CSP1027 Datasheet, PDF (57/64 Pages) Agere Systems – CSP1027 Voice Band Codec for Cellular Handset and Modem Applications

Data Sheet
December 1999
CSP1027 Voice Band Codec for
Cellular Handset and Modem Applications
11 Timing Characteristics and Requirements (continued)
11.2 Power-On Reset
The CSP1027 has a power-on reset circuit that automatically clears the device upon power-on. If the supply voltage
falls below VDD MIN^*, the device must be reset. Figure 40 on page 57 shows two separate events: an initial power-
on and a power-on following a drop in the power supply.
* See Table 11 on page 47.
VDD
RAMP
0V
VDD MIN
VDD MIN
0.5 V
t9
t9
t10
t10
VOH
PORB _VOL
Figure 40. Power-On Reset Timing Diagram
5-7619 (F)
Table 26. Timing Requirement for Power-On Reset
Abbreviated
Reference
t9
VDD Ramp
Parameter
Min
Max
Unit
—
1
ms
Table 27. Timing Characteristic for Power-On Reset
Abbreviated
Reference
t10
Parameter
PORB Pulse Width (low to change)
Min
Max
Unit
1.5
7
ms
Note: The device needs to be clocked for at least six CLK cycles during reset after power-on. Otherwise, high and unstable current may flow.
Lucent Technologies Inc.
57