SP6655ER-L Datasheet, PDF (13/16 Pages) Sipex Corporation – High Efficiency 400mA Synchronous Buck Regulator

APPLICATION INFORMATION
INDUCTORS SURFACE MOUNT
Inductor Specification
Inductance
(µH)
Manufacturer/Part No.
10
Murata LQH32CN100K11
10
TDK RLF5018T-100MR94
10
Coilcraft LPO6013-103K
22
Murata LQH32CN220K21
22
TDK RLF5018T- 220MR63
22
Coilcraft LPO6013-103
Series R Ω I_SAT (A)
Size
LxW(mm) Ht. (mm)
Inductor Type
Manufacturer
Website
0.300
0.45 3.2 x 1.6
1.8 Unshielded Ferrite Core murata.com
0.056
0.94 5.6 x 5.2
2.0 Shielded Ferrite Core tdk.com
0.300
0.70 6.0 x 5.4
1.3 Unshielded Ferrite Core coilcraft.com
0.710
0.25 3.2 x 1.6
1.8 Unshielded Ferrite Core murata.com
0.130
0.63 5.6 x 5.2
2.0 Shielded Ferrite Core tdk.com
0.520
0.45 6.0 x 5.4
1.3 Unshielded Ferrite Core coilcraft.com
CAPACITORS - SURFACE MOUNT
Capacitor Specification
Capacitance Manufacturer/Part No.
(µF)
ESR RippleCurrent
Size
Ω (max) (A) @ 45°C LxW(mm) Ht. (mm)
10
TDK C2012X5R0J106M
0.003
1.00
2.0 x 1.2 1.25
10
Murata GRM21BR60J106KE01 0.003
1.00
2.0 x 1.2 1.25
4.7 TDK C2012X5R0J475M
0.005
1.00
2.0 x 1.2 1.25
4.7 Murata GRM21BR60J475KE01 0.005
1.00
2.0 x 1.2 1.25
Voltage
(V)
6.3
6.3
6.3
6.3
Capacitor Type
Manufacturer
Website
X5R Ceramic tdk.com
POSCAP
murata.com
X5R Ceramic tdk.com
POSCAP
murata.com
Note: Components highlighted in bold are those used on the SP6655 Evaluation Board.
Table 2 Component Selection
Output Voltage Program
The output voltage is programmed by the external
divider, as shown in the typical application circuit
on page 1. First pick a value for R_I that is no larger
than 300K. Too large a value of R_I will reduce the
AC voltage seen by the loop comparator since the
internal FB pin capacitance can form a low pass
filter with R_F in parallel with R_I. The formula for
R_F with a given R_I and output voltage is:
R_F = ( ^VOUT - 1 ) • R_I
0.8V
Output Voltage Ripple Frequency
An important consideration in a power supply
application is the frequency value of the output
ripple. Given the control technique of the SP6655
(as described in the operations section), the
frequency of the output ripple will vary when in
light to moderate load in the discontinuous or
PFM mode. For moderate to heavy loads greater
than about 100mA inductor current ripple, (for
the typical 10µH inductor application on 100mA
is half the 200mA inductor current ripple), the
output ripple frequency will be fairly constant.
From the operations section, this maximum loop
frequency in continuous conduction mode is:
F_LP ≈
1 _* V_{OUT * (VIN - VOUT)}
K_ON
V_IN
Data for loop frequency, as measured from
output voltage ripple frequency, can be found in
the typical performance curves.
Layout Considerations
Proper layout of the power and control circuits is
necessary in a switching power supply to obtain
good output regulation with stability and a mini-
mum of output noise. The SP6655 application
circuit can be made very small and reside close to
the IC for best performance and solution size, as
long as some layout techniques are taken into
consideration. To avoid excessive interference
between the SP6655 high frequency converter and
the other active components on the board, some
Date: 09/27/05
SP6655 High Efficiency 400mA Synchronous Buck Regulator
13
© Copyright 2004 Sipex Corporation