SP6681 Datasheet, PDF (8/10 Pages) Sipex Corporation – High Efficiency Boost Charge Pump Regulator

MANUFACTURER / TELEPHONE #
PART NUMBER
CAPACITANCE / MAX ESR CAPACITOR
VOLTAGE
@ 100kHz SIZE / TYPE
TDK / 847-803-6100
C2012X5R1A225K
2.2µF / 10V
0.030Ω
0805 / X5R
TDK / 847-803-6100
C3216X5R1C475K
4.7µF / 10V
0.020Ω
1206 / X5R
AVX / 843-448-9411
1206ZC225K
2.2µF / 10V
0.030Ω
1206 / X7R
Taiyo Yuden / 847-925-0888
LMK212BJ225MG
2.2µF / 10V
0.030Ω
0805 / X5R
Taiyo Yuden / 847-925-0888
LMK316BJ475ML
4.7µF / 10V
0.020Ω
1206 / X7R
Table 2. Suggested Low ESR Cermic Surface Mount Capacitors.
The SP6681 circuit shown in figure 5 acts as a
3.3V in to 5V out for biasing the two 5V Logic
Level N-channel MOSFETs used in a step-
down DC/DC converter. The high current
switching path is from the +3.3V bus through
the N-channel MOSFETs and inductor L1 to the
output capacitors. To fully enhance Logic-
Level N-channel MOSFETs, +5V is needed
from the SP6681 output to the SP6120 VCC pin,
which supplies the low-side MOSFET MN1
with a 0V to 5V gate pulse through the GL pin.
For the top-side MOSFET MN2 (which has a
floating gate driver biased at the BST pin), the
boost pin BST is charge pumped up from the 0
to 3.3V switching at the switch node pin SWN,
with an additional 5V from SP6681 output,
through the DBST diode to a total of 8.3V when
the SWN is at 3.3V, or a total of 5V from gate to
source to fully enhance the MOSFET MN2. For
a more detailed schematic of a step-down DC/
DC converter, see the SP6120 datasheet.
3.3V
V_IN
4.7µF
+5V_OUT
2.2µF
2.2µF
1 _VOUT
2 _CF1P
3 _VIN
SP6681
CF2P ¹⁰
CF1N ⁹
GND ⁸
2.2µF
4 _CD4
CF2N ⁷
5 _Cx8
CLK ⁶
130kHz Internal Clock
DBST
VCC SP6120 BST
GH
VFB
SWN
PGND
GL
C_IN
CBST
MN2
L1
MN1
1.9V
1A to 7A
VOUT
RF
C_OUT
RI
Figure 5. SP6681 Circuit as a 3.3V to 5.0V Boost for 5V N-Channel MOSFETs in Buck DC/DC Converter Circuit.
Rev:A Date: 11/20/03
SP6681 High Efficiency Boost Charge Pump Regulator
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© Copyright 2002 Sipex Corporation