ISL78213 Datasheet, PDF (14/15 Pages) Intersil Corporation – 3A Low Quiescent Current, High Efficiency Synchronous Buck Regulator

ISL78213
where high load transient or low output ripple is required.
It is recommended to check the system level
performance along with the simulation model.
TABLE 1. OUTPUT CAPACITOR VALUE vs V_OUT
V_OUT
(V)
C_OUT
(µF)
L
(µH)
0.8
2 x 22
1.0~2.2
1.2
2 x 22
1.0~2.2
1.5
2 x 22
1.5~3.3
1.8
2 x 22
1.5~3.3
2.5
2 x 22
1.5~3.3
3.3
2 x 22
2.2~4.7
3.6
2 x 22
2.2~4.7
Output Voltage Selection
The output voltage of the regulator can be programmed
via an external resistor divider that is used to scale the
output voltage relative to the internal reference voltage
and feed it back to the inverting input of the error
amplifier. Refer to Figure 1.
The output voltage programming resistor, R₃, will depend
on the value chosen for the feedback resistor and the
desired output voltage of the regulator. The value for the
feedback resistor is typically between 10kΩ and 100kΩ,
as shown in Equation 2.
R₃
=
------R----²-----^â‹---0---.--8---V--------
V_OUT – 0.8V
(EQ. 2)
If the output voltage desired is 0.8V, then R₃ is left
unpopulated and R₂ is shorted. There is a leakage
current from VIN to LX. It is recommended to preload the
output with 10µA minimum. For better performance, add
47pF in parallel with R₂ (100kΩ).
Input Capacitor Selection
The main functions for the input capacitor are to provide
decoupling of the parasitic inductance and to provide
filtering function to prevent the switching current flowing
back to the battery rail. Two 22µF X5R or X7R ceramic
capacitors are a good starting point for the input
capacitor selection.
Revision History
The revision history provided is for informational purposes only and is believed to be accurate, but not warranted. Please go to
web to make sure you have the latest Rev.
DATE
REVISION
CHANGE
3/11/10
FN7550.1 On Page 5, under PG, corrected typo for MAX limit from 0.2 to 2.0.
3/8/10
FN7550.0 Initial release.
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14
FN7550.1
March 16, 2010