HD64F3437TFI16V Renesas Electronics America, HD64F3437TFI16V Datasheet - Page 469

• Manufacturer Part Number: HD64F3437TFI16V
• Description: MCU FLASH 60K 100-TQFP
• Manufacturer: Renesas Electronics America

Specifications of HD64F3437TFI16V

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

20.1
20.1.1
Table 20.1 illustrates the principle of operation of the H8/3437F’s on-chip flash memory.
Like EPROM, flash memory is programmed by applying a high gate-to-drain voltage that draws
hot electrons generated in the vicinity of the drain into a floating gate. The threshold voltage of a
programmed memory cell is therefore higher than that of an erased cell. Cells are erased by
grounding the gate and applying a high voltage to the source, causing the electrons stored in the
floating gate to tunnel out. After erasure, the threshold voltage drops. A memory cell is read like
an EPROM cell, by driving the gate to the high level and detecting the drain current, which
depends on the threshold voltage. Erasing must be done carefully, because if a memory cell is
overerased, its threshold voltage may become negative, causing the cell to operate incorrectly.
Section 20.4.6 shows an optimal erase control flowchart and sample program.
Table 20.1 Principle of Memory Cell Operation
Memory
cell
Memory
array
(60-kbyte Dual-Power-Supply Flash Memory Version)
Flash Memory Overview
Flash Memory Operating Principle
Program
Vd
Vg = V
PP
0 V
Vd
Section 20 ROM
V
0 V
0 V
PP
Erase
Vs = V
PP
Open
Open
Open
0 V
V
0 V
PP
Read
Vd
Vg
0 V
Vd
V
0 V
0 V
437
CC