LTC1844-1.5 LINER [Linear Technology], LTC1844-1.5 Datasheet - Page 5

• Manufacturer Part Number: LTC1844-1.5
• Description: 150mA, Micropower, Low Noise, VLDO Linear Regulator
• Manufacturer: LINER [Linear Technology]

PI FU CTIO S
IN (Pin 1): Power for LTC1844 and Load. Power is supplied
to the device through the IN pin. The IN pin should be
locally bypassed to ground if the LTC1844 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 adviseable to include an input
bypass capacitor in battery-powered circuits. A capacitor
in the range of 0.1 F to 1 F is usually sufficient. The
LTC1844 is designed to withstand reverse voltages on the
IN pin with respect to both ground and the output pin. In
the case of a reversed input, which can happen if a battery
is plugged in backwards, the LTC1844 will act as if there
is a large resistor in series with its input with only a small
amount of current flow.
GND (Pin 2): Ground and Heat Sink. Solder to a ground
plane or large pad to maximize heat dissipation.
SHDN (Pin 3, Fixed and SD Devices): Shutdown, Active
Low. This pin is used to put the LTC1844 into shutdown.
The SHDN pin current is typically less than 10nA. The
SHDN pin cannot be left floating and must be tied to the
input pin if not used. If reverse-battery protection is
desired, the SHDN pin must be tied to the input pin through
a large value resistor (10k to 1M).
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ADJ (Pin 4, Adjustable Devices): Output Adjust. For the
adjustable versions of the LTC1844, this is the input to the
error amplifier. It has a typical bias current of 30nA flowing
into the pin. The ADJ pin reference voltage is 1.25V
referenced to ground. The output voltage range is 1.25V to
6V and is typically set by connecting ADJ to a resistor
divider from OUT to GND. See Figure 2.
BYP (Pin 4, Fixed/Pin 3, BYP Devices): Noise Bypass.
The BYP pin is used to augment the internal noise filter to
improve low noise performance. A small low leakage
bypass capacitor from this pin to ground will filter the input
of the error amplifier to lower the output voltage noise.
Any value may be used; larger values will result in lower
output noise, but will increase initial power-up time.
Shutdown exit delay time after a brief shutdown (<10ms)
will not be affected. If not used, this pin must be left
unconnected.
OUT (Pin 5): Voltage Regulated Output. The OUT pin
supplies power to the load. A minimum output capacitor of
1 F is required to ensure stability. Larger output capacitors
may be required for applications with large transient loads
to limit peak voltage transients. See the Applications
Information section for more information on output
capacitance.
LTC1844 Series
1844ia
5