SP6652 Datasheet, PDF (8/16 Pages) Sipex Corporation – 1A, High Efficiency, High Frequency Current Mode PWM Buck Regulator

VOUT
C3
10µF
R_FBH
R_FBL
APPLICATIONS INFORMATION
L1
4.7µH
Rz
4kΩ
1 _PGND
LX ¹⁰
2 _{SGND PVIN} 9
3 _FB
SVIN ⁸
4 _{COMP SYNC} 7
5 _SD
MODE ⁶
SP6652
Cc
10nF
R1
10Ω
C2
1µF
VIN
C1
10µF
Complete Application Circuit.
SD
VIN
SYNC
Component Selection
The SP6652 PWM buck regulator circuit
requires 3 capacitors: 10µF for the PVIN input,
1µF input bypass for the SVIN and 10µF
for the output are typically recommended.
For the input capacitor, a value even larger
than 10µF will help reduce input voltage
ripple for applications sensitive to ripple on
the battery voltage. See the Typical Per-
formance Characteristics section for wave-
forms on input and output ripple with 10µF
capacitors. All the capacitors should be
surface mount ceramic for low lead induc-
tance necessary at the 1.4MHz switching
frequency of the SP6652 and to obtain low
ESR. This also helps improve bypassing
on the input pin and ripple on the output.
Ceramic capacitors with X5R or X7R tem-
perature grade are recommended for most
applications. A selection of recommended
capacitors is included in Table 1. The 1µF
SVIN input capacitor should have a series
resistor of about 10Ω value connected
from the input to the SVIN pin to form an RC
low pass filter to remove high frequency
spikes present on the input switching pin
PVIN. This will keep the SP6652 internal
reference and other sensitive circuits noise
free and ensure better output regulation.
The GND returns for the PVIN capacitor and
the output capacitor should be connected
directly to the PGND pin, which should con-
nect to the thermal pad ground located un-
der the SP6652. The GND return for the
1µF SVIN capacitor should be connected to
the SGND pin, which should be connected
separately to the PGND pin to avoid adding
PGND noise to the SP6652 SGND pin. See
the Typical SP6652 Circuit Layout for de-
tails on the recommended layout.
Output Voltage Selection
To set the output voltage for the SP6652,
a pair of resistors, RF and RI are used as a
voltage divider between the output voltage
at the output capacitor and the FB pin and
GND, as shown in the typical application cir-
cuit. The recommended value for the RI re-
sistor is 100KΩ to 200KΩ to keep the quies-
cent current low, but not have the impedance
too high at the FB pin for good regulation.
Oct10-07 RevJ
SP6652 1A, High Efficiency, Current Mode PWM Buck Regulator

© 2007 Sipex Corporation