Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPSU ComponentsDC/DC converter (SMD) 5 V 500 mA No. of outputs: 1 x

LTM8021

8021fc

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

36V

, 500mA

Step-Down DC/DC

Module

The LTM

8021 is a 36V

500mA, step-down DC/DC

μModule

. Included in the package are the switching

controller, power switches, inductor, and all support

components. Operating over an input voltage range of 3V

to 36V, the LTM8021 supports an output voltage range of

0.8V to 5V, set by a single resistor. Only an output and

bulk input capacitor are needed to ﬁ nish the design.

The low proﬁ le package (2.82mm) enables utilization of

unused space on the bottom of PC boards for high den-

sity point of load regulation. A built-in soft-start timer is

adjustable with just a resistor and capacitor.

The LTM8021 is packaged in a thermally enhanced,

compact (11.25mm × 6.25mm) and low proﬁ le (2.82mm)

overmolded land grid array (LGA) package suitable

for automated assembly by standard surface mount

equipment. The LTM8021 is RoHS compliant.

to 36V

, 5V/500mA μModule Regulator

Complete Switch Mode Power Supply

Wide Input Voltage Range: 3V to 36V

500mA Output Current

0.8V to 5V Output Voltage

Fixed 1.1MHz Switching Frequency

Current Mode Control

(e4) RoHS Compliant Package with Gold

Pad Finish

Programmable Soft-Start

Tiny, Low Proﬁ le (11.25mm × 6.25mm × 2.82mm)

Surface Mount LGA Package

Automotive Battery Regulation

Power for Portable Products

Distributed Supply Regulation

Industrial Supplies

Wall Transformer Regulation

Efﬁ ciency and Power Loss

LTM8021

8021 TA01a

7V TO

36V

OUT

5V AT 500mA

1μF

2.2μF

19.1k

RUN/SS

GND ADJ

BIAS

OUT

*RUNNING VOLTAGE RANGE. PLEASE REFER TO THE

APPLICATIONS INFORMATION SECTION FOR START-UP DETAILS.

POWER LOSS (mW)

100

200

300

450

400

150

250

350

8021 TA01b

LOAD CURRENT (mA)

1.00

EFFICIENCY (%)

10.00 100.00

1000.00

POWER

LOSS

EFFICIENCY

L, LT, LTC, LTM, μModule, Linear Technology and the Linear logo are registered trademarks of

Linear Technology Corporation. All other trademarks are the property of their respective owners.

Summary of content (16 pages)

PAGE 1
LTM8021 36VIN, 500mA Step-Down DC/DC µModule FEATURES DESCRIPTION n The LTM®8021 is a 36VIN 500mA, step-down DC/DC μModule®. Included in the package are the switching controller, power switches, inductor, and all support components. Operating over an input voltage range of 3V to 36V, the LTM8021 supports an output voltage range of 0.8V to 5V, set by a single resistor. Only an output and bulk input capacitor are needed to ﬁnish the design.
PAGE 2
LTM8021 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) VIN, RUN/SS Voltage.................................................40V RUN/SS Above VIN ......................................................3V ADJ Voltage ................................................................5V BIAS Voltage ...............................................................7V VOUT Voltage .............................................................10V Internal Operating Temperature Range (Note 2)......................
PAGE 3
LTM8021 ELECTRICAL CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C, VIN = 10V, VRUN/SS = 10V, VBIAS = 3V, RADJ = 31.6k. SYMBOL PARAMETER CONDITIONS VOUT(DC) DC Output Voltage VIN = 24V, 0 ≤ IOUT ≤ 500mA RADJ = 31.6k, 0.1% MIN TYP MAX VOUT(AC_RMS) Output Voltage Ripple (RMS) VIN = 24V, IOUT = 250mA COUT = 2.
PAGE 4
LTM8021 TYPICAL PERFORMANCE CHARACTERISTICS VOUT = 1.8V 80 VIN = 5V 75 VIN = 12V 70 VIN = 24V 65 VIN = 36V 60 VOUT = 2.5V 85 EFFICIENCY (%) 85 EFFICIENCY (%) Efﬁciency vs Load Current 90 Efﬁciency vs Load Current 90 VIN = 5V 80 VIN = 12V 75 VIN = 24V VIN = 36V 65 55 0 50 50 100 150 200 250 300 350 400 450 500 LOAD CURRENT (mA) 50 100 150 200 250 300 350 400 450 500 LOAD CURRENT (mA) IBIAS vs Load Current 9 VOUT = 0.8V VIN = 12V VOUT = 1.8V VIN = 3.4V 8 VIN = 3.
PAGE 5
LTM8021 TYPICAL PERFORMANCE CHARACTERISTICS Input Current vs Output Current VIN = 5V INPUT CURRENT (mA) VOUT = 2.5V 200 150 VOUT = 1.8V 100 50 200 VOUT = 3.3V 150 VOUT = 2.5V 100 100 50 100 150 200 250 300 350 400 450 500 OUTPUT CURRENT (mA) VOUT = 2.5V 60 40 VOUT = 1.8V 8021 G09 0 50 100 150 200 250 300 350 400 450 500 OUTPUT CURRENT (mA) 8021 G11 Minimum Input Running Voltage vs Output Voltage 7 VO = 3.
PAGE 6
LTM8021 PIN FUNCTIONS VIN (Bank 1): The VIN pin supplies current to the LTM8021’s internal regulator and to the internal power switch. This pin must be locally bypassed with an external, low ESR capacitor of at least 1μF. VOUT (Bank 2): Power Output Pins. An external capacitor is connected from VOUT to GND in most applications. Apply output load between these pins and GND pins. BIAS (Pin H3): The BIAS pin connects to the internal boost Schottky diode and to the internal regulator.
PAGE 7
LTM8021 OPERATION The LTM8021 is a standalone nonisolated step-down switching DC/DC power supply. It can deliver up to 500mA of DC output current with only bulk external input and output capacitors. This module provides a precisely regulated output voltage programmable via one external resistor from 0.8VDC to 5VDC . The input voltage range is 3V to 36V. Given that the LTM8021 is a step-down converter, make sure that the input voltage is high enough to support the desired output voltage and load current.
PAGE 8
LTM8021 APPLICATIONS INFORMATION Table 1. Recommended Component Values and Conﬁguration VIN RANGE VOUT CIN COUT RADJ BIAS 3.4V to 36V 0.8V 4.7μF 100μF 1210 8.2M 3V to 7V 3.4V to 36V 1.2V 4.7μF 100μF 1210 200k 3V to 7V 3.4V to 36V 1.5V 4.7μF 100μF 1210 115k 3V to 7V 3.4V to 36V 1.8V 2.2μF 100μF 1210 78.7k 3V to 7V 3.5V to 36V 2V 2.2μF 100μF 1210 66.5k 3V to 7V 4V to 36V 2.2V 1μF 22μF 1206 57.6k 3V to 7V 4V to 36V 2.5V 1μF 10μF 0805 47.5k 3V to 7V 5V to 36V 3.
PAGE 9
LTM8021 APPLICATIONS INFORMATION If this audible noise is unacceptable, use a high performance electrolytic capacitor at the output. This output capacitor can be a parallel combination of a 1μF ceramic capacitor and a low cost electrolytic capacitor. Capacitor Selection Considerations The CIN and COUT capacitor values in Table 1 are the minimum recommended values for the associated operating conditions.
PAGE 10
LTM8021 APPLICATIONS INFORMATION Soft-Start Shorted Input Protection The RUN/SS pin can be used to soft-start the LTM8021, reducing the maximum input current during start-up. The RUN/SS pin is driven through an external RC ﬁlter to create a voltage ramp at this pin. Figure 2 shows the soft-start circuit. By choosing a large RC time constant, the peak start-up current can be reduced to the current that is required to regulate the output, with no overshoot.
PAGE 11
LTM8021 APPLICATIONS INFORMATION PCB Layout Hot-Plugging Safely Most of the problems associated with the PCB layout have been alleviated or eliminated by the high level of integration of the LTM8021. The LTM8021 is nevertheless a switching power supply, and care must be taken to minimize EMI and ensure proper operation. Even with the high level of integration, one may fail to achieve a speciﬁed operation with a haphazard or poor layout. See Figure 4 for a suggested layout.
PAGE 12
LTM8021 APPLICATIONS INFORMATION CLOSING SWITCH SIMULATES HOT PLUG IIN VIN DANGER VIN 20V/DIV RINGING VIN MAY EXCEED ABSOLUTE MAXIMUM RATING LTM8021 + 4.7μF LOW IMPEDANCE ENERGIZED 24V SUPPLY IIN 10A/DIV STRAY INDUCTANCE DUE TO 6 FEET (2 METERS) OF TWISTED PAIR 20μs/DIV (5a) LTM8021 + + 22μF AI.EI. VIN 20V/DIV 4.7μF IIN 10A/DIV (5b) 0.7Ω LTM8021 20μs/DIV VIN 20V/DIV + 0.1μF 4.7μF IIN 10A/DIV (5c) 20μs/DIV 8021 F05 Figure 5.
PAGE 13
LTM8021 TYPICAL APPLICATIONS 1.8V Step-Down Converter 0.8V Step-Down Converter LTM8021 VIN* 3.4V TO 36V VIN 5V VIN 5V BIAS RUN/SS 1μF LTM8021 VIN* 3.4V TO 36V VOUT 0.8V AT 500mA VOUT GND VOUT 1.8V AT 500mA VOUT BIAS RUN/SS 100μF GND ADJ 100μF ADJ 1μF 78.7k 8021 TA02 8021 TA03 *RUNNING VOLTAGE RANGE. PLEASE REFER TO THE APPLICATIONS INFORMATION SECTION FOR START-UP DETAILS. *RUNNING VOLTAGE RANGE. PLEASE REFER TO THE APPLICATIONS INFORMATION SECTION FOR START-UP DETAILS.
PAGE 14
LTM8021 PACKAGE DESCRIPTION LGA Package 35-Lead (11.25mm × 6.25mm × 2.82mm) (Reference LTC DWG # 05-08-1805 Rev A) 11.250 BSC aaa Z X 2.72 – 2.92 Y MOLD CAP 6.250 BSC SUBSTRATE 0.27 – 0.37 PAD 1 CORNER Z bbb Z 2.40 – 2.60 DETAIL A aaa Z PACKAGE TOP VIEW 4 4.445 3.175 1.905 0.635 0.0000 0.635 1.905 3.175 4.445 DETAIL A PACKAGE SIDE VIEW 8.890 BSC 0.605 – 0.665 PADS SEE NOTES 3 5 2.540 1.270 4 0.605 – 0.665 5.080 BSC 0.0000 0.9525 1.270 1.5875 3 2 1.270 BSC 1 0.9525 0.
PAGE 15
LTM8021 PACKAGE DESCRIPTION LTM8021 Pinout (Sorted by Pin Number) PIN SIGNAL DESCRIPTION A1 RUN/SS A2 ADJ A4 VIN A5 VIN B1 GND B2 GND B4 VIN B5 VIN C1 GND C2 GND D1 GND D2 GND D3 GND D4 GND D5 GND E1 GND E2 GND E3 GND E4 GND E5 GND F1 GND F2 GND F3 VOUT F4 VOUT F5 VOUT G1 GND G2 GND G3 VOUT G4 VOUT G5 VOUT H1 GND H2 GND H3 BIAS H4 VOUT H5 VOUT 8021fc Information furnished by Linear Technology Corporation is believed to be accurate and
PAGE 16
LTM8021 TYPICAL APPLICATION 3.3V Step-Down Converter LTM8021 VIN* 5.5V TO 36V VIN VOUT RUN/SS BIAS GND 1μF VOUT 3.3V AT 500mA ADJ 32.4k 4.7μF 8021 TA06 *RUNNING VOLTAGE RANGE. PLEASE REFER TO THE APPLICATIONS INFORMATION SECTION FOR START-UP DETAILS. RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTM4600 10A DC/DC μModule Basic 10A DC/DC μModule, 15mm × 15mm × 2.8mm LGA LTM4600HVMPV Military Plastic 10A DC/DC μModule –55°C to 125°C Operation, 15mm × 15mm × 2.