EN5337QI
excellent transient performance for most
applications. It is optimized for use with about
50μF of output filter capacitance at the voltage
sensing point. Additional load decoupling
capacitance may be placed beyond the voltage
sensing point outside the control loop. Voltage
mode operation provides high noise immunity
at light load, and low output impedance.
Input Under-Voltage Lock-Out
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 ensure high noise immunity and
prevent false UVLO triggers.
Compensation
In some applications modifications to the
compensation may be required. For more
information, contact Enpirion Applications
Engineering support.
The EN5337QI uses a type 3 compensation
network. A piece of the compensation circuit is
the phase lead capacitor CA in Figure 5. This
network will provide wide loop bandwidth and
Application Information
The EN5337QI output voltage is determined by
the voltage presented at the XFB pin. This
voltage is set by way of a resistor divider
between VOUT and AGND with the midpoint
going to XFB. A phase lead capacitor CA is
also required for stabilizing the loop. Figure 5
shows the required components and the
equations to calculate the values.
some applications, lower value capacitors are
needed in parallel with the larger, capacitors in
order to provide high frequency decoupling.
Recommended Input Capacitors
Description
MFG
Murata
P/N
10uF, 10V, 10%
GRM31CR71A106KA01L
X7R, 1206
(1-2 capacitors needed)
22uF, 10V, 20%
X5R, 1206
(1 capacitor needed)
Taiyo Yuden
Murata
LMK316B7106KL-T
GRM31CR61A226ME19L
LMK316BJ226ML-T
Taiyo Yuden
VOUT
Output Capacitor Selection
RA
RB
CA
The EN5337QI has been optimized for use
with approximately 50μF of output filter
capacitance at the voltage sensing point
Additional load decoupling capacitance may be
placed beyond the voltage sensing point
outside the control loop. Low ESR ceramic
capacitors are required with X5R or X7R rated
XFB
RA =150kΩ, CA = 22pF
0.75*RA
RB =
dielectric formulation.
Y5V or equivalent
(VOUT − 0.75V )
dielectric formulations must not be used as
these lose too much capacitance with
frequency, temperature and bias voltage.
Figure 5: VOUT Resistor Divider Network and
Compensation Capacitor CA
Input Capacitor Selection
Output ripple voltage is determined by the
aggregate output capacitor impedance. Output
impedance, denoted as Z, is comprised of
effective series resistance, ESR, and effective
series inductance, ESL:
The EN5337QI 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. Y5V or equivalent
dielectric formulations must not be used as
these lose too much capacitance with
frequency, temperature and bias voltage. In
Z = ESR + ESL
Placing output capacitors in parallel reduces
the impedance and will hence result in lower
©Enpirion 2009 all rights reserved, E&OE
9
www.enpirion.com
02638
6/18/2009
Rev:D
ENPIRION [ ENPIRION, INC. ]
