Datasheet

MC56F825x/MC56F824x Digital Signal Controller, Rev. 3
Specifications
Freescale Semiconductor56
7.8 Power-On Reset, Low Voltage Detection Specification
7.9 Voltage Regulator Specifications
The MC56F825x/MC56F824x has two on-chip regulators. One supplies the PLL, crystal oscillator, NanoEdge placement
PWM, and relaxation oscillator. It has no external pins and therefore has no external characteristics that must be guaranteed
(other than proper operation of the device). The second regulator supplies approximately 2.5 V to the
MC56F825x/MC56F824x’s core logic. For proper operation, this regulator requires an external capacitor of 2.2 µF or greater.
Ceramic and tantalum capacitors tend to provide better performance tolerances. The output voltage can be measured directly
on the V
CAP
pin. The specifications for this regulator appear in Table 26.
7.10 AC Electrical Characteristics
Tests are conducted using the input levels specified in Table 23. Unless otherwise specified, propagation delays are measured
from the 50% to the 50% point, and rise and fall times are measured between the 10% and 90% points, as shown in Figure 15.
Figure 15. Input Signal Measurement References
Table 25. Power-On Reset and Low-Voltage Detection Parameters
Characteristic Symbol
Min
Typ Max Unit
Low-Voltage Interrupt for 3.3 V supply
1
1
When V
DD
drops below LVI27, an interrupt is generated.
V
LVI27
2.6 2.7 2.8 V
Low-Voltage Interrupt for 2.5 V supply
2
2
When V
DD
drops below LVI21, an interrupt is generated.
V
LVI21
—2.18— V
Low-Voltage Interrupt Recovery Hysteresis V
EIH
—50—mV
Power-On Reset Threshold
3
3
While power is ramping up, this signal remains active for as long as the internal 2.5 V is below 2.18 V or
the 3.3 V V
DD
voltage is below 2.7 V, no matter how long the ramp-up rate is. The internally regulated
voltage is typically 100 mV less than V
DD
during ramp-up until 2.5 V is reached, at which time it self-reg-
ulates.
POR 2.6 2.7 2.8 V
Brown-Out Reset Threshold
4
4
Brown-Out Reset occurs whenever the internally regulated 2.5 V digital supply drops below 1.8 V.
BOR — 1.8 1.9 V
Table 26. Regulator Parameters
Characteristic Symbol Min Typical Max Unit
Short Circuit Current I
SS
— 900 1300 mA
Short Circuit Tolerance
(V
CAP
shorted to ground)
T
RSC
——30minutes
V
IH
V
IL
Fall Time
Midpoint1
Low High
90%
50%
10%
Rise Time
The midpoint is V
IL
+ (V
IH
– V
IL
)/2.
Input Signal