LT3022EDHC#PBF Linear Technology, LT3022EDHC#PBF Datasheet - Page 15

• Manufacturer Part Number: LT3022EDHC#PBF
• Description: IC REG LDO ADJ 1A 16DFN
• Manufacturer: Linear Technology

Specifications of LT3022EDHC#PBF

• Regulator Topology: Positive Adjustable
• Voltage - Output: 0.2 ~ 9.5 V
• Voltage - Input: 0.9 ~ 10 V
• Voltage - Dropout (typical): 0.145V @ 1A
• Number Of Regulators: 1
• Current - Output: 1A
• Current - Limit (min): 1.1A
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-WFDFN, Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS INFORMATION
Calculating Junction Temperature
Example: Given an output voltage of 1.5V, an input voltage
range of 1.7V to 1.9V, an output load current range of 1mA
to 1A and a maximum ambient temperature of 85°C, what
is the maximum junction temperature for an application
using the DHC package?
The power dissipated by the device equals:
where:
so:
The thermal resistance is about 38°C/W depending on
the copper area. So the junction temperature rise above
ambient is approximately equal to:
The maximum junction temperature equals the maximum
junction temperature rise above ambient plus the maximum
ambient temperature or:
Protection Features
The LT3022 incorporates several protection features
that make it ideal for use in battery-powered circuits. In
addition to the normal protection features associated with
monolithic regulators, such as current limiting and thermal
limiting, the device also protects against reverse-input
voltages, reverse-output voltages and reverse output-to-
input voltages.
Current limit protection and thermal overload protection
protect the device against current overload conditions at its
output. For normal operation, do not exceed 125°C junction
temperature. The typical thermal shutdown temperature
is 165°C and the thermal shutdown circuit incorporates
about 7°C of hysteresis.
I
I
V
I
P = 1A • (1.9V – 1.5V) + 18mA • (1.9V) = 0.434W
0.434W • (38°C/W) = 16.5°C
T
LOAD(MAX)
LOAD(MAX)
GND
JMAX
IN(MAX)
at (I
= 85°C + 16.5°C = 101.5°C
= 1.9V
LOAD
• (V
= 1A
= 1A, V
IN(MAX
) – V
IN
= 1.9V) = 18mA
OUT
) + I
GND
• (V
IN(MAX)
)
The IN pins withstand reverse voltages of 10V. The LT3022
limits current fl ow to less than 1μA and no negative voltage
appears at OUT . The device protects both itself and the
load against batteries that are plugged in backwards.
The LT3022 incurs no damage if OUT is pulled below
ground. If IN is left open-circuited or grounded, OUT can
be pulled below ground by 10V. No current fl ows from
the pass transistor connected to OUT. However, current
fl ows in (but is limited by) the resistor divider that sets the
output voltage. Current fl ows from the bottom resistor in
the divider and from the ADJ pin’s internal clamp through
the top resistor in the divider to the external circuitry pulling
OUT below ground. If IN is powered by a voltage source,
OUT sources current equal to its current limit capability
and the LT3022 protects itself by thermal limiting. In this
case, grounding SHDN turns off the LT3022 and stops
OUT from sourcing current.
The LT3022 incurs no damage if the ADJ pin is pulled
above or below ground by 10V. If IN is left open-circuited
or grounded and ADJ is pulled above ground, ADJ acts
like a 25k resistor in series with two diodes. ADJ acts like
a 25k resistor if pulled below ground. If IN is powered by a
voltage source and ADJ is pulled below its reference voltage,
the LT3022 attempts to source its current limit capability
at OUT. The output voltage increases to V
with V
supports. This condition can potentially damage external
circuitry powered by the LT3022 if the output voltage
increases to an unregulated high voltage. If IN is powered
by a voltage source and ADJ is pulled above its reference
voltage, two situations can occur. If ADJ is pulled slightly
above its reference voltage, the LT3022 turns off the pass
transistor, no output current is sourced and the output
voltage decreases to either the voltage at ADJ or less. If
ADJ is pulled above its no-load recovery threshold, the
no-load recovery circuitry turns on and attempts to sink
current. OUT is actively pulled low and the output voltage
clamps at a Schottky diode above ground. Please note that
the behavior described above applies to the LT3022 only. If
a resistor divider is connected under the same conditions,
there will be additional V/R current.
DROPOUT
LT3022-1.5/LT3022-1.8
set by whatever load current the LT3022
LT3022/LT3022-1.2
IN
– V
DROPOUT
15
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