ltc3025-2 Linear Technology Corporation, ltc3025-2 Datasheet - Page 7

• Manufacturer Part Number: ltc3025-2
• Description: 500ma Micropower Vldo Linear Regulators Features
• Manufacturer: Linear Technology Corporation

pin FuncTions
BIAS (Pin 1): BIAS Input Voltage. BIAS provides internal
power for LTC3025-X circuitry. The BIAS pin should be
locally bypassed to ground if the LTC3025-X is more than a
few inches away from another source of bulk capacitance.
In general, the output impedance of a battery rises with
frequency, so it is usually advisable to include an input
bypass capacitor in battery-powered circuits. A capacitor
in the range of 0.01µF to 0.1µF is usually sufficient.
GND (Pin 2): Ground. Connect to a ground plane.
IN (Pin 3): Input Supply Voltage. The output load current
is supplied directly from IN. The IN pin should be locally
bypassed to ground if the LTC3025-X is more than a few
inches away from another source of bulk capacitance. In
general, the output impedance of a battery rises with fre-
quency, so it is usually advisable to include an input bypass
capacitor when supplying IN from a battery. A capacitor
in the range of 0.1µF to 1µF is usually sufficient.
OUT (Pin 4): Regulated Output Voltage. The OUT pin
supplies power to the load. A minimum ceramic output
capacitor of at least 1µF is required to ensure stability.
Larger output capacitors may be required for applications
with large transient loads to limit peak voltage transients.
block DiagraM
1
6
2
BIAS
SHDN
GND
SHDN
REFERENCE
0.4V
SOFT-START
LTC3025-1
–
+
6µA
OUT
ADJ
IN
3
4
5
See the Applications Information section for more informa-
tion on output capacitance.
ADJ (Pin 5) LTC3025-1: Adjust Input. This is the input to
the error amplifier. The ADJ pin reference voltage is 0.4V
referenced to ground. The output voltage range is 0.4V to
3.6V and is typically set by connecting ADJ to a resistor
divider from OUT to GND. See Figure 2.
SENSE (Pin 5) LTC3025-2, LTC3025-3, LTC3025-4: Out-
put Sense. The sense is the input to the resistor divider
driving the error amplifier. Optimum regulation will be
obtained at the point where SENSE is connected to OUT.
The SENSE pin bias current is 10µA at the nominal rated
output voltage.
SHDN (Pin 6): Shutdown Input, Active Low. This pin is
used to put the LTC3025-X into shutdown. The SHDN pin
current is typically less than 10nA. The SHDN pin cannot
be left floating and must be tied to a valid logic level (such
as BIAS) if not used.
GND (Exposed Pad Pin 7): Ground and Heat Sink. Must
be soldered to PCB ground plane or large pad for optimal
thermal performance.
1
6
2
BIAS
SHDN
GND
SHDN
REFERENCE
LTC3025-1/LTC3025-2/
LTC3025-3/LTC3025-4
0.4V
LTC3025-2, LTC3025-3, LTC3025-4
SOFT-START
R1
40k
+
–
6µA
R2
80k (LTC3025-2)
110k (LTC3025-3)
140k (LTC3025-4)
SENSE
OUT
30251234 BD
IN
3
4
5
30251234fe