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| EY1501DI-ADJ Datasheet, PDF (10/13 Pages) Altera Corporation – EY1501DI-ADJ High Performance 1A LDO | |||
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Page 10
Phase Boost Capacitor
A small phase boost capacitor, Cpb, can be placed across the top resistor, R2, in the feedback resistor divider network in
order to place a zero at:
Fz = 2----Ï---x----R---1-2---x---C---P----B-
(EQ. 4)
This zero increases the crossover frequency of the LDO and provides additional phase resulting in faster load transient
response.
It is important to note that LDO stability and load transient performance are affected by the type of output capacitor
used. For optimal result, empirical tuning of CPB is suggested for each specific application. It is recommended to not
use CPB when high ESR capacitors such as Aluminum Electrolytic or Tantalum are used on the output.
Table 2 shows the recommended minimum ceramic COUT and corresponding CPB, R2 and R1 for different output
voltages.
TABLE 2. RECOMMENDED CPB FOR DIFFERENT VOUT AND COUT
VOUT
R2
R1
COUT
CPB
(V)
(kΩ)
(kΩ)
(µF)
(pF)
5.0
2.61
0.287
10
100
3.3
2.61
0.464
10
100
2.5
2.61
0.649
10
82
1.8
2.61
1.0
10
82
1.5
2.61
1.3
10
68
1.5
2.61
1.3
22
150
1.2
2.61
1.87
22
120
1.2
2.61
1.87
47
270
1.0
2.61
2.61
47
220
0.8
2.61
4.32
47
220
INPUT CAPACITOR
For proper operation, a minimum capacitance of 10µF X5R/X7R is required at the input. This ceramic input capacitor
must be connected to the VIN and GND pins of the LDO with PCB traces no longer than 0.5cm.
Power Dissipation and Thermals
The junction temperature must not exceed the range specified in the âRecommended Operating Conditions (Notes 7,
8)â on page 4. The power dissipation can be calculated by using Equation 5:
PD = (VIN â VOUT) Ã IOUT + VIN Ã IGND
(EQ. 5)
The maximum allowable junction temperature, TJ(MAX) and the maximum expected ambient temperature, TA(MAX) determine
the maximum allowable power dissipation, as shown in Equation 6:
PD(MAX) = (TJ(MAX) â TA) â θJA
(EQ. 6)
θJA is the junction-to-ambient thermal resistance.
For safe operation, enure that the power dissipation PD, calculated from Equation 5, is less than the maximum
allowable power dissipation PD(MAX).
Enpirion Power Datasheet EY1501DI-ADJ High Performance 1A LDO
10039
May 28, 2014
May 2014 Altera Corporation
Rev A
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