SS8051T11TB SSC [Silicon Standard Corp.], SS8051T11TB Datasheet - Page 6

• Manufacturer Part Number: SS8051T11TB
• Description: Micro-Power Step-up DC/DC Converter
• Manufacturer: SSC [Silicon Standard Corp.]

Rev.2.01 6/06/2003
BLOCK DIAGRAM
APPLICATIONS INFORMATION
The SS8051 is a boost converter with an integrated
N-channel MOSFET (refer to the block diagram above).
The boost cycle is initiated when the FB pin voltage drops
below 1.2V and the MOSFET turns on. During the period
that the MOSFET is on, the inductor current ramps up
until the 350mA current limit is reached. Then the
MOSFET turns off and the inductor current flows through
the external schottky diode, ramping down to zero.
During the MOSFET off period, the inductor current
charges the output capacitor and the output voltage
climbs. This pumping mechanism continues cycle by
cycle until the FB pin voltage exceeds 1.2V and the
non-switching mode starts. In this mode, the SS8051
consumes as little as 20uA typically, saving on battery
power.
Choosing an Inductor
There are several recommended inductors that work
well with the SS8051 in Table 1. Use the equations
and recommendations in the next few sections to find
the proper inductance value for your design.
V
V
IN
IN
V O U T
V O U T
R 1
R 1
R 2
R 2
C 1
C 1
F B
F B
1.2 V
1.2 V
B I A S
B I A S
+
+
V R E F
V R E F
E R R O R
E R R O R
C O M P
C O M P
V C C
V C C
S H U T D O W N
S H U T D O W N
e n _ s w
e n _ s w
L O G I C
L O G I C
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S H D N
S H D N
O C
O C
C O M P
C O M P
+
+
P U M P C O N T R O L
P U M P C O N T R O L
T
T
C O N T R O L
C O N T R O L
O F F
O F F
L 1
L 1
P U L S E
P U L S E
CDRH4D18-4R7
D R I V E R
D R I V E R
CDRH4D18-100
DO1608-472
DO1608-103
DO1608-223
Inductor Selection – Boost Regulator
The appropriate inductance value for the boost regulator
application may be calculated from the following
equation. Select a standard inductor close to this value.
LQH3C4R7
LQH3C100
LQH3C220
CD43-4R7
CD43-100
PART
G N D
G N D
T
ABLE
L =
S W
S W
1. R
VALUE? µ H)
V
OUT
ECOMMENDED
4.7
4.7
4.7
4.7
10
22
10
10
10
22
-V
I
IN(MIN)
LIM
MAX DCR ? W )
+V
I
0.26
0.30
0.92
0.11
0.18
0.16
0.20
0.09
0.16
0.37
C 2
C 2
NDUCTORS
D
x t
OFF
V
V
O U T
O U T
SS8051
www.murata.com
www.sumida.com
www.coilcraft.com
VENDOR
Sumida
Coilcraft
Murata
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