ZY7120 Datasheet, PDF (19/34 Pages) Power-One – 20A DC-DC Intelligent POL Data Sheet 3V to 13.2V Input 0.5V to 5.5V Output

ZY7120 20A DC-DC Intelligent POL Data Sheet
3V to 13.2V Input • 0.5V to 5.5V Output
Figure 31. Transient Response with Optimal Voltage
Positioning
8.2 Sequencing and Tracking
Turn-on delay, turn-off delay, and rising and falling
output voltage slew rates can be programmed in the
GUI Sequencing/Tracking window shown in Figure
32 or directly via the I²C bus by writing into the DON,
DOF, and TC registers, respectively. The registers
are shown in Figure 33, Figure 34, and Figure 36.
Figure 32. Sequencing/Tracking Window
8.2.1 Turn-On Delay
Turn-on delay is defined as an interval from the
application of the Turn-On command until the output
voltage starts ramping up.
R/W-0
DON7
Bit 7
R/W-0
DON6
R/W-0
DON5
R/W-0
DON4
R/W-0
DON3
R/W-0
DON2
R/W-0
DON1
R/W-0
DON0
Bit 0
Bit 7:0 DON[7:0]: Turn-on delay time
00h: corresponds to 0ms delay after turn-on command has occurred
…
FFh: corresponds to 255ms delay after turn-on command has occurred
Figure 33. Turn-On Delay Register DON
8.2.2 Turn-Off Delay
U
---
Bit 7
U
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
---
DOF5 DOF4 DOF3 DOF2 DOF1 DOF0
Bit 0
Bit 7:6 Unimplemented, read as ‘0’
Bit 5:0 DOF[5:0]: Turn-off delay time
00h: corresponds to 0ms delay after turn-off command has occurred
…
3Fh: corresponds to 63ms delay after turn-off command has occurred
Figure 34. Turn-Off Delay Register DOF
Turn-off delay is defined as an interval from the
application of the Turn-Off command until the output
voltage reaches zero (if the falling slew rate is
programmed) or until both high side and low side
switches are turned off (if the slew rate is not
programmed). Therefore, for the slew rate controlled
turn-off the ramp-down time is included in the turn-off
delay as shown in Figure 35.
Turn-Off
Command
Internal
ramp-down
command
VOUT
User programmed turn-off delay, T_DF
Calculated
delay T_D Ramp-down time, TF
Falling slew
rate dV_F/dT
Time
Figure 35. Relationship between Turn-Off Delay and Falling
Slew Rate
As it can be seen from the figure, the internally
calculated delay T_D is determined by the equation
below.
T_D
= T_DF
− ^VOUT
dV_F
,
dT
For proper operation T_D shall be greater than zero.
The appropriate value of the turn-off delay needs to
be programmed to satisfy the condition.
REV. 2.1 MAR 14, 2007
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