MC68HC912BL16 Datasheet, PDF (47/128 Pages) Freescale Semiconductor, Inc – 16-Bit Microcontroller

13.5 V
12.6 V
11.4 V
6.5 V
4.5 V
4.15 V
Freescale Semiconductor, Inc.
30 ns MAXIMUM
t_er
VFPE ENVELOPE
VDD ENVELOPE
COMBINED VDD AND VFPE
0V
– 0.30 V
POWER
ON
NORMAL
READ
PROGRAM
ERASE
VERIFY
POWER
DOWN
Figure 9 V_FPE Operation Range
Use of an external circuit to condition VFPE is recommended. Figure 19 shows a simple circuit that
maintains required voltages and filters transients. VFPE is pulled up to VDD via Schottky diode D2.
Application of programming voltage via diode D1 reverse-biases D2, protecting VDD from
excessive reverse current. D2 also protects the FLASH from damage should programming voltage
go to zero. Programming power supply voltage must be adjusted to compensate for the forward-
bias drop across D1. The charge time constant of R1 and C1 filters transients, while R2 provides a
discharge bleed path for C1. Allow for RC charge and discharge time constants when applying and
removing power. When using this circuit, keep leakage from external devices connected to the
VFPE pin low, to minimize diode voltage drop.
MC68HC912BL16TS/D
For More Information On This Product,
47
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