LV5809MX Datasheet, PDF (4/5 Pages) Sanyo Semicon Device – Step-down Switching Regulator

LV5809MX
Pin Function
Pin No. Pin name
Function
1 BOOT
Upper MOS transistor boot strap capacitance connection pin.
Connect the boot capacitance of about 0.022µF between SW
pins.
To protect the SW pin’s absolute maximum rating, to ensure
stable operation, and to eliminate noise, the boot capacitance
serial resistance (about 100Ω) Rb proves effective.
2
VIN
Input voltage pin.
Connect substantially large (10µF 2 parallel or more)
capacitance between this pin and GND.
3 SW
Power switch pin.
Connect the output LC filter. Connect the above capacitance
between this pin and BOOT pin.
4 GND
Ground pin.
5 FB
Feedback pin.
Sets the output voltage by means of split resistor in the section
of the output voltage VOUT - FB - GND. VOUT setting is made
as calculated below:
VOUT
=
Vref
×
{
1
+
(R1
+ R10)
R3
}
Vref = 0.8V
Example: 3.3V output voltage
(See Block Diagram and Sample Application Circuit)
VOUT
=
Vref
×
{
1
+
(27k + 4.3k)
10k
}
8 SS
=3.304V
Soft start pin.
Sets the soft start time by means of the built-in 10µA source
voltage and external soft start capacity. The soft start capacity
C6 can be set as follows:
C6
=
10µA
×
Tss
Vref
Where, Tss is the soft start time and Vref is the reference
voltage.
Example: 1.2ms soft start time achieved
C6
=
10µA
×
1.2ms
0.8V
=
0.015µF
6 COMP
Phase compensation pin.
Connects with the phase compensation external capacitance
and resistance of DC/DC converter close loop.
Equivalent circuit
VIN
Short protection
circuit
BOOT
Output MOS
SW
VIN
Internal regulation line
10µA
SS
FB
VREF
0.8V
VIN
Internal regulation line
Short protection
circuit
COMP
7 EN
Enable pin.
Converter enabled when set to the HIGH voltage and disabled
when LOW voltage or OPEN state.
VIN
EN
5µA
1kΩ
183kΩ
2pF
Q117
183kΩ
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