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14

Skip M ode (SMOD#)

The Skip Mode function allow s for higher converter

efficiency w hen operated in light-load conditions. When

SMOD# is pulled LOW, the low -side MOSFET gate

signal is disabled (held LOW), preventing discharge of

the output capacitors as the filter inductor current

attempts reverse current flow

– know n as “Diode

Emulation” Mode.

When the SMOD# pin is pulled HIGH, the synchronous

buck converter w orks in Synchronous Mode. This mode

allow s for gating on the Low Side MOSFET. When the

SMOD# pin is pulled LOW, the low -side MOSFET is

gated off. If the SMOD# pin is connected to the PWM

controller, the controller can actively enable or disable

SMOD# w hen the controller detects light-load condition

from output current sens ing. Nor mally this pin is active

LOW. See Figure 28 for timing delays.

Table 2.

SMOD# Logic

DISB#

PWM

SMOD#

GH

GL

0

X

X

0

0

1

3-State

X

0

0

1

0

0

0

0

1

1

0

1

0

1

0

1

0

1

1

1

1

1

0

Note:

4.

The SMOD# feature is intended to have a short propagation delay betw een the SMOD# signal and the low -side

Figure 28.

SMOD# Tim ing Diagram

PWM

VSWH

GH

to

VSWH

GL

90%

10%

90%

1.0V

2.2V

Delay from SMOD#going

HS turn-on with SMOD# LOW

SMOD#

Delay from SMOD#going

DCM

CCM

CCM

10%

10%

10%