high speed movement of EEPROM. If this load capacity is 100pF or below, BU9829GUL-W can move in 2.5MHz (Vcc1=1.6V~1.8V) or 5MHz (Vcc1=1.8V~3.6V) 1.3 Input pin pull up, pull down resistance The design method of pull up/pull down resistance for input and output are as follows. 1.3.1 Pull up resistance Rpu of input terminals CSB Fig.47 CSB terminals equivalent circuit SCK, SI SO Example) When Vcc=5V, VILE=1.5V, VOLM=0.4V, IOLM=2mA, from the equation①, ・ VILE : EEPROM VIL specifications ・ VOLM : Microcontroller VOL specifications ・ IOLM : Microcontroller IOL specifications Fig.50 Input terminal pull up resistance ∴ Rpu ≧ 2.3[kΩ] Rpu ≧ 5-0.4 2×10 -3 With the value of Rpu to satisfy the above equation, VOLM becomes 0.4V or below, and with VILE(=1.5V), the equation ② is also satisfied. Rpu ≧ VOLM ≦ VILE …② …① VCC-VOLM IOLM Microcontroller EEPROM “L” input “L” output Rpu IOLM VOLM VILE Fig.48 SCK,SI terminals equivalent circuit Fig.49 SO terminals equivalent circuit |
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