LT3013MPFE Linear Technology, LT3013MPFE Datasheet - Page 12

• Manufacturer Part Number: LT3013MPFE
• Description: SP-LINREG, 80Vin, 250mA, LDO W/ PWRGD In TSSOP
• Manufacturer: Linear Technology

LT3013
APPLICATIONS INFORMATION
The LT3013 is a 250mA high voltage low dropout regula-
tor with micropower quiescent current and shutdown.
The device is capable of supplying 250mA at a dropout
voltage of 400mV. The low operating quiescent current
(65μA) drops to 1μA in shutdown. In addition to the
low quiescent current, the LT3013 incorporates several
protection features which make it ideal for use in bat-
tery-powered systems. The device is protected against
both reverse input and reverse output voltages. In battery
backup applications where the output can be held up by
a backup battery when the input is pulled to ground, the
LT3013 acts like it has a diode in series with its output
and prevents reverse current fl ow.
Adjustable Operation
The LT3013 has an output voltage range of 1.24V to 60V.
The output voltage is set by the ratio of two external
resistors as shown in Figure 1. The device servos the
output to maintain the voltage at the adjust pin at 1.24V
referenced to ground. The current in R1 is then equal to
1.24V/R1 and the current in R2 is the current in R1 plus
the ADJ pin bias current. The ADJ pin bias current, 30nA
at 25°C, fl ows through R2 into the ADJ pin. The output
voltage can be calculated using the formula in Figure 1. The
value of R1 should be less than 250k to minimize errors
in the output voltage caused by the ADJ pin bias current.
12
V
V
I
OUTPUT RANGE = 1.24V TO 60V
ADJ
OUT
ADJ
= 30nA AT 25°C
= 1.24V
= 1.24V
1 +
R2
R1
+ (I
ADJ
)(R2)
Figure 1. Adjustable Operation
V
IN
IN
Note that in shutdown the output is turned off and the
divider current will be zero.
The adjustable device is tested and specifi ed with the
ADJ pin tied to the OUT pin and a 5μA DC load (unless
otherwise specifi ed) for an output voltage of 1.24V. Speci-
fi cations for output voltages greater than 1.24V will be
proportional to the ratio of the desired output voltage to
1.24V; (V
output current change of 1mA to 250mA is –7mV typical at
V
Output Capacitance and Transient Response
The LT3013 is designed to be stable with a wide range of
output capacitors. The ESR of the output capacitor affects
stability, most notably with small capacitors. A minimum
output capacitor of 3.3μF with an ESR of 3Ω or less is
recommended to prevent oscillations. The LT3013 is a
micropower device and output transient response will be
a function of output capacitance. Larger values of output
capacitance decrease the peak deviations and provide
improved transient response for larger load current
changes. Bypass capacitors, used to decouple individual
components powered by the LT3013, will increase the
effective output capacitor value.
LT3013
OUT
GND
(12V/1.24V) • (–7mV) = –68mV
= 1.24V. At V
OUT
ADJ
OUT
/1.24V). For example, load regulation for an
R2
R1
OUT
+
= 12V, load regulation is:
3013 F01
V
OUT
3013fe