88PG8226A1-NFE1C000 Marvell, 88PG8226A1-NFE1C000 Datasheet - Page 27

• Manufacturer Part Number: 88PG8226A1-NFE1C000
• Manufacturer: Marvell

V
V
V
VSET
PSET
OUT
V
IN
Copyright © 2008 Marvell
April 23, 2008, 2.00
Figure 11: Startup Sequence
Table 14: Output Voltage Option Steps
The 88PG82XX provides an innovative technique to set the output voltage. During start-up it reads
the value of external resistors, which are located outside the regulator’s feedback loop to program
the output voltage. By placing the output voltage programming resistor outside the regulator’s
feedback loop, its tolerance does not affect the accuracy of the output voltage. Normally, adjustable
regulators use 1% resistors to set the output voltage. However, these resistors are located inside the
feedback loop, introducing as much as 2% of initial accuracy error to the output voltage, resulting in
an overall initial accuracy of 3%. Whereas, the 88PG82XX initial accuracy is 2% for any of the eight
output voltages.
The VSET and PSET pins are sensitive to excessive leakage currents and stray capacitance. The
output voltage can potentially be programmed to the lower output voltage if there is contamination,
which introduces excessive leakage current on the VSET and PSET pin, especially for a RVSET and
RPSET of 470kΩ. The parasitic resistance on these nodes must be greater than 3 MΩ and the stray
capacitance must be less than 25 pF; otherwise, a 3.3V output can potentially end up at 3V.
Ste p
1
2
3
4
5
6
7
8
9
2.0 ms/DIV
V O U T (V )
0
3.3
3.0
2.5
1.8
1.5
1.2
1.0
0.8
Document Classification: Proprietary Information
RV S ET (K )
0
475
280
165
97.6
53.6
31.6
18.7
11
2V/DIV
1V/DIV
1V/DIV
1V/DIV
V
V
VSET
PSET
Figure 12: VSET = 2.5V and PSET =
Step
1
2
3
4
5
6
7
8
9
P S ET (% )
0
+10
+7.5
+5.0
+2.5
-2.5
-5.0
-7.5
-10
-5%
200
μ
s/DIV
Functional Description
Doc. No. MV-S103563-00 Rev. C
Output Voltage Settings
R S PS E T (k )
0
475
280
165
97.6
53.6
31.6
18.7
11
Page 27
500mV/DIV
500mV/DIV