Datasheet

LT3042
4
3042fb
For more information www.linear.com/LT3042
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Quiescent Current in
Shutdown (V
EN/UV
= 0V)
V
IN
= 6V
l
0.3 1
10
µA
µA
Internal Current Limit
(Note 12)
V
IN
= 2V, V
OUT
= 0V
V
IN
= 12V, V
OUT
= 0V
V
IN
= 20V, V
OUT
= 0V
l
l
220
130
270
300
180
320
250
mA
mA
mA
Programmable
Current Limit
Programming Scale Factor: 2V< V
IN
< 20V (Note 11)
V
IN
= 2V, V
OUT
= 0V, R
ILIM
= 625Ω
V
IN
= 2V, V
OUT
= 0V, R
ILIM
= 2.5kΩ
l
l
180
45
125
200
50
220
55
mA • kΩ
mA
mA
PGFB Trip Point
PGFB Trip Point Rising
l
291 300 309 mV
PGFB Hysteresis PGFB Trip Point Hysteresis 7 mV
PGFB Pin Current V
IN
= 2V, V
PGFB
= 300mV 25 nA
PG Output Low Voltage I
PG
= 100µA
l
30 100 mV
PG Leakage Current V
PG
= 20V
l
1 µA
Reverse Input Current V
IN
= –20V, V
EN/UV
= 0V, V
OUT
= 0V, V
SET
= 0V
l
50 µA
Reverse Output Current V
IN
= 0, V
OUT
= 5V, SET = Open 2 5 µA
Minimum Load Required
(Note 13)
V
OUT
< 1V
l
10 µA
Thermal Shutdown T
J
Rising
Hysteresis
162
8
°C
°C
Start-Up Time V
OUT(NOM)
= 5V, I
LOAD
= 200mA, C
SET
= 0.47µF, V
IN
= 6V, V
PGFB
= 6V
V
OUT(NOM)
= 5V, I
LOAD
= 200mA, C
SET
= 4.7µF, V
IN
= 6V, V
PGFB
= 6V
V
OUT(NOM)
= 5V, I
LOAD
= 200mA, C
SET
= 4.7µF, V
IN
= 6V, R
PG1
= 50kΩ,
R
PG2
= 700kΩ (with Fast Start-Up to 90% of V
OUT
)
55
550
10
ms
ms
ms
Thermal Regulation 10ms Pulse –0.01 %/W
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The EN/UV pin threshold must be met to ensure device operation.
Note 3: Maximum junction temperature limits operating conditions. The
regulated output voltage specification does not apply for all possible
combinations of input voltage and output current, especially due to the
internal current limit foldback which starts to decrease current limit at
V
IN
– V
OUT
> 12V. If operating at maximum output current, limit the input
voltage range. If operating at the maximum input voltage, limit the output
current range.
Note 4: OUTS ties directly to OUT.
Note 5: Dropout voltage is the minimum input-to-output differential
voltage needed to maintain regulation at a specified output current. The
dropout voltage is measured when output is 1% out of regulation. This
definition results in a higher dropout voltage compared to hard dropout —
which is measured when V
IN
= V
OUT(NOMINAL)
. For lower output voltages,
below 1.5V, dropout voltage is limited by the minimum input voltage
specification. Linear Technology is unable to guarantee maximum
dropout voltage specifications at high currents due to production test
limitations with Kelvin-sensing the package pins. Please consult the
Typical Performance Characteristics for curves of dropout voltage as a
function of output load current and temperature measured in a typical
application circuit.
Note 6: GND pin current is tested with V
IN
= V
OUT(NOMINAL)
and a current
source load. Therefore, the device is tested while operating in dropout.
This is the worst-case GND pin current. GND pin current decreases at
higher input voltages. Note that GND pin current does not include SET pin
or ILIM pin current but Quiescent current does include them.
Note 7: SET and OUTS pins are clamped using diodes and two 25Ω series
resistors. For less than 5ms transients, this clamp circuitry can carry
more than the rated current. Refer to Applications Information for more
information.
Note 8: Adding a capacitor across the SET pin resistor decreases output
voltage noise. Adding this capacitor bypasses the SET pin resistor’s
thermal noise as well as the reference current’s noise. The output noise
then equals the error amplifier noise. Use of a SET pin bypass capacitor
also increases start-up time.
Note 9: The LT3042 is tested and specified under pulsed load conditions
such that T
J
≈ T
A
. The LT3042E is 100% tested at 25°C and performance
is guaranteed from 0°C to 125°C. Specifications over the –40°C to 125°C
operating temperature range are assured by design, characterization, and
correlation with statistical process controls. The LT3042I is guaranteed
over the full –40°C to 125°C operating temperature range. The LT3042MP
is 100% tested and guaranteed over the full –55°C to 150°C operating
temperature range. The LT3042H is 100% tested at the 150°C operating
junction temperature. High junction temperatures degrade operating
lifetimes. Operating lifetime is derated at junction temperatures greater
than 125°C.
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