en5365 Enpirion, en5365 Datasheet - Page 9

• Manufacturer Part Number: en5365
• Description: 6a Voltage Mode Synchronous Buck Pwm Dc-dc Converter With Integrated Inductor 3-pin Vid Output Voltage Select
• Manufacturer: Enpirion

September 2007
Theory of Operation
Synchronous Buck Converter
The
programmable power supply with integrated
power
inductor. The nominal input voltage range is
2.375-5.5V. The output can be set to common
pre-set voltages by connecting appropriate
combinations of 3 voltage selection pins to
ground. The feedback control loop is a type III
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 has the following protection
features:
Additional features include:
Output Voltage Programming
The EN5365QI output voltage is programmed
using a 3-pin voltage-ID or VID selector. Three
binary VID pins allow the user to choose one of
seven pre-set voltages. Refer to table 1 for the
proper VID pin settings to program V
The voltage select pins, VS0, VS1, and VS2, are
pulled-up internally and so will default to a logic
high, or “1”, if left “open”. Connecting the voltage
select pin to ground will result in a logic “0”.
©Enpirion 2007 all rights reserved, E&OE
• Programmable over-current protection (to
• Thermal shutdown with hysteresis.
• Over-voltage protection
• Under-voltage lockout circuit to disable the
• Soft-start
• Power good circuit indicating whether the
protect the IC from excessive load current)
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.
EN5365QI
MOSFET
circuit,
is
switches
a
limiting
synchronous,
and
OUT
the
integrated
.
in-rush
pin
9
Table 1: Output Voltage Select Table
Input Capacitor Selection
The EN5365QI requires between 40-80uF of
input capacitance. Low ESR ceramic capacitors
are required with X5R or X7R dielectric
formulation.
formulations must not be used as these lose
capacitance with frequency, temperature and
bias voltage.
In some applications, lower value ceramic
capacitors maybe needed in parallel with the
larger capacitors in order to provide high
frequency decoupling.
Table 2. Recommended input capacitors.
Output Capacitor Selection
The EN5365QI has been optimized for use with
approximately 50µF of output capacitance. Low
ESR ceramic capacitors are required with X5R or
X7R dielectric formulation.
dielectric formulations must not be used as these
lose capacitance with frequency, temperature
and bias voltage.
Description
22uF, 10V,
47uF, 10V,
X5R, 1210
X5R, 1210
VS2*
0
0
0
0
1
1
1
1
VS1*
Y5V
Murata
Taiyo Yuden
Murata
Taiyo Yuden
0
0
1
1
0
0
1
1
MFG
or
VS0*
0
1
0
1
0
1
0
1
equivalent
GRM32ER71A226KE20L
GRM32ER71A476KE20L
www.enpirion.com
LMK325BJ226KM-T
LMK325BJ476KM-T
Y5V or equivalent
Output Voltage
Reserved
P/N
1.25V
3.3V
2.5V
1.8V
1.5V
1.2V
0.8V
EN5365QI
dielectric