en5360 Enpirion, en5360 Datasheet - Page 7

• Manufacturer Part Number: en5360
• Description: 6a Voltage Mode Synchronous Buck Pwm Dc-dc Converter
• Manufacturer: Enpirion

Theory of Operation
Synchronous Buck Converter
The
programmable power supply with integrated
power MOSFET switches and inductor. The
nominal input voltage range is 2.5-5.0V. The
output can be set to common voltages by
connecting appropriate combinations of 3 voltage
selection pins to ground. If different voltage
levels are required, provision is also made to
allow external programming. The feedback
control loop is voltage-mode and the part uses a
low-noise PWM topology. Up to 6A of output
current can be drawn from this converter. The
5MHz operating frequency enables the use of
small-size output capacitors.
The power supply also has protection features
such as:
Additional features include:
Output Voltage Programming
The EN5360 output voltage is programmed using
one of two methods. Common output voltages
are achieved by tying one or more of the three
Voltage Select pins (VS0, VS1 & VS2) to ground
(see Table 1). If all three are left floating, the
output voltage and over voltage thresholds are
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• Programmable over-current protection (to
• Thermal
• Over-voltage protection that stops the
• Under-voltage lockout circuit to disable the
• Soft-start
• Power good circuit indicating whether the
protect the IC from excessive load current)
converter from getting too hot)
PWM switching and turns on the lower N-
MOSFET at 120% of the programmed
output voltage in order to protect the load
from an OV condition.
converter output when the input voltage is
less than approximately 2.2V
current when the converter is powered up.
output voltage is within 90%-120% of the
programmed voltage.
EN5360
shutdown
circuit,
is
a
limiting
synchronous,
(to
protect
the
in-rush
the
pin
7
determined by the voltages presented at the XFB
and XOV pins respectively. These voltages
should be set by way of resistor dividers between
V
and XOV (See Figure 1).
It is recommended that Rb1 and Rb2 resistor
values be ~2kΩ. Use the following equation to
set the resistor Ra1 for the desired output
voltage:
If over-voltage protection is desired, use the
following equation to set the resistor Ra2 for the
desired OVP trip-point:
By design, if both resistor dividers are the same,
the OV trip-point will be 20% above the nominal
output voltage.
Figure 1: External output voltage and OVP setting
Table 1: Output Voltage Select Table
*NOTE: The VS0, VS1 and VS2 pins are defaulted to a ‘1’
with an internal pull-up resistor. Only connect these pins to
AGND if a ‘0’ is required. If a ‘1’ is required, then leave the
pin floating.
Ra
Ra
22µF
OUT
1
2
VS2*
0
0
0
0
1
1
1
1
=
=
to AGND with the midpoint going to XFB
(
(
** 0.8V ref only, not guaranteed performance
Vout
OVPtrip
15 nF
−
0
VS1*
0
0
1
1
0
0
1
1
0
8 .
8 .
. 0
V
−
V
SS
AGND
PGND
PVIN
AVIN
96
. 0
* )
V
96
Rb
PGND
VOUT
V
XOV
XFB
VS0*
0
1
0
1
0
1
0
1
1
* )
Rb
2
Ra2
Rb2
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Output Voltage
3.3V
2.5V
1.8V
1.5V
1.25V
1.2V
0.8V**
User Selectable
AGND
Rb1
Ra1
V
47µF
OUT