Datasheet

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LTM8055/LTM8055-1

Rev C

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TYPICAL APPLICATION

FEATURES DESCRIPTION

36V

, 8.5A Buck-Boost

µModule Regulator

The LT M

8055/LTM8055-1 is a 36V

, buck-boost

µModule

(micromodule) regulator. Included in the pack-

age are

the switching controller, power switches, inductor

and support components. A resistor to set the switching

frequency, a resistor divider to set the output voltage,

and input and output capacitors are all that are needed

to complete the design. Other features such as input and

output average current regulation may be implemented

with just a few components. The LTM8055/LTM8055-1

operates over an input voltage range of 5V to 36V, and

can regulate output voltages between 1.2V and 36V. The

SYNC input and CLKOUT output allow easy synchronization.

The LTM8055/LTM8055-1 is housed in a compact over

molded ball

grid array (BGA) package suitable for auto-

mated assembly

by standard surface mount equipment.

The LTM8055/LTM8055-1 is RoHS compliant.

Buck-Boost Selection Table

LTM8054 LTM8055/LTM8055-1 LTM8056

(Operation) 36 36 58

Abs Max 40 40 60

OUT

Abs Max 40 40 60

OUT

(Peak)

24V

, 12V

OUT

5.4 8.5 5.5

Package 15 × 11.25mm ×

3.42mm BGA

15 × 15mm × 4.92mm BGA

Pin and Function Compatible

12V

OUT

from 5V

to 36V

Buck-Boost Regulator

APPLICATIONS

Complete Buck-Boost Switch Mode Power Supply

OUT

Equal, Greater, Less Than V

Wide Input Voltage Range: 5V to 36V

12V/3A Output from 6V

12V/6A Output from 12V

12V/8.5A Output from 24V

Up to 97.5% Efficient

Adjustable Input and Output Average Current Limits

Input and Output Current Monitors

Parallelable for Increased Output Current

Wide Output Voltage Range: 1.2V to 36V

Selectable Switching Frequency: 100kHz to 800kHz

Synchronization from 200kHz to 700kHz

External Compensation (LTM8055-1)

15mm × 15mm × 4.92mm BGA Package

High Power Battery-Operated Devices

Industrial Control

Solar Powered Voltage Regulator

Solar Powered Battery Charging

Maximum Output Current and Efficiency vs V

(V)

OUTPUT CURRENT (A)

EFFICIENCY (%)

8055 TA01b

402010 30

OUTPUT

CURRENT

EFFICIENCY

GNDLL MODE

LTM8055/

LTM8055-1

OUT

CLKOUT

INMON

OUTMON

RUN

CTL

SYNC

COMP

11k

8055 TA01a

22µF

25V

68µF

OUT

12V

4.7µF

50V

×2

5V TO 36V

= 600kHz

36.5k

100k

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Summary of content (26 pages)

PAGE 1
LTM8055/LTM8055-1 36VIN, 8.5A Buck-Boost µModule Regulator FEATURES n n n n n n n n n n n n n n Complete Buck-Boost Switch Mode Power Supply VOUT Equal, Greater, Less Than VIN Wide Input Voltage Range: 5V to 36V 12V/3A Output from 6VIN 12V/6A Output from 12VIN 12V/8.5A Output from 24VIN Up to 97.5% Efficient Adjustable Input and Output Average Current Limits Input and Output Current Monitors Parallelable for Increased Output Current Wide Output Voltage Range: 1.
PAGE 2
LTM8055/LTM8055-1 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) VIN, SVIN, VOUT, RUN, IIN, IOUT Voltage......................40V FB, SYNC, CTL, MODE Voltage....................................6V IINMON, IOUTMON Voltage..............................................6V LL Voltage..................................................................15V Maximum Junction Temperature (Notes 2, 3)........ 125°C Storage Temperature..............................
PAGE 3
LTM8055/LTM8055-1 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. RUN = 1.5V unless otherwise noted. (Note 2) PARAMETER Minimum Input Voltage Output DC Voltage Output DC Current Quiescent Current Into VIN (Tied to SVIN) Output Voltage Line Regulation Output Voltage Load Regulation Output RMS Voltage Ripple Switching Frequency CONDITIONS VIN = SVIN FB = VOUT Through 100k RFB = 100k/3.
PAGE 4
LTM8055/LTM8055-1 TYPICAL PERFORMANCE CHARACTERISTICS Efficiency vs Output Current (3.
PAGE 5
LTM8055/LTM8055-1 TYPICAL PERFORMANCE CHARACTERISTICS 10 6 4 6 4 2 4 6 8 OUTPUT CURRENT (A) 0 10 0 3 6 OUTPUT CURRENT (A) Input Current vs Output Current (24VOUT) 4 6 5 4 3 5VIN 12VIN 24VIN 36VIN 1 2 4 OUTPUT CURRENT (A) 0 6 0 1 2 3 4 OUTPUT CURRENT (A) 8055 G13 10 100 8 80 6 4 12VOUT 18VOUT 24VOUT 36VOUT 2 0 0 10 20 VIN (V) 30 40 8055 G16 8 6 4 5 3.
PAGE 6
LTM8055/LTM8055-1 TYPICAL PERFORMANCE CHARACTERISTICS Temperature Rise vs Output Current (8VOUT) TA = 25°C, unless otherwise noted.
PAGE 7
LTM8055/LTM8055-1 PIN FUNCTIONS GND (Bank 1, Pin L1): Tie these GND pins to a local ground plane below the LTM8055/LTM8055-1 and the circuit components. In most applications, the bulk of the heat flow out of the LTM8055/LTM8055-1 is through these pads, so the printed circuit design has a large impact on the thermal performance of the part. See the PCB Layout and Thermal Considerations sections for more details. Return the RFB1/RFB2 feedback divider to this net. MODE (Pin G2): Switching Mode Input.
PAGE 8
LTM8055/LTM8055-1 PIN FUNCTIONS IOUTMON (Pin L2): Output Current Monitor. This pin produces a voltage that is proportional to the voltage between VOUT and IOUT. IOUTMON will equal 1.2V when VOUT – IOUT = 58mV. This feature is generally useful only if a current sense resistor is applied between VOUT and IOUT. This is a high impedance output. Use a buffer to drive a load. (typical), but below 6V, the RUN pin input bias current is less than 1μA. Below 1.2V and above 0.
PAGE 9
LTM8055/LTM8055-1 OPERATION The LTM8055/LTM8055-1 is a standalone nonisolated buck-boost switching DC/DC power supply. The buck-boost topology allows the LTM8055/LTM8055-1 to regulate its output voltage for input voltages both above and below the magnitude of the output. The maximum output current depends upon the input voltage. Higher input voltages yield higher maximum output current. This converter provides a precisely regulated output voltage programmable via an external resistor divider from 1.
PAGE 10
LTM8055/LTM8055-1 APPLICATIONS INFORMATION For most applications, the design process is straight forward, summarized as follows: the graphs in the Typical Performance Characteristics section for guidance. 1. Look at Table 1 and find the row that has the desired input range and output voltage.
PAGE 11
LTM8055/LTM8055-1 APPLICATIONS INFORMATION gives the description and part numbers of electrolytic capacitors used in the LTM8055/LTM8055-1 development testing and design validation. Table 3. Switching Frequency vs RT Value FREQUENCY RT VALUE (kΩ) 100 453 200 147 300 84.5 Capacitor Selection Considerations The CIN and COUT capacitor values in Table 1 are the minimum recommended values for the associated operating conditions.
PAGE 12
LTM8055/LTM8055-1 APPLICATIONS INFORMATION pin, the two units will source the same current to the load, assuming each LTM8055/LTM8055-1 output current sense resistor is the same value. MASTER OUTPUT CURRENT SENSE RESISTOR TO LOAD VOUT IOUT IOUTMON UNITY GAIN BUFFER CTL SLAVE VOUT Paralleled LTM8055/LTM8055-1s should normally be allowed to switch in discontinuous mode to prevent current from flowing from the output of one unit into another; that is, the MODE pin should be tied to LL.
PAGE 13
LTM8055/LTM8055-1 APPLICATIONS INFORMATION the LTM8055/LTM8055-1 can still operate properly. Some examples of this are provided in the Typical Applications section. Soft-Start Soft-start reduces the input power sources’ surge currents by gradually increasing the controller’s current. As indicated in the Block Diagram, the LTM8055/LTM8055-1 has an internal soft-start RC network. Depending upon the load and operating conditions, the internal network may be sufficient for the application.
PAGE 14
LTM8055/LTM8055-1 APPLICATIONS INFORMATION Input Current Monitor (IINMON) The IINMON pin produces a voltage equal to approximately 20 times the voltage of IIN – VIN. Since the LTM8055/ LTM8055-1 input current limit engages when IIN – VIN = 50mV, IINMON will be 1V at maximum input current. Output Current Monitor (IOUTMON) The IOUTMON pin produces a voltage proportional to the voltage of VOUT – IOUT. Since the LTM8055/LTM8055-1 output current limit engages when VOUT – IOUT = 58mV, IOUTMON will be 1.
PAGE 15
LTM8055/LTM8055-1 APPLICATIONS INFORMATION LOAD CURRENT VIN ZENER DIODE Q VOUT LTM8055/ LTM8055-1 GND SOURCING LOAD R 8055 F05a Figure 5a. The MOSFET Q Dissipates Momentary Energy to GND. The Zener Diode and Resistor Are Chosen to Ensure That the MOSFET Turns On Above the Maximum VIN Voltage Under Normal Operation LOAD CURRENT VIN VOUT LTM8055/ LTM8055-1 GND RUN 10µF – + SOURCING LOAD EXTERNAL REFERENCE VOLTAGE from buck, buck-boost or boost operating modes, especially at lighter loads.
PAGE 16
LTM8055/LTM8055-1 APPLICATIONS INFORMATION 2. Place the CIN capacitor as close as possible to the VIN and GND connection of the LTM8055/LTM8055-1. board. Pay attention to the location and density of the thermal vias in Figure 6. The LTM8055/LTM8055-1 can benefit from the heat sinking afforded by vias that connect to internal GND planes at these locations, due to their proximity to internal power handling components. The optimum number of thermal vias depends upon the printed circuit board design.
PAGE 17
LTM8055/LTM8055-1 APPLICATIONS INFORMATION an energized supply, the input network should be designed to prevent this overshoot. This can be accomplished by installing a small resistor in series with VIN, but the most popular method of controlling input voltage overshoot is to add an electrolytic bulk capacitor to the VIN net. This capacitor’s relatively high equivalent series resistance damps the circuit and eliminates the voltage overshoot.
PAGE 18
LTM8055/LTM8055-1 APPLICATIONS INFORMATION JUNCTION-TO-AMBIENT RESISTANCE (JESD 51-9 DEFINED BOARD) CASE (TOP)-TO-AMBIENT RESISTANCE JUNCTION-TO-CASE (TOP) RESISTANCE JUNCTION JUNCTION-TO-BOARD RESISTANCE AMBIENT JUNCTION-TO-CASE CASE (BOTTOM)-TO-BOARD (BOTTOM) RESISTANCE RESISTANCE BOARD-TO-AMBIENT RESISTANCE 8055 F07 µMODULE CONVERTER Figure 7 Given these definitions, it should now be apparent that none of these thermal coefficients reflects an actual physical operating condition of a µModule co
PAGE 19
LTM8055/LTM8055-1 TYPICAL APPLICATIONS 12VOUT Fan Power from 3VIN to 36VIN with Analog Current Control and 2A Input Current Limiting Maximum Output Current vs CTL Voltage 1µF 50V VIN IIN SVIN LTM8055/ LTM8055-1 0.05Ω VOUT VOUT 12V MAX IOUT FAN 10µF 50V RUN COMP SS SYNC CTL RT LL MODE 36.5k 100k GND CLKOUT IINMON IOUTMON FB 22µF 25V + 68µF 25V 11.0k 0.8 0.6 0.4 0.2 8055 TA02a 0 fSW = 600kHz 0.2V TO 1.2V CONTROL RANGE DAC 12VIN 1.0 OUTPUT CURRENT (A) VIN 3V TO 36V 0.022Ω 1.2 0 0.
PAGE 20
LTM8055/LTM8055-1 TYPICAL APPLICATIONS 3.3VOUT from 9VIN to 24VIN with 5A Accurate Current Limit and Output Current Monitor Output Voltage vs Output Current 4.0 VIN VIN 9V TO 24V LTM8055/ LTM8055-1 SVIN VOUT 0.011Ω IOUT VOUT 3.3V 3.5 10µF 50V 36.5k RUN CTL SS SYNC COMP RT LL 100k MODE GND CLKOUT IINMON IOUTMON FB 22µF 6.3V OUTPUT CURRENT MONITOR + 56.2k OUTPUT VOLTAGE (V) IIN 100µF 6.3V 3.0 2.5 2.0 1.5 1.0 0.
PAGE 21
LTM8055/LTM8055-1 TYPICAL APPLICATIONS Two LTM8055/LTM8055-1s Powered from Different Input Sources to Run a Single Load. Each LTM8055/LTM8055-1 Draws No More Than 1.8A from Its Respective Power Source, and Are Synchronized 180° Out Of Phase with Each Other 0.025Ω SUPPLY 1 6V TO 36VIN VIN SVIN LTM8055/ LTM8055-1 IOUT IIN 10µF 50V RUN CTL SS SYNC COMP RT CLKOUT LL MODE 47pF 36.5k 0.
PAGE 22
LTM8055/LTM8055-1 PACKAGE DESCRIPTION Table 4.
PAGE 23
LTM8055/LTM8055-1 PACKAGE PHOTO Rev C For more information www.analog.com Downloaded from Arrow.com.
PAGE 24
0.635 ±0.025 Ø 121x 4 PIN “A1” CORNER E PACKAGE TOP VIEW 2.540 SUGGESTED PCB LAYOUT TOP VIEW 1.270 aaa Z 0.3175 0.000 0.3175 Downloaded from Arrow.com. 1.270 24 2.540 D X For more information www.analog.com 6.350 5.080 3.810 2.540 1.270 0.000 1.270 2.540 3.810 5.080 6.350 Y aaa Z NOM 4.92 0.60 4.32 0.78 0.635 15.00 15.00 1.27 12.70 12.70 0.32 4.00 A A2 MAX 5.12 0.70 4.42 0.85 0.660 NOTES DETAIL B PACKAGE SIDE VIEW DIMENSIONS b1 0.37 4.05 0.15 0.10 0.20 0.30 0.
PAGE 25
LTM8055/LTM8055-1 REVISION HISTORY REV DATE DESCRIPTION A 01/16 Added Buck-Bost Selection Table PAGE NUMBER 1 B 05/17 Added text to IOUTMON (pin L2) 8 C 08/18 Added LTM8055-1 1, 2, 7, 9, 10, 23 Rev C Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use.
PAGE 26
LTM8055/LTM8055-1 TYPICAL APPLICATION Input Current vs Input Voltage, IOUT = 3A 14.4V, 3A Lead-Acid Battery Charger Input Current Limited to 2.1A 2.5 1µF 50V VIN SVIN IIN 0.02Ω VOUT LTM8055/ LTM8055-1 IOUT + 100k 10µF 50V 36.5k RUN CTL SS SYNC COMP RT LL MODE GND VOUT 14.4V 47µF 25V INPUT CURRENT (A) 0.022Ω VIN 3V TO 36V 2.0 1.5 1.0 0.5 CLKOUT IINMON IOUTMON FB 22µF 25V 0 9.