Datasheet

LTM8020
5
8020fd
PIN FUNCTIONS
V
IN
(Pins A1, A2): The V
IN
pins supply current to the
LTM8020’s internal regulator and to the internal power
switch. These pins must be locally bypassed with an
external, low ESR capacitor of at least 1μF.
V
OUT
(Pins A4, A5, B4, B5, C4, C5): Power Output Pins.
An external capacitor is connected from V
OUT
to GND in
most applications. Apply output load between these pins
and GND.
BIAS (Pin C3): The BIAS pin connects to the internal
boost Schottky diode and to the internal regulator. Tie to
V
OUT
when V
OUT
> 3V or to another DC voltage greater
than 3V otherwise. When BIAS > 3V the internal circuitry
will be powered from this pin to improve efficiency. Main
regulator power will still come from V
IN
.
SHDN (Pin C1): The SHDN pin is used to put the LTM8020 in
shutdown mode. Tie to ground to shut down the LTM8020.
Apply 2V or more for normal operation. If the shutdown
feature is not used, tie this pin to V
IN
.
GND (Pins C2, D1, D2, D3, D4, D5, E2, E3, E4, E5): The
GND connections serve as the main signal return and the
primary heat sink for the LTM8020. Tie the GND pins to
a local ground plane below the LTM8020 and the circuit
components. Return the feedback divider to this signal.
ADJ (Pin E1): The LTM8020 regulates its ADJ pin to 1.25V.
Connect the adjust resistor from this pin to GND. The
value of this adjust resistor is determined by the equation
R
ADJ
= 623.75/(V
OUT
– 1.25), where R
ADJ
is in kΩ. Note
that the ADJ pin is open circuit if V
OUT
= 1.25V.
TYPICAL PERFORMANCE CHARACTERISTICS
T
A
= 25°C unless otherwise noted.
INPUT VOLTAGE (V)
0
0
TEMPERATURE RISE (°C)
5
10
15
20
10 20 30 5040
8020 G13
25
3.3V
OUT
5V
OUT
Temperature Rise vs Input
Voltage (Full Load, T
A
= 25°C)
Turn-On Behavior
(6V
IN
, 3.3V
OUT
, No Load)
V
OUT
2V/DIV
SHDN
5V/DIV
INPUT CURRENT
100mA/DIV
50μs/DIV
8020 G14
FREQUENCY (MHz)
0
EMISSIONS LEVEL (dBμV/m)
50
70
90
800
8020 G15
30
10
40
60
80
20
0
–10
200
400
600
1000
36V
IN
5V
OUT
FULL LOAD
EN55022
CLASS B LIMIT
Radiated Emissions