TMS570LS3137
SPNS162.–SEPTEMBER 2011
www.ti.com
4.3.2 Power-Down Sequence
The different supplies to the device can be powered down in any order.
4.3.3 Power-On Reset: nPORRST
This is the power-on reset. This reset must be asserted by an external circuitry whenever the I/O or core
supplies are outside the specified recommended range. This signal has a glitch filter on it. It also has an
internal pulldown.
4.3.3.1 nPORRST Electrical and Timing Requirements
Table 4-4. Electrical Requirements for nPORRST
NO Parameter
MIN
MAX
Unit
VCCPORL
VCC low supply level when nPORRST must be active during
power-up
0.5
V
VCCPORH
VCC high supply level when nPORRST must remain active during
power-up and become active during power down
1.14
V
V
V
VCCIOPORL
VCCIOPORH
VIL(PORRST)
VCCIO / VCCP low supply level when nPORRST must be active during
power-up
1.1
VCCIO / VCCP high supply level when nPORRST must remain active
during power-up and become active during power down
3.0
Low-level input voltage of nPORRST VCCIO > 2.5V
Low-level input voltage of nPORRST VCCIO < 2.5V
0.2 * VCCIO
0.5
V
V
3
tsu(PORRST)
Setup time, nPORRST active before VCCIO and VCCP > VCCIOPORL
0
ms
during power-up
6
7
th(PORRST)
tsu(PORRST)
Hold time, nPORRST active after VCC > VCCPORH
1
2
ms
Setup time, nPORRST active before VCC < VCCPORH during power
µs
down
8
9
th(PORRST)
th(PORRST)
tf(nPORRST)
Hold time, nPORRST active after VCCIO and VCCP > VCCIOPORH
Hold time, nPORRST active after VCC < VCCPORL
1
0
ms
ms
ns
500
2000
Filter time nPORRST pin;
pulses less than MIN will be filtered out, pulses greater than MAX
will generate a reset.
3.3 V
1.2 V
VCCIOPORH
VCCIOPORH
VCCIO / VCCP
8
6
VCCPORH
VCC
VCCPORH
7
6
VCCIOPORL
7
VCCIOPORL
VCCPORL
VCCPORL
VCC (1.2 V)
VCCIO / VCCP(3.3 V)
3
9
VIL
VIL
VIL
VIL(PORRST)
VIL(PORRST)
nPORRST
NOTE: There is no timing dependency between the ramp of the VCCIO and the VCC supply voltage; this is just an exemplary drawing.
Figure 4-1. nPORRST Timing Diagram
54
System Information and Electrical Specifications
Submit Documentation Feedback
focus.ti.com: TMS570LS3137
Copyright © 2011, Texas Instruments Incorporated