AN1740 Freescale Semiconductor / Motorola, AN1740 Datasheet - Page 26

• Manufacturer Part Number: AN1740
• Description: Applications Using the Analog Subsystem on MC68HC05JJ/JP Series Microcontrollers
• Manufacturer: Freescale Semiconductor / Motorola

Application Note
Discharge Device
26
Also attached to PB0 is a MOS transistor designed to sink at least 1 mA
of current from a source of 0.4 volts into V
provide a discharge current at least 10 times the source current.
However, this device does not behave like a pure resistor as its current
sinking capability varies with both the supply voltage and the voltage
present on the PB0 pin.
The typical discharge current versus PB0 voltage and supply voltage is
shown in
resistance is about 250 , and for V
discharge resistance is about 190 .
Freescale Semiconductor, Inc.
110
100
90
80
70
60
50
40
30
20
10
For More Information On This Product,
0
0
Figure 10. Typical Current Source Behavior (PB0)
Figure
Go to: www.freescale.com
11. For V
1
MODE RANGE
MAX COMMON
DD
VOLTAGE ON PB0 – VOLTS
of 3 volts, the equivalent discharge
2
V
DD
= 3.0 V
DD
of 5 volts, the equivalent
SS
3
. The design goal was to
MODE RANGE
MAX COMMON
4
V
DD
= 5.0 V
T
MOTOROLA
A
= 25 C
AN1740
5