Datasheet

HG
SW/CSH
CSL
ILIM
FPWM
SNS
FREQ/SYNC
BOOST
VLIN5
SGND
COMP/SD
FB
TRACK
LG
PGND
LM3495
14
13
12
11
10
8 9
15
16
1
2
3
4
5
7
6
VIN
LM3495
SNVS410F –FEBRUARY 2006–REVISED APRIL 2013 www.ti.com
Connection Diagram
Figure 1. 16-Lead Plastic TSSOP Package (Top View)
See Package Number PW0016A
θ
JA
= 155°C/W
PIN DESCRIPTIONS
BOOST (Pin 1): Supply rail for the high-side FET gate drive. The voltage should be at least one gate threshold above the regulator input
voltage to properly turn on the high-side FET.
HG (Pin 2): Gate drive for the high-side N-channel FET. This signal is interlocked with LG to avoid shoot-through.
SW/CSH (Pin 3): Return path for the high-side FET driver and top Kelvin sense point for the load current. Connect this pin as close as
possible to the drain of the low-side FET with a separate trace. Also used along with CSL for zero crossing detection.
CSL (Pin 4): Bottom sense point for the load current. Connect this as close as possible to the source of the low-side FET with a separate
trace.
ILIM (Pin 5): Current limit threshold setting. This pin sources a fixed 20 µA current. A resistor of appropriate value should be connected
between this pin and the drain of the low-side FET.
FPWM (Pin 6): Control mode select. An open circuit at this pin allows the IC to operate in skip mode at light loads. A logic low or
connection to ground forces PWM operation at all times. This pin should not be pulled up to any voltage above 3.0V.
SNS (Pin 7): Output voltage sense pin. Connect this pin as close as possible to the positive terminal of the output capacitor with a separate
trace. This pin connects to an internal FET that discharges the output capacitor during shutdown.
FREQ/SYNC (Pin 8): Switching frequency select pin and input for external clock. Connect a resistor from this pin to ground to determine
switching frequency. Alternatively, a logic level clock signal between 200 kHz and 1.5 MHz can be applied to this pin through a 100 pF DC
blocking capacitor to set the switching frequency.
TRACK (Pin 9): Tracking pin. To force the output of the LM3495 to track another power supply, connect a resistor divider (smaller than 10
kΩ for better precision) from the output of the other supply directly to this pin. When not used, this pin should be connected directly to the
VLIN5 pin.
FB (Pin 10): Feedback pin. Connecting a resistor divider from the output voltage to this pin sets the DC level of the output voltage.
COMP/SD (Pin 11): Output of the error amplifier. The voltage level on this pin is compared with an internally generated ramp signal to
determine the duty cycle. This pin is necessary for compensating the control loop. This pin must be left floating for the converter to regulate
the output voltage in steady state. Forcing this pin below 0.3V shuts down the regulator.
SGND (Pin 12): Signal ground. Ground connection for the low power analog circuitry. Connect this pin to the PGND pin with a separate
trace.
VIN (Pin 13): Input voltage. Input to an internal 4.7V linear regulator. Bypass this pin with a minimum 1 µF ceramic capacitor.
VLIN5 (Pin 14): Output of the internal 4.7V linear regulator. Provides power to the high-side bootstrap and low-side driver. Bypass this pin
with a 2.2 µF ceramic capacitor to PGND.
LG (Pin 15): Gate drive for the low-side N-channel FET. This signal is interlocked with HG to avoid shoot-through.
PGND (Pin 16): Ground connection for the power circuitry. Connect to the source of the low-side FET and the output capacitor with heavy
traces or a copper plane.
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Product Folder Links: LM3495