EV1380QI Datasheet, PDF (12/18 Pages) Enpirion, Inc. – 8a synchronous highly integrated dc-dc

R_B = 240k.
Although the EV1380QI integrates most of the
compensation network, a phase lead capacitor
and a resistor are required in parallel with the
upper resistor R_a of the external feedback
network as shown in Figure 6. For the 1.5V
VDDQ example stated above, C_A = 120pF.
The compensation is optimized for use with
3x100μF or 4x100μF 1206, X5R ceramic
output capacitors.
In exceptional cases, modifications to the
compensation might be required. The
EV1380QI’s compensation can be modified for
specific applications. For more information,
contact Power Applications support.
R_A  40,000 VDDQ (value in )
C_A

8 10^6
R_A
(C_A /R_A in F/)
Round C_A down to closest
standard value lower than
calculated value.
R_B  4  R_A

V_FB is 0.6V
nominal

R₁  3 k
Figure 6: External Feedback and Compensation Network
Enable Operation
The ENABLE pin should be tied to VDDQ
through an 0201 resistor. With the device input
power applied, the device automatically starts
to operate with a soft-start, provided the AVIN
voltage is above the upper UVLO high
threshold of ~2.2 volts.
Input Capacitor Selection
The EV1380QI requires between 80uF and
100uF of input capacitance. Low ESR ceramic
capacitors are required with X5R or X7R
dielectric formulation. Y5V or equivalent
dielectric formulations must not be used
because these dielectrics lose capacitance
with frequency, temperature and bias voltage.
In some applications, lower value ceramic
EV1380 Datasheet
capacitors maybe needed in parallel with the
larger capacitors in order to provide high
frequency decoupling.
Recommended Input Capacitors
Description
47uF, 10V,
X5R, 1206
47uF, 4V,
X5R, 0805
100uF, 6.3V,
X5R, 1206
MFG
Taiyo
Yuden
Murata
Murata
P/N
LMK316BJ476ML-T
GRM21BR60G476M
GRM31CR60J107M
Output Capacitor Selection
The EV1380QI has been optimized for use with
an output capacitance of 300400µF. Low ESR
ceramic capacitors are required with X5R or
X7R dielectric formulation. Y5V or equivalent
dielectric formulations must not be used as
these lose capacitance with frequency,
temperature and bias voltage.
Recommended Output Capacitors
Description
47uF, 10V,
X5R, 1206
47uF, 6.3V,
X5R, 1206
100uF, 6.3V,
X5R, 1206
MFG
Taiyo
Yuden
Taiyo
Yuden
Murata
Murata
P/N
LMK316BJ476ML-T
JMK316BJ476ML-T
GRM31CR60J476ME19L
GRM31CR60J107M
Output ripple voltage is primarily determined by
the aggregate output capacitor impedance. At
the 1.5MHz switching frequency output
impedance, denoted as Z, is comprised mainly
of effective series resistance, ESR, and
effective series inductance, ESL:
Z = ESR + ESL.
Placing multiple capacitors in parallel reduces
the impedance and hence will result in lower
ripple voltage.
1 _ 1 _ 1 _{ ... } 1
Z_Total Z₁ Z ₂
Z_n
08888
12
March 18, 2015
www.altera.com/enpirion
Rev C