en5335 Enpirion, en5335 Datasheet - Page 7

• Manufacturer Part Number: en5335
• Description: 3a Voltage Mode Synchronous Buck Pwm Dc-dc Converter With Integrated Inductor 3-pin Programmable Output
• Manufacturer: Enpirion

Rev 1.0 November 2006
Theory of Operation
Synchronous Buck Converter
The
programmable power supply with integrated
power
inductor. The nominal input voltage range is 2.4-
5.0V. 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 3A of output current can be drawn from this
converter.
enables the use of small-size output capacitors.
The power supply has the following protection
features:
Additional features include:
Output Voltage Programming
The EN5335QI output voltage is programmed
using a 3-pin voltage-ID or VID selector.
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 choose VOUT.
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 2006 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.
EN5335QI
MOSFET
The
circuit,
5MHz
is
switches
a
limiting
operating
synchronous,
and
the
integrated
frequency
in-rush
Three
pin
Table 1: Output Voltage Select Table
Input Capacitor Selection
The EN5335QI requires between 10uF and 20uF
of input capacitance. Low-cost, low-ESR ceramic
capacitors should be used as input capacitors for
this converter. The dielectric must be X5R or
X7R rated. In some applications, lower value
capacitors are needed in parallel with the larger,
capacitors in order to provide high frequency
decoupling. It is recommended to use 10V rated
1210 MLCC capacitors.
Table 2. Recommended input capacitors.
Output Capacitor Selection
The EN5335QI has been optimized for use with
approximately 47µF of output capacitance. Low
ESR ceramic capacitors are required with X5R or
X7R rated dielectric formulation.
equivalent dielectric formulations must not be
used as these loose capacitance with frequency,
temperature and bias voltage.
Output ripple voltage is determined by the
aggregate output capacitor impedance. Output
7
Description
22uF, 10V,
47uF, 10V,
X7R, 1210
X5R, 1210
VS2*
0
0
0
0
1
1
1
1
VS1*
Murata
Taiyo Yuden
Murata
Taiyo Yuden
0
0
1
1
0
0
1
1
MFG
VS0*
0
1
0
1
0
1
0
1
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GRM32ER71A226KE20L
GRM32ER71A476KE20L
LMK325BJ226KM-T
LMK325BJ476KM-T
Output Voltage
Reserved
P/N
1.25V
3.3V
2.5V
1.8V
1.5V
1.2V
0.8V
EN5335QI
Y5V or