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Posts, Probes, and Jumpers
11
SNVU542 – July 2017
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Copyright © 2017, Texas Instruments Incorporated
LMS36x5x-Q1 EVM User's Guide
5
Posts, Probes, and Jumpers
5.1
VIN1 and GND1 Posts
The VIN1 and GND1 posts are standard input posts for connecting a power supply. The maximum input
voltage is 36 V with 42-V absolute maximum transient.
5.2
VOUT and GND Posts
The VOUT and GND posts are standard output posts for loading the EVM. Use sufficient lab cables and
preferably twisted wires to reduce inductive parasitic of lab cables. The typical output voltage is 5 V or 3.3
V.
5.3
IN+ and IN– Posts
Use IN+ and IN- for EMI measurements. When using IN+ and IN– posts, the IC is operated with an input
EMI filter. By default there is a 2-stage filter assembled with a wire wound Inductor PI-Filter for low
frequency filtering followed by a ferrite bead for high-frequency filtering. If one wishes to measure a setup
with a common-mode choke, add the choke by removing bypass resistors R1 and R2.
5.4
EN and GND2 Probe
EN and GND2 probe can be used to measure the enable voltage or drive it from external source. If an
external source is used, make sure to remove jumper J2. By default J2 jumper connects EN to VIN.
5.5
VINS, VOUTS, and GNDS Probe
VINS and VOUTS are sense points for input and output voltage.
NOTE:
Do not use for power supply or load.
These probe points are intended for use as kelvin sense points for static measurements including
efficiency, line regulation, and load regulation. For dynamic measurements please measure directly over
the input capacitors Cin1, Cin2, Cin3, and Cin4, and directly over the output capacitors Co1, Co2, Co3,
and Co4.
5.6
BIAS and GNDS Probe
The BIAS probe senses the bias voltage to the IC. Bias voltage is provided from the output voltage of the
IC over Rbias = 3-
Ω
resistor. An external bias supply voltage can be provided by removing Rbias to
disconnect IC output voltage as the source for bias.
5.7
RESET and GND3 Probe
RESET provides an accurate Power Good signal with release delay. By default jumper J3 is set to VOUT
and pulls the RESET pin to VOUT through a 100-k
Ω
resistor. Since RESET is an open-drain output, it can
also be pulled to other external voltage levels by removing jumper J3.
5.8
SYNC and GND3 Probe
By default the IC is running with internal oscillator at 400 kHz. Over the SYNC pin, an external function
generator can be connected to take control of the LMS3635 and LMS3655’s clock, changing the switching
frequency. SYNC function can be used for custom frequency modulation techniques. Spread spectrum will
always be disabled when a SYNC signal is present.
