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20 V, 6 A, Synchronous Step-Down

DC-to-DC Regulator

Data Sheet

ADP2386

Rev. A Document Feedback

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FEATURES

Input voltage: 4.5 V to 20 V

Integrated MOSFET: 44 mΩ/11 mΩ

Reference voltage: 0.6 V ± 1%

Continuous output current: 6 A

Programmable switching frequency: 200 kHz to 1.4 MHz

Synchronizes to external clock: 200 kHz to 1.4 MHz

180° out of phase clock synchronization

Precision enable and power good

External compensation

Internal soft start with external adjustable option

Startup into a precharged output

Supported by ADIsimPower design tool

APPLICATIONS

Communications infrastructure

Networking and servers

Industrial and instrumentation

Healthcare and medical

Intermediate power rail conversion

DC-to-dc point-of-load applications

TYPICAL APPLICATIONS CIRCUIT

ADP2386

BST

COMP

PGOOD

GND

VREG

SYNC

VREG

PGND

PVIN

BST

OUT

TOP

BOT

10211-001

Figure 1.

100

0 1 2 3 4 5 6

EFFICIENCY (%)

OUTPUT CURRENT (A)

OUT

= 5.0V

OUT

= 3.3V

OUT

= 1.2V

10211-002

Figure 2. Efficiency vs. Output Current, V

= 12 V, f

= 300 kHz

GENERAL DESCRIPTION

The ADP2386 is a synchronous step-down, dc-to-dc regulator with

an integrated 44 mΩ, high-side power MOSFET and an 11 mΩ,

synchronous rectifier MOSFET to provide a high efficiency

solution in a compact 4 mm × 4 mm LFCSP package. This device

uses a peak current mode, constant frequency pulse-width

modulation (PWM) control scheme for excellent stability and

transient response. The switching frequency of the ADP2386

can be programmed from 200 kHz to 1.4 MHz. To minimize

system noise, the synchronization function allows the switching

frequency to be synchronized to an external clock.

The ADP2386 requires minimal external components and

operates from an input voltage of 4.5 V to 20 V. The output

voltage can be adjusted from 0.6 V to 90% of the input voltage

and delivers up to 6 A of continuous current. Each IC draws less

than 110 μA current from the input source when it is disabled.

This regulator targets high performance applications that require

high efficiency and design flexibility. External compensation and an

adjustable soft start function provide design flexibility. The power-

good output and precision enable input provide simple and reliable

power sequencing.

Other key features include undervoltage lockout (UVLO),

overvoltage protection (OVP), overcurrent protection (OCP),

short-circuit protection (SCP), and thermal shutdown (TSD).

The ADP2386 operates over the −40°C to +125°C junction

temperature range and is available in a 24-lead, 4 mm × 4 mm

LFCSP package.

Summary of content (24 pages)

PAGE 1
20 V, 6 A, Synchronous Step-Down DC-to-DC Regulator ADP2386 Data Sheet FEATURES TYPICAL APPLICATIONS CIRCUIT ADP2386 VIN BST PVIN CIN CBST EN VOUT PGOOD COUT RTOP SYNC FB RT RT L SW COMP VREG CVREG SS GND PGND RC RBOT CC CSS 10211-001 Input voltage: 4.5 V to 20 V Integrated MOSFET: 44 mΩ/11 mΩ Reference voltage: 0.6 V ± 1% Continuous output current: 6 A Programmable switching frequency: 200 kHz to 1.4 MHz Synchronizes to external clock: 200 kHz to 1.
PAGE 2
ADP2386 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Thermal Shutdown .................................................................... 14 Applications ....................................................................................... 1 Applications Information .............................................................. 15 Typical Applications Circuit....................................................
PAGE 3
Data Sheet ADP2386 SPECIFICATIONS VPVIN = 12 V, TJ = −40°C to +125°C for minimum/maximum specifications, and TA = 25°C for typical specifications, unless otherwise noted. Table 1.
PAGE 4
ADP2386 Parameter PGOOD Power-Good Range FB Rising Threshold FB Rising Hysteresis FB Falling Threshold FB Falling Hysteresis Power-Good Deglitch Time Power-Good Leakage Current Power-Good Output Low Voltage EN EN Rising Threshold EN Falling Threshold EN Source Current Data Sheet Symbol Test Conditions/Comments PGOOD from low to high PGOOD from high to low PGOOD from low to high PGOOD from high to low PGOOD from low to high PGOOD from high to low VPGOOD = 5 V IPGOOD = 1 mA EN voltage below falling thresh
PAGE 5
Data Sheet ADP2386 ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE Table 2. Parameter PVIN, EN, PGOOD SW BST FB, SS, COMP, SYNC, RT VREG PGND to GND Operating Junction Temperature Range Storage Temperature Range Soldering Conditions Rating −0.3 V to +22 V −1 V to +22 V VSW + 6 V −0.3 V to +6 V −0.3 V to +12 V −0.3 V to +0.
PAGE 6
ADP2386 Data Sheet 20 EN 19 PVIN 22 RT 21 PGOOD 24 SS 23 SYNC PIN CONFIGURATION AND FUNCTION DESCRIPTIONS 18 PVIN COMP 1 FB 2 17 PVIN 25 GND VREG 3 16 PVIN 15 BST GND 4 26 SW SW 5 14 SW SW 6 PGND 12 PGND 11 PGND 9 PGND 10 SW 7 PGND 8 13 PGND TOP VIEW NOTES 1. THE EXPOSED GND PAD MUST BE SOLDERED TO A LARGE, EXTERNAL, COPPER GND PLANE TO REDUCE THERMAL RESISTANCE. 2.
PAGE 7
Data Sheet ADP2386 TYPICAL PERFORMANCE CHARACTERISTICS 100 100 95 95 90 90 85 85 EFFICIENCY (%) 80 75 70 65 75 70 65 0 1 55 5 4 3 2 VOUT = 1.2V VOUT = 1.8V VOUT = 2.5V VOUT = 3.3V VOUT = 5V 60 6 OUTPUT CURRENT (A) 50 10211-007 55 0 100 100 95 95 90 90 85 85 EFFICIENCY (%) 4 5 6 80 75 70 80 75 70 65 60 1 0 2 3 4 5 55 6 OUTPUT CURRENT (A) 50 10211-005 55 VOUT = 1.0V VOUT = 1.2V VOUT = 1.5V VOUT = 1.8V VOUT = 2.5V VOUT = 3.3V 60 VOUT = 1.8V VOUT = 2.
PAGE 8
ADP2386 4.5 4.4 Data Sheet 1.25 RISING FALLING RISING FALLING EN THRESHOLD (V) PVIN UVLO THRESHOLD (V) 1.20 4.3 4.2 4.1 4.0 3.9 1.15 1.10 1.05 3.8 1.00 –20 0 20 40 60 80 100 120 TEMPERATURE (°C) 0.95 –40 10211-010 3.6 –40 –20 0 20 40 60 80 100 120 TEMPERATURE (°C) 10211-013 3.7 Figure 13. EN Threshold vs. Temperature Figure 10. PVIN UVLO Threshold vs. Temperature 606 3.30 3.25 FEEDBACK VOLTAGE (mV) SS PULL-UP CURRENT (μA) 604 3.20 3.15 3.10 3.05 3.
PAGE 9
Data Sheet 10.5 MOSFET RESISTOR (mΩ) 55 45 35 25 5 –40 –20 20 0 40 60 80 100 120 TEMPERATURE (°C) 9.5 9.0 8.5 8.0 7.5 –40 10211-016 15 10.0 –20 0 20 40 60 80 100 120 TEMPERATURE (°C) Figure 16. MOSFET RDSON vs. Temperature Figure 19. Current-Limit Threshold vs. Temperature VOUT (AC) 1 EN 3 IL VOUT 1 2 SW PGOOD 3 IOUT 2 B W CH2 10V M2.00µs T 50.2% A CH2 6V CH1 2V CH3 10V Figure 17. Working Mode Waveform B CH2 5V CH4 5A Ω W M2.00ms T 50% A CH2 5.
PAGE 10
ADP2386 Data Sheet VOUT (AC) VOUT (AC) 1 1 VIN SW 3 IOUT B W CH4 2A Ω M200µs T 70.4% A CH4 2.8A 10211-022 CH1 100mV B CH1 20mV CH3 5V B W CH2 10V W B W M1.00ms T 20% A CH3 12.4V 10211-025 2 4 Figure 25. Line Transient Response, VIN from 8 V to 14 V, IOUT = 6 A Figure 22. Load Transient Response, 1 A to 5 A VOUT VOUT 1 1 SW SW 2 2 IL IL 4 W CH2 10V CH4 5A Ω M4.00ms T 30.2% A CH1 2.12V CH1 2V 6 6 5 5 LOAD CURRENT (A) 7 4 3 2 VOUT = 1.2V VOUT = 1.
PAGE 11
Data Sheet ADP2386 FUNCTIONAL BLOCK DIAGRAM VREG CLK RT OSC BIAS AND DRIVER REGULATOR PVIN SLOPE RAMP SYNC UVLO EN EN_BUF BOOST REGULATOR 1.17V 1µA 4µA ACS SLOPE RAMP Σ VI_MAX + OCP – HICCUP MODE BST COMP 0.6V + SS + AMP FB – DRIVER SW CONTROL LOGIC AND MOSFET DRIVER WITH ANTICROSS PROTECTION OVP 0.7V NFET + CMP – ISS NFET DRIVER CLK PGND – NEG CURRENT – CMP + + – 0.54V VREG VI_NEG + PGOOD DEGLITCH 10211-028 GND Figure 28. Rev.
PAGE 12
ADP2386 Data Sheet THEORY OF OPERATION The ADP2386 operates from an input voltage that ranges from 4.5 V to 20 V and regulates the output voltage from 0.6 V to 90% of the input voltage. Additional features that maximize design flexibility include the following: programmable switching frequency, programmable soft start, external compensation, precision enable, and a power-good output. BOOTSTRAP CIRCUITRY The ADP2386 includes a regulator to provide the gate drive voltage for the high-side N-MOSFET.
PAGE 13
Data Sheet ADP2386 VOUT RISING SOFT START 105% 100% 95% 90% 1600 (ms) f SW (kHz) A slower soft start time can be programmed by using the SS pin. When a capacitor is connected between the SS pin and GND, an internal current charges the capacitor to establish the soft start ramp. The soft start time is calculated using the following equation: tSS_EXT = 0.6 V  C SS I SS _ UP where: CSS is the soft start capacitance. ISS_UP is the soft start pull-up current (3.2 μA).
PAGE 14
ADP2386 Data Sheet OVERVOLTAGE PROTECTION (OVP) The ADP2386 includes an overvoltage protection feature to protect the regulator against an output short to a higher voltage supply or when a strong load disconnect transient occurs. If the feedback voltage increases to 0.7 V, the internal high-side and low-side MOSFETs are turned off until the voltage at the FB pin decreases to 0.63 V. At that time, the ADP2386 resumes normal operation.
PAGE 15
Data Sheet ADP2386 APPLICATIONS INFORMATION INPUT CAPACITOR SELECTION The input capacitor reduces the input voltage ripple caused by the switch current on PVIN. Place the input capacitor as close as possible to the PVIN pin. A ceramic capacitor in the 10 μF to 47 μF range is recommended. The loop that is composed of this input capacitor, the high-side N-MOSFET, and the low-side NMOSFET must be kept as small as possible.
PAGE 16
ADP2386 Data Sheet For a duty cycle that is larger than 50%, the minimum inductor value is determined using the following equation: L (Minimum) = VOUT × (1 − D ) 2 × f SW Another example occurs when a load is suddenly removed from the output, and the energy stored in the inductor rushes into the output capacitor, causing the output to overshoot. The peak inductor current is calculated by IPEAK = IOUT + ∆I L 2 The saturation current of the inductor must be larger than the peak inductor current.
PAGE 17
Data Sheet ADP2386 The selected output capacitor voltage rating must be greater than the output voltage. The rms current rating of the output capacitor must be larger than the value that is calculated by using the following equation: ICOUT_RMS = ∆I L 12 The ADP2386 uses a transconductance amplifier for the error amplifier and to compensate the system. Figure 32 shows the simplified, peak current-mode control, small signal circuit.
PAGE 18
ADP2386 Data Sheet DESIGN EXAMPLE VIN = 12V PVIN BST CBST 0.1µF EN L1 2.2µF PGOOD SYNC RT 100kΩ CVREG 1µF RTOP 10kΩ 1% ADP2386 RT FB COMP VREG CSS 22nF VOUT = 3.3V SW SS CCP 4.7pF GND PGND RC 44.2kΩ CC 1.2nF COUT1 100µ F 6.3V COUT2 47µ F 6.3V RTOP 2.21kΩ 1% 10211-033 CIN 10µF 25V Figure 33. Schematic for Design Example This section describes the procedures for selecting the external components, based on the example specifications that are listed in Table 8.
PAGE 19
Data Sheet ADP2386 OUTPUT CAPACITOR SELECTION The output capacitor is required to meet both the output voltage ripple and load transient response requirements. The 100 µF and 47 µF ceramic output capacitors have a derated value of 62 µF and 32 µF. RC = 2 × π × 3.3V × 94 μF × 60 kHz = 46.7 kΩ 0.6 V × 480 μs × 8.7 A/ V To meet the output voltage ripple requirement, use the following equation to calculate the ESR and capacitance value of the output capacitor: CCP = 0.002 Ω × 94 μF = 4.0 pF 46.
PAGE 20
ADP2386 Data Sheet RECOMMENDED EXTERNAL COMPONENTS Table 9. Recommended External Components for Typical Applications with 6 A Output Current fSW (kHz) 300 600 1000 1 VIN (V) 12 12 12 12 12 12 12 5 5 5 5 5 5 12 12 12 12 12 5 5 5 5 5 5 12 12 12 5 5 5 5 5 5 VOUT (V) 1 1.2 1.5 1.8 2.5 3.3 5 1 1.2 1.5 1.8 2.5 3.3 1.5 1.8 2.5 3.3 5 1 1.2 1.5 1.8 2.5 3.3 2.5 3.3 5 1 1.2 1.5 1.8 2.5 3.3 L (µH) 1.5 2.2 2.2 3.3 3.3 4.7 4.7 1.5 1.5 2.2 2.2 2.2 2.2 1 1.5 2.2 2.2 3.3 1 1 1 1 1 1 1 1.5 1.5 0.47 0.47 0.68 0.68 0.
PAGE 21
Data Sheet ADP2386 CIRCUIT BOARD LAYOUT RECOMMENDATIONS Good printed circuit board (PCB) layout is essential for obtaining the best performance from the ADP2386. Poor PCB layout can degrade the output regulation, as well as the electromagnetic interference (EMI) and electromagnetic compatibility (EMC) performance. Figure 36 shows an example of a good PCB layout for the ADP2386.
PAGE 22
ADP2386 Data Sheet TYPICAL APPLICATIONS CIRCUITS BST PVIN CIN 10µF 25V CBST L1 0.1µF 1µH EN PGOOD SYNC RT 124kΩ RTOP 10kΩ 1% ADP2386 COUT1 470µF 6.3V COUT2 10µF 6.3V FB RT VREG CVREG 1µF VOUT = 1.2V SW COMP SS CCP 68pF GND PGND CSS 22nF RC 66.5kΩ CC 1.5nF RBOT 10kΩ 1% 10211-035 VIN = 12V Figure 37. Typical Applications Circuit, VIN = 12 V, VOUT = 1.2 V, IOUT = 6 A, fSW = 500 kHz VIN = 12V PVIN CIN 10µF 25V BST EN CBST 0.1µF PGOOD L1 1.
PAGE 23
Data Sheet ADP2386 OUTLINE DIMENSIONS PIN 1 INDICATOR 0.20 MIN 0.20 MIN 2.80 2.70 2.60 0.20 MIN 19 24 18 1 EXPOSED PAD 0.50 BSC 0.35 0.25 EXPOSED PAD 0.80 0.75 0.70 SEATING PLANE 0.50 0.40 0.30 12 7 BOTTOM VIEW 0.05 MAX 0.02 NOM COPLANARITY 0.08 0.203 REF 0.25 0.20 0.15 1.05 0.95 0.85 6 13 TOP VIEW PIN 1 INDICATOR 1.50 1.40 1.30 0.45 0.20 MIN FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET.