Datasheet

Board Configuration www.ti.com
6. Slowly vary the input voltages from 6V and 18.5V. Both output voltages should remain in regulation
with a nominal value of 3.3V on VO1 and 1.2V on VO2.
Figure 1. Basic Test Setup for LM3000EVAL Board
3 Board Configuration
3.1 External Clock Synchronization
A SYNC terminal has been provided in this evaluation board in order to synchronize the converter to an
external clock or other fixed frequency signal from 200 kHz to 1.5 MHz. Refer to LM3000 datasheet for
complete information.
Figure 2. Synchronization at 3.3V Output
3.2 CLKOUT
A CLKOUT terminal provides an external clock signal 90 degrees out of phase with the main clock. This
clock signal can be used to synchronize a second LM3000.
3.3 Tracking
LM3000 evaluation board is configured such that VOUT2 tracks VOUT1, while VOUT1 voltage increases
with a rate determined by the value of C17 which is the soft-start capacitor for VOUT1 (Condition 1). This
configuration will not allow VOUT2 to be turned on independently without turning on VOUT1. In order to
track VOUT1, TRK2 pin should be connected to a divider junction between R14 and R15 through R26.
When both outputs are used to track an external source (Condition 2), then R25, R26, and R28 should be
left open and a 10Ω resistor should be added into R24 and R27.
2
AN-1951 LM3000 Evaluation Board SNVA389A–July 2009–Revised May 2013
Submit Documentation Feedback
Copyright © 2009–2013, Texas Instruments Incorporated