AAT1230 Datasheet, PDF (13/21 Pages) Advanced Analogic Technologies – 18V 100mA Step-Up Converter

Minimum 6.3V rated ceramic capacitors are required
at the input. Ceramic capacitors sized as small as
0603 are available which meet these requirements.
The AAT1230 provides excellent load transient
response, but large capacitance tantalum or solid-
electrolytic capacitors may be desired. These can
replace (or be used in parallel with) ceramic capaci-
tors. Both tantalum and OSCON-type capacitors are
suitable due to their low ESR and excellent tempera-
ture stability (although they exhibit much higher ESR
than MLC capacitors). Aluminum-electrolytic types
are less suitable due to their high ESR characteristics
and temperature drift. Unlike MLC capacitors, these
types are polarized and proper orientation on input
and output pins is required. 30% to 70% voltage der-
ating is recommended for tantalum capacitors.
Setting the Output Voltage
The output voltage may be programmed through a
resistor divider network located from the output to
FB1 and FB2 pins to ground. Pulling the SEL pin
high activates the FB1 pin which maintains a 1.2V
reference voltage, while the FB2 reference is dis-
abled. Pulling the SEL pin low activates the FB2
pin which maintains a 0.6V reference, while the
FB1 reference is disabled.
The AAT1230 output voltage can be programmed
by one of three methods. First, the output voltage
can be static by pulling the SEL logic pin either high
or low. Second, the output voltage can be dynam-
ically adjusted between two pre-set levels within a
2X operating range by toggling the SEL logic pin.
Third, the output can be dynamically adjusted to
any of 16 preset levels within a 2X operating range
using the integrated S²Cwire single wire interface
via the EN/SET pin.
Option 1: Static Output Voltage
A static output voltage can be configured by pulling
the SEL either high or low. SEL pin high activates the
FB1 reference pin to 1.2V (nominal). Alternatively,
the SEL pin is pulled low to activate the FB2 refer-
ence at 0.6V (nominal). Table 1 provides details of
resistor values for common output voltages from 10V
to 18V for SEL = High and SEL = Low options.
In the static configuration, the FB1 pin should be
directly connected to FB2. The resistor between
AAT1230
18V 100mA Step-Up Converter
FB1 and FB2 pins is not required. See Table 1 for
static output voltages with SEL = High or SEL =
Low. SEL = High corresponds to V_OUT(1) and SEL =
Low corresponds to V_OUT(2).
Option 2: Dynamic Voltage Control Using SEL Pin
The output may be dynamically adjusted between
two output voltages by toggling the SEL logic pin.
Output voltages V_OUT(1) and V_OUT(2) correspond to
the two output references, FB1 and FB2. Pulling
the SEL logic pin high activates V_OUT(1), while
pulling the SEL logic pin low activates V_OUT(2).
The minimum output voltage must be greater than
the specified maximum input voltage plus margin to
maintain proper operation of the AAT1230 boost
converter. In addition, the ratio of output voltages
V_OUT(2)/V_OUT(1) is always less than 2.0, correspon-
ding to a 2X (maximum) programmable range.
See Table 1 for dynamic output voltage settings
when toggling between SEL = High and SEL = Low.
SEL = High corresponds to V_OUT(1) and SEL = Low
corresponds to V_OUT(2).
V_OUT(1)
V_OUT(2)
R3 = 4.99kΩ
(SEL = High) (SEL = Low) R1 (kΩ) R2 (kΩ)
10.0V
–
36.5
–
12.0V
–
44.2
–
15.0V
–
57.6
–
16.0V
–
61.9
–
18.0V
–
69.8
–
–
10.0V
78.7
–
–
12.0V
95.3
–
–
15.0V
121
–
–
16.0V
127
–
–
18.0V
143
–
12.0V
10.0V
75
3.32
15.0V
10.0V
76.8
1.65
16.0V
10.0V
76.8
1.24
18.0V
10.0V
78.7
0.562
15.0V
12.0V
90.9
3.65
16.0V
12.0V
93.1
2.49
18.0V
12.0V
93.1
1.65
18.0V
15.0V
115
3.32
Table 1: SEL Pin Voltage Control Resistor
Values (1% resistor tolerance).
1230.2006.03.1.0
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