SIP1759DB VISHAY [Vishay Siliconix], SIP1759DB Datasheet - Page 5

• Manufacturer Part Number: SIP1759DB
• Description: Buck-Boost Regulator
• Manufacturer: VISHAY [Vishay Siliconix]

DESIGNS CONSIDERATIONS
Setting the Adjustable Output Voltage
The SiP1759 regulated output can be adjusted from 2.5 V to
5.5 V via resistor divider network from V
Typical Application Circuits). R1 and R2 should be kept in the
50 kΩ to 100 kΩ range for low power consumption, while
maintaining adequate noise immunity. The value R1 is
calculated using the following formula:
R1 = R2 {(V
V
Capacitor Selection
Capacitor selection for C
in the voltage output ripple, output current and overall
physical size of the circuit.
TYPICAL CHARACTERISTICS
Document Number: 72949
S09-1453-Rev. D, 03-Aug-09
FB
is nominally 1.235 V.
120
100
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
80
60
40
20
OUT
0
1.5
0.5
/V
1.0
(V
FB
2.0
OUT
) - 1}
1.5
Efficiency vs. Input Voltage
< V
2.5
IN
Start-Up Input Voltage
IN
2.0
, C
) R
OUT
LOAD
3.0
Input Voltage (V)
Input Voltage (V)
2.5
and C
= 33 Ω
3.5
3.0
I
OUT
3.5
X
4.0
will have an impact
I
OUT
OUT
at 10 mA
4.0
I
at 50 mA
4.5
OUT
to GND (see
4.5
at 100 mA
5.0
5.0
5.5
5.5
Ceramic capacitors are recommenced for their low ESR
(≤ 20 mΩ) which will help keep the output voltage ripple at a
minimum. The initial values for the C
should be 10 µF, the C
Output Voltage Ripple
The SiP1759 automatically decides whether to be in step up
mode or step down mode depending on the V
current load conditions, therefore the voltage output ripple
will vary. In step-up mode the voltage output ripple is higher
than step-down mode. But unless V
than V
from buck mode to boost mode as necessary to charge the
transfer capacitor and the ripple will increase. Reducing the
C
frequency and a reduction of the output ripple.
X
capacitor value will cause an increase in the switching
1.00E-01
1.00E-02
1.00E-03
1.00E-04
1.00E-05
1.00E-06
1.00E-07
OUT
0.20
0.16
0.12
0.08
0.04
0.00
(V
Quiescent Current vs. Input Voltage (No Load)
1.5
IN
0.5
≥ V
Output voltage Ripple vs. Input Voltage
2.0
OUT
1.5
X
2.5
+ 1 V) , in heavy load the IC will slip
capacitor should be 0.33 µF.
50 mA
10 mA
3.0
Input Voltage (V)
Input Voltage (V)
2.5
3.5
Vishay Siliconix
IN
IN
and C
3.5
4.0
is significant larger
SiP1759
www.vishay.com
OUT
4.5
100 mA
IN
, V
4.5
capacitors
5.0
OUT
and
5.5
5.5
5