EN23F0QI Datasheet, PDF (17/26 Pages) Enpirion, Inc. – 15A Voltage Mode Synchronous Buck PWM

Thermal Overload Protection
Thermal shutdown circuit will disable device
operation when the junction temperature exceeds
approximately 150ºC. After a thermal shutdown
event, when the junction temperature drops by
approx 20ºC, the converter will re-start with a
normal soft-start.
Input Under-Voltage Lock-Out (UVLO)
Internal circuits ensure that the converter will not
start switching until the input voltage is above the
specified minimum voltage. Hysteresis, input de-
glitch and output leading edge blanking ensures
high noise immunity and prevents false UVLO
triggers.
Master / Slave (Parallel) Operation:
Up to four EN23F0QI devices may be connected in
a Master/Slave configuration to handle larger load
currents. The maximum output current for each
parallel device will need to be de-rated by 20
percent so that no devices will over current due to
current mis-match. The Master device’s switching
clock may be phase-locked to an external clock
source via the S_IN pin or left open and use its
default switching frequency. The device is placed in
Master mode by pulling the M/S pin low or in Slave
mode by pulling M/S pin high. Note that the M/S pin
is also pulled low for standalone mode. In Master
mode, the internal PWM signal is output on the
S_OUT pin. This PWM signal from the Master is
EN23F0QI
fed to the Slave device at its S_IN input. The Slave
device acts like an extension of the power FETs in
the Master. The inductor in the Slave prevents
crow-bar currents from Master to Slave due to
timing delays. Parallel operation in dual supply
mode is shown in Figure 9. Single supply mode
operation may also be implemented similarly. Note
that only critical components are shown. The red
text and red lines indicate the important parallel
operation connections and care should be taken in
layout to ensure low impedance between those
paths. The parallel current matching is illustrated in
Figure 8.
Parallel Current Share Breakdown
20
17.5
15
12.5
MASTER
SLAVE
IDEAL
10
7.5
5
2.5
0
0
CONDITIONS
EN23F0QI
V_IN = 12V
V_OUT = 1.2V
5
10
15
20
25
30
TOTAL OUTPUT CURRENT (A)
Figure 8. Parallel Current Matching
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Enpirion Confidential
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