LX1742 データシートの表示（PDF） - Microsemi Corporation
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LX1742 Datasheet PDF : 13 Pages
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INTEGRATED PRODUCTS
LX1742
High Efficiency High Voltage Boost Controller
PRODUCTION DATA SHEET
EVALUATION BOARD
OVERVIEW
The LXE1742 evaluation board is available from
Microsemi for assessing overall circuit performance. The
evaluation board, shown in Figure 5, is 3 by 3 inches (i.e.,
7.6 X 7.6cm) square and factory calibrated to provide a
nominal 18V output from a 1.6V to 6.0V input. Circuit
designers can easily modify the output voltage and peak
current to suit their particular application by adjusting the
R2, R3, and R4 values accordingly. Further, other
components are easily swapped out to promote design
verification of any particular circuit application. Table 1
describes the evaluation board’s electrical interface.
ELECTRICAL CONNECTIONS
The system level DC input voltage is applied to VIN.
Connect the test load to VOUT. The Vin & GND terminal
at J4 provides easy test point access. A similar connection is
available for monitoring the output voltage via J5. The
output voltage is adjusted by selecting appropriate values for
R3 and R24. Further adjustment of the output voltage is
achieved by applying either a DC voltage or a PWM-type
signal to the ADJ input (J4).
The evaluation board accommodates both low frequency
(f < 100KHz) and high frequency (f > 100KHz) PWM
signals by connecting either JU1 or JU4 jumper position
respectively. The ADJ pin is easily grounded for fixed
voltage applications by inserting a jumper into the JU5
position. Table 2 provides a complete list of all jumper
positions.
Removing the jumper from the /SHDN position disables
the LX1742 by disconnecting pin 4 from VIN. The load is
still capable of drawing current through the inductor & diode
circuit path when the IC is in shutdown mode. Hence,
VOUT during shutdown will be approximately VIN minus
the inductor and diode forward voltage drop.
The LX1742 can achieve output voltages up to 25V. In
certain applications, it is necessary to protect the load from
excessive voltage excursions. The evaluation board
provides a zener clamp diode (D1) for this purpose.
The LXE1742 evaluation board offers a cost effective
solution for evaluation of the LX1742. Table 3 provides the
factory installed component list for the evaluation board and
the board schematic is shown in Figure 4.
Name
VIN
Vin (J4)
SHDN (J4)
ADJ (J4)
GND (J4)
GND
FDBK
GND2
VOUT
SWITCH
/SHDN
Application
Range
0 to 6V
0 to 6V
0 to VIN
0 to VIN-
100mV
0V
0V
0 to VIN
0V
VIN to 25V
N/A
0 to VIN
Table 1: Input and Output Pin Assignments
Description
Main power supply input for evaluation board
Connected to VIN (Alternate position or test point)
Pulled up to VCC on board (10KΩ), Ground to inhibit the LX1742.
Apply a DC input or PWM input to adjust the output voltage (note: see figure 9).
Circuit ground
Additional circuit ground connection point.
Apply a DC input or PWM input to adjust the output voltage.
Additional circuit ground connection point.
Output voltage test point. Programmed for 18V output, adjustable up to 25V.
Test point for lX1742 pin 1.
A DC voltage above (below) 1.6V (0.4V) enables (disables) the LX172
Note: All pins are referenced to ground.
Copyright © 2000
Rev. 1.0b, 2005-03-03
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 8
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