EN5396QI
Functional Description
The EN5396QI is
a
synchronous, pin
(Vout − 0.75V )* Rb1
0.75V
Ra1 =
programmable power supply with integrated
power MOSFET switches and integrated
inductor. The nominal input voltage range is
2.375-5.5V. The output voltage is programmed
using an external resistor divider network. The
feedback control loop is a type III voltage-mode
and the part uses a low-noise PWM topology.
Up to 9A of output current can be drawn from this
converter. The 5MHz operating frequency
enables the use of small-size output capacitors.
If over-voltage protection is desired, use the
following equation to set the resistor Ra2 for the
desired OVP trip-point:
(OVPtrip − 0.90V )* Rb2
Ra2 =
0.90V
By design, if both resistor dividers are the same,
the OV trip-point will be 20% above the nominal
output voltage.
The power supply has the following protection
features:
• Programmable over-current protection (to
protect the IC from excessive load current)
• Thermal shutdown with hysteresis.
• Over-voltage protection
• Under-voltage lockout circuit to disable the
converter output when the input voltage is
less than approximately 2.2V
VIN
VOUT
POK
VOUT
PVIN
Ra2 Ra1
2 x
47µF
XOV
XFB
2 x 47µF
AVIN
SS
Rb1
Rb2
CSS
PGND
AGND
Additional features include:
• Soft-start circuit, limiting the in-rush
current when the converter is powered up.
• Power good circuit indicating whether the
output voltage is within 90%-120% of the
programmed voltage.
Figure 4. VOUT and OVP resistor divider networks.
NOTE: if no OVP divider is present, there will be no over-
voltage protection and POK will remain “high” as long as
VOUT remains above 90% of the nominal VOUT setting.
Input Capacitor Selection
Programming Output Voltage and OVP
The EN5396QI requires approximately 100uF of
input capacitance. Low ESR ceramic capacitors
are required with X5R or X7R rated dielectric
The EN5396 output voltage is programmed using
a simple resistor divider network. Figure 4 shows
the resistor divider configuration.
formulation.
Y5V or equivalent dielectric
formulations must not be used as these lose
capacitance with frequency, temperature and
bias voltage.
The EN5396 output voltage and over voltage
thresholds are determined by the voltages
presented at the XFB and XOV pins respectively.
These voltages are set by way of resistor dividers
between VOUT and AGND with the midpoint going
to XFB and XOV.
In some applications, lower value capacitors are
needed in parallel with the larger, capacitors in
order to provide high frequency decoupling.
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:
©Enpirion 2009 all rights reserved, E&OE
9
www.enpirion.com
02393
11/12/2009
Rev:C
ENPIRION [ ENPIRION, INC. ]
