EP5368QI Datasheet, PDF (9/12 Pages) Enpirion, Inc. – 600mA Synchronous Buck Regulator With Integrated Inductor

April 2008
External Voltage Divider
As described above, the external voltage
divider option is chosen by connecting the
VS0, VS1, and VS2 pins to VIN or logic “high”.
The EP5368QI uses a separate feedback pin,
V_FB, when using the external divider. VSENSE
must be connected to V_OUT as indicated in
Figure 4.
V_IN
4.7uF
0603
ENABLE
V_in
V_Sense
V_out
EP5368QI ^Ra
VS0
VFB
VS1
Rb
VS2
GND
V_OUT
22µF
0805
Figure 4. External Divider application circuit.
The output voltage is selected by the following
formula:
( ) V_OUT
= 0.603V
1+
Ra
Rb
R_a must be chosen as 200KΩ to maintain loop
gain. Then R_b is given as:
R = 1.206x105 Ω
b _{VOUT − 0.603}
V_OUT can be programmed over the range of
0.603V to V_IN-0.4V.
Dynamically Adjustable Output
The EP5368QI is designed to allow for
dynamic switching between the predefined VID
voltage levels The inter-voltage slew rate is
optimized to prevent excess undershoot or
overshoot as the output voltage levels
transition. The slew rate is identical to the soft-
start slew rate of 1.5V/mS.
Dynamic transitioning between internal VID
settings and the external divider is not allowed.
EP5368QI
Input and Output Capacitors
The input capacitance requirement is 4.7uF
0603 MLCC. The input capacitor must be a
X5R/X7R MLCC. Y5V or equivalent dielectric
formulations lose capacitance with frequency,
bias, and with temperature, and are not
suitable for switch-mode DC-DC converter
input filter applications.
The output capacitance requirement is
approximately 20uF. Enpirion recommends a
single 22uF 0805 MLCC. Ripple performance
can be improved by using 2 x 10uF 0805 MLC
capacitors.
The output capacitor must be a X5R/X7R or
equivalent MLCC. Y5V or equivalent dielectric
formulations lose capacitance with frequency,
bias, and temperature and are not suitable for
switch-mode DC-DC converter output filter
applications.
Please consult Enpirion Applications Support
for other capacitor case size combinations.
Operation at 700mA Output Current
Operation at 700mA is supported by using the
application circuit shown in Figure 5. The
modification in the compensation is to ensure
stability over the entire set of input and output
voltage conditions.
V_IN
4.7uF
0603
ENABLE
V_in
V_Sense
V_out
EP5368QI ^Ra
VS0
V_FB
VS1
Rb
VS2
GND
V_OUT
C_a
22µF
0805
Figure 5. Applications circuit for operation at 700mA.
©Enpirion 2008 all rights reserved, E&OE
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