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Evaluation Board User Guide

UG-204

One Technology Way • P. O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Te l: 781.329.4700 • Fax: 781.461.3113 • www.analog.com

Evaluation Board for the ADP1850SP Step-Down DC-to-DC Controller

PLEASE SEE THE LAST PAGE FOR AN IMPORTANT

WARNING AND LEGAL TERMS AND CONDITIONS.

Rev. A | Page 1 of 12

FEATURES

Input range: 10 V to 20 V

Two output voltages: 3.3 V and 1.8 V

Output current: 14 A per channel

Switching frequency: 600 kHz

Operates in PWM or PSM

Compact, low cost, and efficient design

EVALUATION BOARD DESCRIPTION

This document describes the design, operation, and test results

of the ADP1850SP-EVALZ. The input range for this evaluation

board is 10 V to 20 V, and the two regulated output voltages are

set to 3.3 V (V

OUT1

) and 1.8 V (V

OUT2

) with a maximum 14 A

output current. A switching frequency (f

) of 600 kHz is chosen

to achieve a good balance between efficiency and the sizes of

the power components.

ADP1850 DEVICE DESCRIPTION

The ADP1850 is a dual-channel, step-down switching controller

with integrated drivers for external N-channel synchronous

power MOSFETs. The two PWM outputs are phase shifted

180°, which reduces the input RMS ripple current, thus

minimizing required input capacitance. The two outputs can be

combined for dual-phase PWM operation that can deliver more

than 50 A output current. The internal parameters of the two

channels are optimized for current sharing.

In addition, boost diodes are integrated into the ADP1850,

thus lowering the overall system cost and component count.

The ADP1850 can be set to operate in pulse skip, high

efficiency mode under light load or in PWM continuous

conduction mode.

The ADP1850 includes externally adjustable soft start, output

overvoltage protection, externally adjustable current limit,

power good, tracking function, and a programmable oscillator

frequency that ranges from 200 kHz to 1.5 MHz. The ADP1850

provides an output voltage accuracy of ±0.85% from −40°C to

+85°C and ±1.5% from −40°C to +125°C junction temperature.

This controller can be powered from a 2.75 V to 20 V supply

and is available in a 32-lead 5 mm × 5 mm LFCSP package.

ADP1850SP EVALUATION BOARD

09455-001

VIN TERMINALGND TERMINAL

DP1850

GND TERMINAL

VOUT1 TERMINAL

VOUT2 TERMINAL

Figure 1.

Summary of content (12 pages)

PAGE 1
Evaluation Board User Guide UG-204 One Technology Way • P.O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel: 781.329.4700 • Fax: 781.461.3113 • www.analog.com Evaluation Board for the ADP1850SP Step-Down DC-to-DC Controller power MOSFETs. The two PWM outputs are phase shifted 180°, which reduces the input RMS ripple current, thus minimizing required input capacitance. The two outputs can be combined for dual-phase PWM operation that can deliver more than 50 A output current.
PAGE 2
UG-204 Evaluation Board User Guide TABLE OF CONTENTS Features .............................................................................................. 1 Output Capacitors .........................................................................3 Evaluation Board Description......................................................... 1 MOSFET Selection........................................................................3 ADP1850 Device Description..................................................
PAGE 3
Evaluation Board User Guide UG-204 COMPONENT DESIGN For information about selecting power components and calculating component values, see the ADP1850 data sheet. OUTPUT CAPACITORS A 1.2 μH inductor with a 20 A average current rating (744325120 from Würth Elektronik) is selected. This is a compact inductor with a ferrite core, which offers high performance in terms of low RDC and low core loss. A combination of POSCAP™ polymer capacitors and MLCCs are selected for the output rails.
PAGE 4
UG-204 Evaluation Board User Guide TEST RESULTS TA = 25°C. 100 SW1 90 80 1 VOUT1 RIPPLE 60 2 VIN = 12V, FREQUENCY = 600kHz 50 SW2 40 3 30 VOUT1 = 3.3V VOUT2 = 1.8V VOUT1_1.8V_PWM VOUT1_1.8V_PSM 10 0 0.01 0.1 1 10 4 VOUT2 RIPPLE 100 LOAD (A) 09455-002 20 CH1 10V CH3 10V CH2 20mV CH4 20mV M1µs A CH1 12.8V 09455-005 EFFICIENCY (%) 70 Figure 5. Output Ripple, 14 A Load Figure 2. Efficiency (Measurement Is Made with the Adjacent Channel Disabled) 0.
PAGE 5
Evaluation Board User Guide UG-204 EVALUATION BOARD OPERATING INSTRUCTION 1. 2. 3. Connect Jumper J3 (EN1) to the high position to enable Channel 1 of the ADP1850. Connect Jumper J2 (EN2) to the high position to enable Channel 2 of the ADP1850. Connect Jumper J4 (FREQ) to the high position for 600 kHz operation. 4. 5. Connect Jumper J1 (SYNC) to the high position for PWM operation or to low for PSM operation. Connect the positive terminal of the input power supply to the input terminal, T1.
PAGE 6
UG-204 Evaluation Board User Guide OTHER INFORMATION ABOUT THE EVALUATION BOARD PCB LAYOUT As seen in Figure 1, the layout of this evaluation board is not optimized for the smallest PCB area. It is laid out in such a way that any of the components can be desoldered and replaced easily with different components with a hand soldering iron so that the user can modify the existing design without acquiring a new PCB layout.
PAGE 7
1 1 2 3 4 1 VDL 1 2 3 4 1 VDL TP16 TURRET T11 T2 TURRET T10 T1 VIN VIN 2 RB0 open RFREQ 100nf CVIN 1 J1 VCC 2 Vin = 10V to 20V 1 1 TP3 J4 SYNC 3 2 Way Link VCC FB1 J2 J3 VCC 2 Way Link 3 RT22 open RT24 RT21 0 TP5 REN21 REN22 RT23 TRK2 open VOUT1 187k RR2 23.2k 10k RF22 560pF RC2 CC21 EN2 FREQ AGND VDL VCCO VIN SYNC EN1 47pF 8 7 6 5 4 3 2 1 42.2k U1 330pF 47pF RC1 CC11 CC12 187k COMP1 RR1 10K CC22 1.0uF 1.
PAGE 8
Evaluation Board User Guide 09455-009 UG-204 09455-010 Figure 9. Top Silkscreen Figure 10. Top Layer Rev.
PAGE 9
UG-204 09455-011 Evaluation Board User Guide 09455-012 Figure 11. Second Layer (AGND Plane) Figure 12. Third Layer (PGND Layer) Rev.
PAGE 10
Evaluation Board User Guide 09455-013 UG-204 09455-014 Figure 13. Bottom Layer (PGND Layer) Figure 14. Bottom Silk Screen Rev.
PAGE 11
Evaluation Board User Guide UG-204 ORDERING INFORMATION BILL OF MATERIALS Table 3. Qty 1 1 4 Reference Designator U1 CIN20 CIN11, CIN12, CIN21, CIN22 Manufacturer Analog Devices Sanyo Murata Part No.
PAGE 12
UG-204 Evaluation Board User Guide NOTES ESD Caution ESD (electrostatic discharge) sensitive device. Charged devices and circuit boards can discharge without detection. Although this product features patented or proprietary protection circuitry, damage may occur on devices subjected to high energy ESD. Therefore, proper ESD precautions should be taken to avoid performance degradation or loss of functionality.