AS1326
Datasheet - Application Information
9 Application Information
Figure 19. Typical AS1326A Application Circuit
3.3µH
8
VIN = 2.4V
LX
10
+
33µF
ONN
6
9
VOUT = 3.3V
800mA
CLK/SEL
1
POUT
+
100µF
330nF
ISET
2
10Ω
AS1326A
5
REF
4
OUT
10nF
FB
3
GND
7
PGND
Setting the Output Voltages
For a fixed 3.3V output, connect pin FB to GND. To set adjustable output voltages between 2.5 and 5.0V, connect a
resistor voltage-divider to pin FB from pin OUT to GND (Figure 20).
Figure 20. Application Circuit using External Feedback Resistors
3.3µH
8
VIN = 2.4V
LX
10
+
33µF
ONN
6
9
VOUT
POUT
+
100µF
330nF
CLK/SEL
1
10Ω
AS1326A
5
ISET
2
OUT
REF
R1
R2
10nF
4
FB
3
GND
7
PGND
For the circuit shown in Figure 20, the input bias current into FB is <20nA, permitting large-value resistor-divider net-
works while maintaining accuracy. Place the resistor-divider network as close to the device as possible. Use a ≤ 270kΩ
resistor for R2, then calculate R1 as:
VOUT
VFB
⎛
⎝
⎞
– 1
--------------
R1 = R2 ⋅
(EQ 1)
⎠
Where:
VFB (the boost-regulator feedback set point) is 1.24V.
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