Datasheet

ManualsBrandsLinear Technology ManualsDC / DC Fixed Switching RegulatorsSwitching Regulator IC 5V QFN-

LT8619/LT8619-5

Rev A

For more information www.analog.com

TYPICAL APPLICATION

FEATURES DESCRIPTION

60V, 1.2A Synchronous Monolithic Buck

Regulator with 6µA Quiescent Current

The LT

8619 is a compact, high efficiency, high speed

synchronous monolithic step-down switching regulator

that consumes only 6μA of quiescent current. The LT8619

can deliver 1.2A of continuous current. Top and bottom

power switches are included with all necessary circuitry

to minimize the need for external components. Low ripple

Burst Mode

operation enables high efficiency down to

very low output currents while keeping the output ripple

to 10mV

P-P

. A SYNC pin allows forced continuous mode

operation synchronized to an external clock. Internal com

pensation with peak current mode topology allows the use

of small inductors and results in fast transient response

and good loop stability. The EN/UV pin has an accurate 1V

threshold and can be used to program V

undervoltage

lockout or to shut down the LT8619, reducing the input

supply current to below 0.6μA. The PG flag signals when

OUT

is within ±7.5% of the programmed output voltage.

The LT8619 is available in a small 16-lead MSOP and

10-lead 3mm × 3mm DFN packages with exposed pad

for low thermal resistance.

APPLICATIONS

Wide Input Voltage Range: 3V to 60V

Fast Minimum Switch-On Time: 30ns

Ultralow Quiescent Current Burst Mode Operation:

6μA I

Regulating 12V

to 3.3V

OUT

10mV

P-P

Output Ripple at No Load

Synchronizable/Programmable Fixed Frequency

Forced Continuous Mode Operation: 300kHz

to2.2MHz

High Efficiency Synchronous Operation:

92% Efficiency at 0.5A, 5V

OUT

from 12V

90% Efficiency at 0.5A, 3.3V

OUT

from 12V

Low Dropout: 360mV at 0.5A

Low EMI

Accurate 1V Enable Pin Threshold

Internal Soft-Start and Compensation

Power Good Flag

Small Thermally Enhanced 16-Lead MSOP Package

and 10-Lead (3mm × 3mm) DFN Packages

12V Automotive Systems

12V and 24V Commercial Vehicles

48V Electric and Hybrid Vehicles

Industrial Supplies

All registered trademarks and trademarks are the property of their respective owners.

Efficiency at V

OUT

= 5V5V, 1.2A Step-Down Converter

L = 10µH, IHLP-2020BZ-01

= 48V

= 24V

= 12V

OSC

= 700kHz

Burst Mode

OPERATION

EFFICIENCY

LOAD CURRENT (mA)

0.001

0.01

0.1

100

10k

100

0.0001

0.001

0.01

EFFICIENCY (%)

POWER LOSS (W)

8619 TA01b

0.1

Efﬁciency at V

OUT

= 5V

POWER LOSS

LT8619-5

10µH

66.5k

OFF ON

0.1µF

22µF

8619 TA01a

1µF

2.2µF

6V TO 60V

OUT

1.2A

BST

BIAS

OUT

INTV

GNDSYNC

OSC

= 700kHz

EN/UV

100k

L = VISHAY IHLP-2020BZ-01

OUT

= TDK C3225X7R1C226K250

Document Feedback

Downloaded from Arrow.com.

Summary of content (28 pages)

PAGE 1
LT8619/LT8619-5 60V, 1.2A Synchronous Monolithic Buck Regulator with 6µA Quiescent Current FEATURES DESCRIPTION Wide Input Voltage Range: 3V to 60V nn Fast Minimum Switch-On Time: 30ns nn Ultralow Quiescent Current Burst Mode Operation: nn 6μA I Regulating 12V to 3.3V Q IN OUT nn 10mV Output Ripple at No Load P-P nn Synchronizable/Programmable Fixed Frequency Forced Continuous Mode Operation: 300kHz to 2.2MHz nn High Efficiency Synchronous Operation: nn 92% Efficiency at 0.
PAGE 2
LT8619/LT8619-5 ABSOLUTE MAXIMUM RATINGS (Notes 1, 2) VIN, EN/UV.................................................................60V BIAS...........................................................................30V BST Pin Above SW Pin................................................4V PG, SYNC, OUT............................................................6V FB ................................................................................2V Operating Junction Temperature (Note 3) LT8619E, LT8619E-5...
PAGE 3
LT8619/LT8619-5 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VEN/UV = 2V unless otherwise noted (Notes 2, 3) PARAMETER CONDITIONS MIN TYP MAX UNITS Switching Loop VIN Minimum Input Voltage VIN Quiescent Current at No Load VIN = 12V, VEN/UV = 0V 0.6 0.6 1.0 3.0 µA µA l 6 6 10 18 µA µA VIN = 12V, VOUT = 3.3V, RT = 66.5k, VEN/UV = 2V, Floats SYNC 10 µA VIN = 12V, VOUT = 3.
PAGE 4
LT8619/LT8619-5 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VEN/UV = 2V unless otherwise noted (Notes 2, 3) PARAMETER CONDITIONS MIN TYP MAX UNITS Switch, Logic and Power Good Top Switch On-Resistance ILOAD = 0.1A Bottom Switch On-Resistance ILOAD = 0.1A EN/UV Power-On Threshold EN/UV Rising l 0.94 EN/UV Power-On Hysteresis 0.45 Ω 0.22 Ω 1.0 1.1 40 0.34 0.56 V mV 0.
PAGE 5
LT8619/LT8619-5 TYPICAL PERFORMANCE CHARACTERISTICS Burst Mode OPERATION 90 80 80 70 70 PULSESKIPPING MODE 60 50 FORCED CONTINUOUS MODE 40 30 VIN = 12V fOSC = 700kHz L = 10µH IHLP-2020BZ-01 20 10 0 0.001 0.01 700kHz Efficiency at V OUT = 3.3V 0.1 1 10 100 LOAD CURRENT (mA) 1k 90 60 50 FORCED CONTINUOUS MODE 40 30 VIN = 12V fOSC = 700kHz L = 10µH IHLP-2020BZ-01 10 0 0.001 0.01 0.1 1 10 100 LOAD CURRENT (mA) 1k 2MHz Efficiency Efficiency at at VVOUT = 3.
PAGE 6
LT8619/LT8619-5 TYPICAL PERFORMANCE CHARACTERISTICS VOUT = 3.3V VIN = 12V fOSC = 700kHz NO LOAD FORCED CONTINUOUS MODE 0.75 0.50 0.25 0 –0.25 –0.50 Line Regulation 0.10 VIN = 12V VOUT = 3.3V fSW = 700kHz FORCED CONTINUOUS MODE 0.1 ∆VOUT (%) ∆VOUT (%) Load Regulation 0.2 VOUT = 2.4V, NO LOAD fSW = 400kHz FORCED CONTINUOUS MODE 0.05 ∆VOUT (%) 1.00 0 0 –0.05 –0.1 –0.75 –0.2 25 50 75 100 125 150 TEMPERATURE (°C) 0 0.2 0.4 0.6 0.8 LOAD CURRENT (A) 8619 G10 1.
PAGE 7
LT8619/LT8619-5 TYPICAL PERFORMANCE CHARACTERISTICS 60 0.2A LOAD 40 0.5A LOAD 20 0 –50 –25 0 160 0.5A LOAD NO LOAD 150 140 –50 –25 25 50 75 100 125 150 TEMPERATURE (°C) 0 8619 G19 Power Good Delay 25 10 20 40 60 VFB – VPGTH (mV) 80 IBIAS vs fSW 10 IBIAS (mA) IBIAS (mA) NO LOAD 4 2 0.6 1.0 1.4 fSW (MHz) 1.8 2.2 NPG VFB RISING –7.5 NPG VFB FALLING –10.0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 8619 G21 12 IBIAS vs Load VIN = 12V VOUT = 3.
PAGE 8
LT8619/LT8619-5 TYPICAL PERFORMANCE CHARACTERISTICS Forced Continuous Mode No Load Switching Waveform Forced Continuous Mode Switching Waveform at Minimum On-time IL 200mA/DIV VOUT (AC) 2mV/DIV SW 20V/DIV IL 200mA/DIV SW (ZOOM IN) 10V/DIV SW 10V/DIV 200ns/DIV TOP = 200ns/DIV, BOT = 5ns/DIV, PERSISTENCE MODE 8619 G28 VIN = 12V, VOUT = 3.3V fSW = 2MHz, L = 3.3μH, COUT = 22μF VIN = 53.7V, VOUT = 3.3V, 0.5A LOAD fSW = 2MHz, L = 3.
PAGE 9
LT8619/LT8619-5 TYPICAL PERFORMANCE CHARACTERISTICS VOUT = 2.4V Start-Up Dropout Performance VIN 1V/DIV VOUT 1V/DIV PG 2V/DIV SW 5V/DIV VOUT = 5V Start-Up Dropout Performance VIN 1V/DIV VIN VOUT 1V/DIV VOUT VOUT 1s/DIV VIN 8619 G34 PG 2V/DIV SW 5V/DIV VOUT = 2.
PAGE 10
LT8619/LT8619-5 PIN FUNCTIONS (DFN/MSOP) NC (Pin 1, 3, 13, MSOP Only): No Connect. These pins are not connected to the internal circuitry. VIN (Pin 1/Pin 2): The VIN pin supplies current to the LT8619 internal circuitry and to the internal topside power switch. Be sure to place the positive terminal of the input bypass capacitor as close as possible to the VIN pin, and the negative capacitor terminal as close as possible to the GND pin.
PAGE 11
LT8619/LT8619-5 BLOCK DIAGRAM VIN CIN R3 OPT VIN EN/UV + 1V – R4 OPT + ENABLE – ICMP SYNC UVLO CLK OSC 0.3MHz–2.2MHz SLOPE COMP RT RT S BURST DETECT RC VIN BIAS 3.3V LDO INTVCC R CINTVCC Q BST CB VC CC INTVCC SW OV L VOUT LOGIC COUT R1 C1 EA + – + ISS GND 0.8V VREF FB/OUT CSS R2 – NPG + PG PG 0.74V VOUT = 5V GLITCH FILTER + PPG – OV 0.83V – 0.86V OV + 8619 BD Rev A For more information www.analog.com Downloaded from Arrow.com.
PAGE 12
LT8619/LT8619-5 OPERATION The LT8619 is a monolithic, constant frequency current mode step-down DC/DC converter. An oscillator, with frequency set using a resistor on the RT pin, turns on the internal top power switch at the beginning of each clock cycle. Current in the inductor then increases until the current comparator trips and turns off the top power switch. The peak inductor current at which the top switch turns off is controlled by the voltage on the internal VC node.
PAGE 13
LT8619/LT8619-5 APPLICATIONS INFORMATION Achieving Ultralow Quiescent Current 1k As the output load decreases, the frequency of single current pulses decreases (see Figure 1) and the percentage of time the LT8619 is in sleep mode increases, resulting in much higher light load efficiency than for typical converters. For a typical application, when the output is not loaded, by maximizing the time between pulses, the regulator quiescent approaches 6µA.
PAGE 14
LT8619/LT8619-5 APPLICATIONS INFORMATION FB Resistor Network The output voltage is programmed with a resistor divider between VOUT and the FB pin. Choose the resistor values according to: ⎛V ⎞ R1= R2 ⎜ OUT – 1⎟ ⎝ 0.8V ⎠ Reference designators refer to the Block Diagram. 1% resistors are recommended to maintain output voltage accuracy. If low input quiescent current and good light-load efficiency are desired, use a large resistor value for the FB resistor divider.
PAGE 15
LT8619/LT8619-5 APPLICATIONS INFORMATION is the minimum top switch on-time at the loading condition as shown in Figure 5. Figure 6 shows the relationship between the maximum input voltage vs the switching frequency. If a smaller RT is selected, to ensure that the regulator is switching at the higher frequency as illustrated in Figure 4, the maximum input supply voltage has to be lowered; and it needs to be further reduced if the load is decreased or removed. 80 VOUT = 3.3V fSW = 2MHz L = 3.
PAGE 16
LT8619/LT8619-5 APPLICATIONS INFORMATION For low VIN applications that cannot allow deviation from the programmed oscillator frequency, use the following formula to set the switching frequency: VIN(MIN) = VSW(BOT) + VOUT 1– t OFF(MIN) • fOSC + VSW(TOP) – VSW(BOT) where VIN(MIN) is the minimum input voltage without skipped cycles, VOUT is the output voltage, VSW(TOP) and VSW(BOT) are the internal switch drops (~0.54V, ~0.
PAGE 17
LT8619/LT8619-5 APPLICATIONS INFORMATION stay in sleep mode longer between each pulse. This can be achieved by using a larger value inductor, and should be considered independent of switching frequency when choosing an inductor. For example, while a lower inductor value would typically be used for a high switching frequency application, if high light load efficiency is desired, a higher inductor value should be chosen.
PAGE 18
LT8619/LT8619-5 APPLICATIONS INFORMATION an output capacitor, i.e. high volumetric efficiency with extremely low equivalent resistance. There is a downside however; the high K dielectric material exhibits a substantial temperature and voltage coefficient, meaning that its capacitance varies depending on the operating temperature and applied voltage. X7R capacitors provide a range intermediate capacitance values which varies only ±15% over the temperature range of –55°C to 125°C.
PAGE 19
LT8619/LT8619-5 APPLICATIONS INFORMATION threshold can be adjusted by setting the values R3 and R4 such that they satisfy the following equation: ⎛ R3 ⎞ VIN(EN/UV) = ⎜ 1+ • 1V ⎝ R4 ⎟⎠ where the LT8619 will remain off until VIN is above VIN(EN/UV). Due to the comparator’s hysteresis, switching will not stop until the input falls slightly below VIN(EN/UV).
PAGE 20
LT8619/LT8619-5 APPLICATIONS INFORMATION 2.5 RT = 20kΩ VIN VIN LT8619 2.0 EN/UV fSW (MHz) GND 1.5 8619 F10 1.0 Figure 10. Reverse VIN Protection 0.5 0 PCB Layout 0 0.1 0.2 0.3 0.4 0.5 VFB (V) 0.6 0.7 0.8 8619 F08 Figure 8. Frequency Foldback Transfer Function VOUT 1V/DIV ISHORT 10A/DIV IL 0.5A/DIV SW 10V/DIV 5μs/DIV 8619 F09 Figure 9. Short-Circuit Waveform with VIN = 12V, VOUT = 3.3V, fOSC = 2MHz, L = 4.
PAGE 21
LT8619/LT8619-5 APPLICATIONS INFORMATION VOUT SW + GND EN/UV RT PG VIN SYNC BST INTVCC BIAS FB/OUT RT VOUT 8619 F11 Figure 11. Recommended PCB Layout for LT8619 10-Pin DFN VOUT SW + GND EN/UV VIN PG SYNC BST INTVCC BIAS FB/OUT VOUT RT 8619 F12 Figure 12. Recommended PCB Layout for LT8619 16-Pin MSOP Rev A For more information www.analog.com Downloaded from Arrow.com.
PAGE 22
LT8619/LT8619-5 APPLICATIONS INFORMATION For higher ambient temperatures, care should be taken in the layout of the PCB to ensure good heat sinking of the LT8619. The exposed pad on the bottom of the package must be soldered to a ground plane. This ground should be tied to large copper layers below with thermal vias; these layers will spread heat dissipated by the LT8619. Placing additional vias can reduce thermal resistance further. Figure 13 shows the rise in case temperature vs load current.
PAGE 23
LT8619/LT8619-5 TYPICAL APPLICATIONS 3.3V 400kHz Step-Down Converter VIN 4V TO 60V BST VIN 2.2µF OFF ON 0.1µF 15µH VOUT 3.3V 1.2A SW LT8619 100k EN/UV PG 1µF PG BIAS INTVCC 1M SYNC 121k 6.8pF FB RT GND 8619 TA02 22µF 316k fOSC = 400kHz L = VISHAY IHLP-3232CZ-11 COUT = TDK C3225X7R1C226K250 1.8V 2MHz Step-Down Converter VIN 3.3V TO 12V 2.2µF 1µF VIN INTVCC LT8619 OFF ON EN/UV SW PG 0.1µF 2.2µH BIAS 1.87M FB RT 20k PG BST 100k SYNC GND 5.6pF VOUT 1.8V 1.2A 22µF 1.
PAGE 24
LT8619/LT8619-5 TYPICAL APPLICATIONS 5V 2MHz Step-Down Converter VIN 6V TO 36V (60V TRANSIENT) 2.2µF OFF ON VIN BST LT8619-5 0.1µF 4.7µH 100k EN/UV 1µF 20k VOUT 5V 1.2A SW PG PG INTVCC BIAS OUT GND RT SYNC 22µF 8619 TA04 fOSC = 2MHz L = VISHAY IHLP-2020BZ-01 COUT = TDK C3225X7R1C226K250 12V 700kHz Step-Down Converter VIN 13V TO 60V 1µF 2.2µF VIN INTVCC PG BST LT8619 OFF ON EN/UV PG 0.1µF 22µH BIAS RT 66.5k SW 100k 0.931M 22pF FB SYNC GND 8619 TA05 401k VOUT 12V 1.2A 66.
PAGE 25
LT8619/LT8619-5 PACKAGE DESCRIPTION DD Package 10-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1699 Rev C) 0.70 ±0.05 3.55 ±0.05 1.65 ±0.05 2.15 ±0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC 2.38 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 ±0.10 (4 SIDES) R = 0.125 TYP 6 0.40 ±0.10 10 1.65 ±0.10 (2 SIDES) PIN 1 NOTCH R = 0.20 OR 0.35 × 45° CHAMFER PIN 1 TOP MARK (SEE NOTE 6) 0.200 REF 0.75 ±0.05 0.00 – 0.05 5 1 (DD) DFN REV C 0310 0.25 ±0.05 0.
PAGE 26
LT8619/LT8619-5 PACKAGE DESCRIPTION MSE Package 16-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1667 Rev F) BOTTOM VIEW OF EXPOSED PAD OPTION 2.845 ±0.102 (.112 ±.004) 5.10 (.201) MIN 2.845 ±0.102 (.112 ±.004) 0.889 ±0.127 (.035 ±.005) 8 1 1.651 ±0.102 (.065 ±.004) 1.651 ±0.102 3.20 – 3.45 (.065 ±.004) (.126 – .136) 0.305 ±0.038 (.0120 ±.0015) TYP 16 0.50 (.0197) BSC 4.039 ±0.102 (.159 ±.004) (NOTE 3) RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 0.35 REF 0.
PAGE 27
LT8619/LT8619-5 REVISION HISTORY REV DATE DESCRIPTION A 07/18 Clarified SYNC Threshold Units PAGE NUMBER 3 Clarified Efficiency at VOUT = 5V 5 Rev A 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. Specifications subject to change without notice.
PAGE 28
LT8619/LT8619-5 TYPICAL APPLICATION Ultralow EMI 5V 2MHz Step-Down Converter VIN 6V TO 36V (60V TRANSIENT) FB1 BEAD LIN 4.7µH 4.7µF 4.7µF 4.7µF BST VIN 0.1µF 4.7µH LT8619-5 VOUT 5V 1.2A SW OFF ON 1µF PG INTVCC PG BIAS RT SYNC 20k FB1 = TDK MPZ2012S221A LIN = XFL4020 L = VISHAY IHLP-2020BZ-01 COUT = TDK C3225X7R1C226K250 100k EN/UV OUT GND 22µF 8619 TA06 fOSC = 2MHz RELATED PARTS PART DESCRIPTION COMMENTS LT8602 42V, Quad Output (2.5A + 1.5A + 1.5A + 1.5A) 95% Efficiency, 2.