LTC2190I View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
LTC2190I Datasheet PDF : 28 Pages
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LTC2192
LTC2191/LTC2190
APPLICATIONS INFORMATION
Reference
The LTC2192/LTC2191/LTC2190 have an internal 1.25V
voltage reference. For a 2V input range using the internal
reference, connect SENSE to VDD. For a 1V input range
using the internal reference, connect SENSE to ground.
For a 2V input range with an external reference, apply a
1.25V reference voltage to SENSE (Figure 9).
The input range can be adjusted by applying a voltage to
SENSE that is between 0.625V and 1.30V. The input range
will then be 1.6 • VSENSE.
The VREF, REFH and REFL pins should be bypassed as
shown in Figure 8. A low inductance 2.2µF interdigitated
capacitor is recommended for the bypass between REFH
and REFL. This type of capacitor is available at a low cost
from multiple suppliers.
Alternatively, C1 can be replaced by a standard 2.2µF
capacitor between REFH and REFL. The capacitors should
be as close to the pins as possible (not on the back side
of the circuit board).
Figure 8c and 8d show the recommended circuit board
layout for the REFH/REFL bypass capacitors. Note that in
Figure 8c, every pin of the interdigitated capacitor (C1)
is connected since the pins are not internally connected
in some vendors’ capacitors. In Figure 8d the REFH and
REFL pins are connected by short jumpers in an internal
layer. To minimize the inductance of these jumpers they
can be placed in a small hole in the GND plane on the
second board layer.
C3
0.1µF
C1
2.2µF
REFH LTC2192
REFL
REFH
C2
0.1µF
REFL
CAPACITORS ARE 0402 PACKAGE SIZE
219210 F08b
Figure 8b. Alternative REFH/REFL Bypass Circuit
1.25V
LTC2192
VREF
2.2µF
5Ω
1.25V BANDGAP
REFERENCE
0.625V
TIE TO VDD FOR 2V RANGE;
TIE TO GND FOR 1V RANGE;
RANGE = 1.6 • VSENSE FOR
0.625V < VSENSE < 1.300V
SENSE
C2
0.1µF
C3
0.1µF
–+
+–
C1
–+
+–
REFH
REFL
REFH
REFL
C1: 2.2µF LOW INDUCTANCE
INTERDIGITATED CAPACITOR
TDK CLLE1AX7S0G225M
MURATA LLA219C70G225M
AVX W2L14Z225M
OR EQUIVALENT
RANGE
DETECT
AND
CONTROL
BUFFER
INTERNAL ADC
HIGH REFERENCE
0.8x
DIFF AMP
INTERNAL ADC
LOW REFERENCE
219210 F08a
Figure 8a. Reference Circuit
219210 F08c
Figure 8c. Recommended Layout for the REFH/REFL Bypass
Circuit in Figure 8a
219210 F08d
Figure 8d. Recommended Layout for the REFH/REFL Bypass
Circuit in Figure 8b
1.25V
EXTERNAL
REFERENCE
VREF
2.2µF
SENSE
1µF
LTC2192
219210 F09
Figure 9. Using an External 1.25V Reference
219210p
19
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