Texas Instruments LMP8646 Evaluation Board LMP8646EB/NOPB LMP8646EB/NOPB Ficha De Dados
Códigos do produto
LMP8646EB/NOPB
LMP8646EB User’s Guide
November 2011
Page 8 of 20
SNOU010
3.
Quick Start: Resistive Load Application
Now, let’s look at the design process for a resistive load application as seen in Figure 4. To see the
current limiting capability of the LMP8646, the open-loop current must be greater than the close-loop
current. An open-loop occurs when the LMP8646 output is not connected the LM3102’s feedback pin.
For this example, we will let the open-loop current to be 1.5A and the close-loop current, I
current limiting capability of the LMP8646, the open-loop current must be greater than the close-loop
current. An open-loop occurs when the LMP8646 output is not connected the LM3102’s feedback pin.
For this example, we will let the open-loop current to be 1.5A and the close-loop current, I
LIMIT
, to be 1A.
I
SENSE
-
RON
RON
CIN
CSS
VIN
LM3102
CBST
LOUT
COUT
V+ = 6V
VFB
0.8V
Rg
Cg
VOUT
RFB3
RFB1
RFB2
CV+
10 uF
5V
I+
I-
RSENSE
VO_3102
LMP8646
RLOAD
Figure 4 – Schematic for the Resistive Load Application
1. Design Parameters:
a. VIN_3102 = 8V to 42V, typical 18V
b. Vout_3102 = 3V
c. Rsense = 55 mOhm
d. Load resistance = 2 Ohm
b. Vout_3102 = 3V
c. Rsense = 55 mOhm
d. Load resistance = 2 Ohm
2. Step 1: Choose Components for the LM3102
Refer to the LM3102 evaluation board app note (AN-1646) located at
http://www.ti.com/lit/snva248
to
choose the appropriate components for the LM3102. For this application, we recommend increasing
the input capacitance to 67 uF.
For this example, the following LM3102 components are recommended:
the input capacitance to 67 uF.
For this example, the following LM3102 components are recommended: