LTC3109 Linear Technology, LTC3109 Datasheet - Page 6

• Manufacturer Part Number: LTC3109
• Description: Ultralow Voltage Step-Up Converter and Power Manager
• Manufacturer: Linear Technology

LTC3109
Typical perForMance characTerisTics
pin FuncTions
VSTORE (Pin 1/Pin 3): Output for the Storage Capacitor or
Battery. A large storage capacitor may be connected from
this pin to GND for powering the system in the event the
input voltage is lost. It will be charged up to the maximum
VAUX clamp voltage. If not used, this pin should be left
open or tied to VAUX.
VAUX (Pin 2/Pin 4): Output of the Internal Rectifier Cir-
cuit and V
capacitance to ground. An active shunt regulator clamps
VAUX to 5.25V (typical).
V
voltage at this pin is regulated to the voltage selected by
VS1 and VS2 (see Table 1). Connect this pin to a reservoir
capacitor or to a rechargeable battery. Any high current
pulse loads must be fed by the reservoir capacitor on
this pin.
V
Connect this pin to a switched load. This output is open
until V
through a 1Ω PMOS switch. If not used, this pin should
be left open or tied to V
V
will be enabled when this pin is driven high. There is an
internal 5M pull-down resistor on this pin. If not used,
this pin can be left open or grounded.
20mV/DIV

5mA/DIV
OUT
OUT2
OUT2_EN
V
I
LDO
LDO
(Pin 3/Pin 5): Main Output of the Converter. The
OUT_EN
(Pin 4/ Pin 6): Switched Output of the Converter.
0mA TO 3mA LOAD STEP
C
LDO Step Load Response
LDO
CC
(Pin 5/Pin 7): Enable Input for V
= 2.2µF
for the IC. Bypass VAUX with at least 1µF of
is driven high, then it is connected to V
200µs/DIV
OUT
.
(QFN/SSOP)
3109 G15
V
OUT2_EN
1V/DIV
1V/DIV
V
OUT2
CH2
CH1
OUT2
Enable Input and V
10mA LOAD ON V
C
OUT
. V
= 220µF
OUT2
OUT
OUT2
1ms/DIV
PGOOD (Pin 6/Pin 8): Power Good Output. When V
is within 7.5% of its programmed value, this pin will be
pulled up to the LDO voltage through a 1M resistor. If
V
go low. This pin can sink up to 100µA.
VLDO (Pin 7/Pin 9): Output of the 2.2V LDO. Connect a
2.2µF or larger ceramic capacitor from this pin to GND.
If not used, this pin should be tied to VAUX.
GND (Pins 8, 11, 16, Exposed Pad Pin 21/Pins 10, 13,
18): Ground Pins. Connect these pins directly to the ground
plane. The exposed pad serves as a ground connection and
as a means of conducting heat away from the die.
VS2 (Pin 20/Pin 2): V
pin to ground or VAUX to program the output voltage
(see Table 1).
VS1 (Pin 19/Pin 1): V
pin to ground or VAUX to program the output voltage
(see Table 1).
Table 1. Regulated Output Voltage Using Pins VS1 and VS2
OUT
OUT2
drops 9% below its programmed value PGOOD will
VAUX
VAUX
GND
GND
VS2
T
A
3109 G16
= 25°C, unless otherwise noted.
CH2, V
CH4, V
50mV/DIV
CH1, V
VSTORE
1V/DIV
1V/DIV
1V/DIV
CH3
OUT
LDO
OUT
OUT
IN
VAUX
VAUX
GND
GND
VS1
Running on Storage Capacitor
C
V
Select Pin 2. Connect this
Select Pin 1. Connect this
STORE
OUT
LOAD = 100µA
= 470µF
www.DataSheet4U.com
5SEC/DIV
2.35V
V
3.3V
4.1V
5.0V
OUT
OUT
3109f
3109 G17