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LTM8033IY

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P26
LTM8033
10
8033fb
For more information www.linear.com/LTM8033
OPERATION
The LTM8033 is a standalone nonisolated step-down
switching DC/DC power supply that can deliver up to 3A of
output current. It is an EMC product; its radiated emissions
are so quiet that it can pass the stringent requirements of
EN55022 class B as a stand alone product. This µModule
provides a precisely regulated output voltage program
-
mable via one external resistor from 0.8V to 24V. The input
voltage range is 3.6V to 36V. Given that the LTM8033 is
a step-down converter, make sure that the input voltage
is high enough to support the desired output voltage and
load current.
As shown in the Block Diagram, the LTM8033 contains an
EMI filter, current mode controller, power switching ele
-
ment, power inductor, power Schottky diode and a modest
amount of input and output capacitance. The LTM8033 is
a fixed frequency P
WM regulator. The switching frequency
is set by simply connecting the appropriate resistor value
from the RT pin to GND.
An internal regulator provides power to the control circuitry.
The bias regulator normally draws power from the V
IN
pin, but if the BIAS pin is connected to an external volt-
age higher than 2.8V, bias power will be drawn from the
external
sour
ce (typically the regulated output voltage).
This improves efficiency. The RUN/SS pin is used to place
the LTM8033 in shutdown, disconnecting the output and
reducing the input current to less than 1μA.
To further optimize efficiency, the LTM8033 automatically
switches to Burst Mode operation in light load situations.
Between bursts, all circuitry associated with controlling
the output switch is shut down reducing the input supply
current to 50μA in a typical application.
The oscillator reduces the LTM8033’s operating frequency
when the voltage at the ADJ pin is low. This frequency
foldback helps to control the output current during start-
up and overload.
The LTM8033 contains a power good comparator which
trips when the ADJ pin is at roughly 90% of its regulated
value. The PGOOD output is an open-collector transistor
that is off when the output is in regulation, allowing an
external resistor to pull the PGOOD pin high. Power good
is valid when the LTM8033 is enabled and V
IN
is above
3.6V.
The LTM8033 is equipped with a thermal shutdown that
will inhibit power switching at high junction temperatures.
The activation threshold of this function, however, is above
125°C to avoid interfering with normal operation. Thus,
prolonged or repetitive operation under a condition in
which the thermal shutdown activates may damage or
impair the reliability of the device.
LTM8033
11
8033fb
For more information www.linear.com/LTM8033
APPLICATIONS INFORMATION
For most applications, the design process is straight for-
ward, summarized as follows:
• Look at Table 1 and find the row that has the desired
input range and output voltage.
• Apply the recommended C
IN
, C
FIN
, C
OUT
, R
ADJ
and R
T
values.
• Connect BIAS as indicated.
As the integrated input EMI filter may ring in response to
an application of a step input voltage, a bulk capacitance
may be applied between FIN and GND. See the Hot-Plug
-
ging Safely section for details.
While these component combinations have been tested
for proper operation, it is incumbent upon the user to
verify proper operation over the intended system’s line,
load and environmental conditions. Bear in mind that the
maximum output current is limited by junction tempera
-
ture, the relationship between the input and output voltage
magnitude and polarity and other factors. Please refer to
the graphs in the Typical Performance Characteristics
section for guidance.
The maximum frequency (and attendant R
T
value) at
which the LTM8033 should be allowed to switch is given
in Table 1 in the f
MAX
column, while the recommended
frequency (and R
T
value) for optimal efficiency over the
given input condition is given in the f
OPTIMAL
column.
There are additional conditions that must be satisfied if
the synchronization function is used. Please refer to the
Synchronization section for details.
Note: An input bulk capacitance is required at either V
IN
or FIN. Refer to the Typical Performance Characteristics
section for load conditions.
Capacitor Selection Considerations
The C
IN
, C
FIN
and C
OUT
capacitor values in Table 1 are the
minimum recommended values for the associated oper-
ating conditions. Applying capacitor values below those
indicated in T
able 1 is not recommended, and may result
in undesirable operation. Using larger values is generally
acceptable, and can yield improved dynamic response, if
it is necessar
y. Again, it is incumbent upon the user to
verify proper operation over the intended system’s line,
load and environmental conditions.
Ceramic capacitors are small, robust and have very low
ESR. However, not all ceramic capacitors are suitable.
X5R and X7R types are stable over temperature and ap
-
plied voltage and give dependable service. Other types,
including Y5V and Z5U have very large temperature and
voltage coefficients of capacitance. In an application cir
-
cuit they may have only a small fraction of their nominal
capacitance resulting in much higher output voltage ripple
than expected.
Ceramic capacitors are also piezoelectric.
In Burst Mode
operation, the LTM8033’s switching frequency depends
on the load current, and can excite a ceramic capacitor
at audio frequencies, generating audible noise. Since the
LTM8033 operates at a lower current limit during Burst
Mode operation, the noise is typically very quiet to a
casual ear.
If this audible noise is unacceptable, use a high perfor
-
mance electrolytic capacitor at the output. It may also be
a parallel combination of a ceramic capacitor and a low
cost electrolytic capacitor
.
A final precaution regarding ceramic capacitors concerns
the maximum input voltage rating of the L
TM8033. A
ceramic input capacitor combined with trace or cable
inductance forms a high Q (under damped) tank circuit.
If the LTM8033 circuit is plugged into a live supply, the
input voltage can ring to twice its nominal value, possibly
exceeding the device’s rating. This situation can be easily
avoided; see the Hot-Plugging Safely section.
LTM8033
12
8033fb
For more information www.linear.com/LTM8033
APPLICATIONS INFORMATION
Table 1. Recommended Component Values and Configuration (T
A
= 25°C)
V
IN
V
OUT
C
IN
C
FIN
C
OUT
BIAS R
ADJ
f
OPTIMAL
R
T(OPTIMAL)
f
MAX
R
T(MIN)
3.6V to 36V 0.8V 4.7µF, 50V, 1206 10µF, 50V, 1210
4 × 100µF, 6.3V, 1210
2.8V to 25V 30M 230kHz 182k 250kHz 169k
3.6V to 36V 1V 4.7µF, 50V, 1206 10µF, 50V, 1210
4 × 100µF, 6.3V, 1210
2.8V to 25V 1.87M 240kHz 174k 285kHz 147k
3.6V to 36V 1.2V 4.7µF, 50V, 1206 10µF, 50V, 1210
4 × 100µF, 6.3V, 1210
2.8V to 25V 953k 255kHz 162k 315kHz 130k
3.6V to 36V 1.5V 4.7µF, 50V, 1206 10µF, 50V, 1210
4 × 100µF, 6.3V, 1210
2.8V to 25V 549k 270kHz 154k 360kHz 113k
3.6V to 36V 1.8V 4.7µF, 50V, 1206 10µF, 50V, 1210
4 × 100µF, 6.3V, 1210
2.8V to 25V 383k 285kHz 147k 420kHz 95.3k
4.1V to 36V 2.5V 4.7µF, 50V, 1206 10µF, 50V, 1210
3 × 100µF, 6.3V, 1210
2.8V to 25V 226k 345kHz 118k 540kHz 71.5k
5.3V to 36V 3.3V 4.7µF, 50V, 1206 10µF, 50V, 1210 100µF, 6.3V, 1210 AUX 154k 425kHz 93.1k 675kHz 54.9k
7.5V to 36V 5V 4.7µF, 50V, 1206 4.7µF, 50V, 1206 100µF, 6.3V, 1210 AUX 93.1k 500kHz 76.8k 950kHz 36.5k
10.5V to 36V 8V 4.7µF, 50V, 1206 1µF, 50V, 1206 47µF, 16V, 1210 AUX 54.9k 700kHz 52.3k 1.45MHz 20.5k
20V to 36V 12V 2.2µF, 50V, 1206 1µF, 50V, 1206 47µF, 16V, 1210 AUX 34.8k 850kHz 41.2k 2.3MHz 9.09k
25.5V to 36V 18V 2.2µF, 50V, 1206 Open 22μF, 25V, 1812 AUX 22.6k 1.1MHz 29.4k 2.4MHz 8.25k
32.5V to 36V 24V 1µF, 50V, 1206 Open 22μF, 25V, 1812 2.8V to 20V 16.5k 1.2MHz 25.5k 2.4MHz 8.25k
3.6V to 15V 0.8V 4.7µF, 25V, 1206 10µF, 16V, 1210
4 × 100µF, 6.3V, 1210
V
IN
30M 230kHz 182k 575kHz 66.5k
3.6V to 15V 1V 4.7µF, 25V, 1206 10µF, 16V, 1210
4 × 100µF, 6.3V, 1210
V
IN
1.87M 240kHz 174k 660kHz 56.2k
3.6V to 15V 1.2V 4.7µF, 25V, 1206 10µF, 16V, 1210
4 × 100µF, 6.3V, 1210
V
IN
953k 255kHz 162k 760kHz 47.5k
3.6V to 15V 1.5V 4.7µF, 25V, 1206 10µF, 16V, 1210
4 × 100µF, 6.3V, 1210
V
IN
549k 270kHz 154k 840kHz 42.2k
3.6V to 15V 1.8V 4.7µF, 25V, 1206 10µF, 16V, 1210
4 × 100µF, 6.3V, 1210
V
IN
383k 285kHz 147k 1.0MHz 34.0k
4.1V to 15V 2.5V 4.7µF, 16V, 1206 10µF, 16V, 1210 3 x 100µF, 6.3V, 1210 V
IN
226k 345kHz 118k 1.3MHz 23.7k
5.3V to 15V 3.3V 4.7µF, 16V, 1206 10µF, 16V, 1210 100µF, 6.3V, 1210 AUX 154k 425kHz 93.1k 1.6MHz 17.8k
7.5V to 15V 5V 4.7µF, 16V, 1206 4.7µF, 50V, 1206 100µF, 6.3V, 1210 AUX 93.1k 500kHz 76.8k 2.4MHz 8.25k
10.5V to 15V 8V 2.2µF, 25V, 1206 Open 47µF, 16V, 1210 AUX 54.9k 700kHz 52.3k 2.4MHz 8.25k
9V to 24V 0.8V 4.7µF, 25V, 1206 4.7µF, 25V, 1206
4 × 100µF, 6.3V, 1210
V
IN
30M 270kHz 154k 360kHz 113k
9V to 24V 1V 4.7µF, 25V, 1206 4.7µF, 25V, 1206
4 × 100µF, 6.3V, 1210
V
IN
1.87M 285kHz 147k 410kHz 97.6k
9V to 24V 1.2V 4.7µF, 25V, 1206 4.7µF, 25V, 1206
4 × 100µF, 6.3V, 1210
V
IN
953k 295kHz 140k 475kHz 82.5k
9V to 24V 1.5V 4.7µF, 25V, 1206 4.7µF, 25V, 1206
4 × 100µF, 6.3V, 1210
V
IN
549k 310kHz 133k 550kHz 69.8k
9V to 24V 1.8V 4.7µF, 25V, 1206 4.7µF, 25V, 1206
3 × 100µF, 6.3V, 1210
V
IN
383k 330kHz 124k 620kHz 60.4k
9V to 24V 2.5V 4.7µF, 25V, 1206 4.7µF, 25V, 1206
2 × 100µF, 6.3V, 1210
V
IN
226k 345kHz 118k 800kHz 44.2k
9V to 24V 3.3V 4.7µF, 25V, 1206 4.7µF, 25V, 1206 100µF, 6.3V, 1210 AUX 154k 425kHz 93.1k 1.0MHz 34.0k
9V to 24V 5V 4.7µF, 25V, 1206 4.7µF, 25V, 1206 100µF, 6.3V, 1210 AUX 93.1k 500kHz 76.8k 1.4MHz 21.5k
10.5V to 24V 8V 2.2µF, 25V, 1206 1µF, 25V, 1206 47µF, 16V, 1210 AUX 54.9k 700kHz 52.3k 2.2MHz 9.76k
20V to 24V 12V 2.2µF, 25V
, 1206 1µF, 25V, 1206 47µF, 16V, 1210 AUX 34.8k 850kHz 41.2k 2.3MHz 9.09k
18V to 36V 0.8V 1µF, 50V, 1206 2.2µF, 50V, 1206
4 × 100µF, 6.3V, 1210
2.8V to 25V 30M 230kHz 182k 250kHz 169k
18V to 36V 1V 1µF, 50V, 1206 2.2µF, 50V, 1206
4 × 100µF, 6.3V, 1210
2.8V to 25V 1.87M 240kHz 174k 285kHz 147k
18V to 36V 1.2V 1µF, 50V, 1206 2.2µF, 50V, 1206
4 × 100µF, 6.3V, 1210
2.8V to 25V 953k 255kHz 162k 315kHz 130k
18V to 36V 1.5V 1µF, 50V, 1206 2.2µF, 50V, 1206
4 × 100µF, 6.3V, 1210
2.8V to 25V 549k 270kHz 154k 360kHz 113k
18V to 36V 1.8V 1µF, 50V, 1206 2.2µF, 50V, 1206
3 × 100µF, 6.3V, 1210
2.8V to 25V 383k 285kHz 147k 420kHz 95.3k
18V to 36V 2.5V 1µF, 50V, 1206 2.2µF, 50V, 1206
2 × 100µF, 6.3V, 1210
2.8V to 25V 226k 345kHz 118k 540kHz 71.5k
18V to 36V 3.3V 1µF, 50V, 1206 2.2µF, 50V, 1206 100µF, 6.3V, 1210 AUX 154k 425kHz 93.1k 675kHz 54.9k
18V to 36V 5V 1µF, 50V, 1206 1µF, 50V, 1206 47µF, 10V, 1210 AUX 93.1k 500kHz 76.8k 950kHz 36.5k
18V to 36V 8V 2.2µF, 50V, 1206 1µF, 50V, 1206 47µF, 16V, 1210 AUX 54.9k 700kHz 52.3k 1.45MHz 20.5k
Note: A bulk capacitor is required. Do not allow V
IN
+ BIAS above 56V.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P26

LTM8033IY

Mfr. #:
Buy LTM8033IY
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators [Tin-Lead SnPb BGA] Ultralow EMI 36Vin, 3A Step Down Module Regulator
Lifecycle:
New from this manufacturer.
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