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ADP1851-EVALZ User Guide

UG-443

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 ADP1851 Step-Down DC-to-DC Controller

PLEASE SEE THE LAST PAGE FOR AN IMPORTANT

WARNING AND LEGAL TERMS AND CONDITIONS.

Rev. 0 | Page 1 of 12

FEATURES

Input voltage range: 9 V to 15 V

Output voltage: 1.8 V

Output current: up to 25 A

Switching frequency: 600 kHz

Operates in PWM or PSM

Designed for evaluation of the ADP1851 functionality

Flexible and easy to re-configure and modify

EVALUATION BOARD DESCRIPTION

This document describes the design, operation, and test results

of the ADP1851-EVA L Z . The input voltage range for this eval-

uation board is 9 V to 15 V, an d t h e regulated output voltage

OUT

) is set to 1.8 V with the maximum output current up to

25 A. The switching frequency (f

) of 600 kHz is set to achieve

high efficiency. The switching frequency can be also synchro-

nized to an external clock signal applied to the SYNC input.

ADP1851 DEVICE DESCRIPTION

The ADP1851 is a step-down switching controller with inte-

grated drivers for N-channel synchronous power MOSFETs.

The ADP1851 can be set to operate in pulse skip mode (PSM)

for high efficiency under light load, or in PWM continuous

conduction mode. In addition, the boost diode is integrated

into the ADP1851, thus lowering the overall system cost and

component count.

The ADP1851 includes externally adjustable soft start, output

overvoltage protection, externally programmable current limit,

power good output, and a programmable oscillator frequency

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

of the ADP1851 can be synchronized to an external clock signal

applied to the SYNC input. The ADP1851 has the reference

voltage accuracy of ±1% 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 16-lead 4 mm × 4 mm

LFCSP package.

ADP1851 EVALUATION BOARD

Figure 1.

ADP1851

VIN+ TERMINAL GND TERMINAL

VOUT+ TERMINAL

10909-001

Summary of content (12 pages)

PAGE 1
ADP1851-EVALZ User Guide UG-443 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 ADP1851 Step-Down DC-to-DC Controller FEATURES ADP1851 DEVICE DESCRIPTION Input voltage range: 9 V to 15 V Output voltage: 1.
PAGE 2
UG-443 ADP1851-EVALZ User Guide TABLE OF CONTENTS Features .............................................................................................. 1 Output Capacitors .........................................................................3 Evaluation Board Description......................................................... 1 MOSFET Selection ........................................................................3 ADP1851 Device Description ...................................................
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ADP1851-EVALZ User Guide UG-443 COMPONENT DESIGN ADIsimPower DESIGN TOOL OUTPUT CAPACITORS The ADP1851 is supported by the ADIsimPower™ design tool set. ADIsimPower is a collection of tools that produce complete power designs optimized to a specific design goal. The tools allow the user to generate a full schematic, bill of materials, and calculate performance in minutes.
PAGE 4
UG-443 ADP1851-EVALZ User Guide TEST RESULTS TA = 25°C. 100 DH 90 80 3 EFFICIENCY (%) 70 DL 60 1 50 40 30 VOUT_AC 20 2 10 1 10 100 LOAD (A) CH1 5V BW CH2 50mV CH3 10V BW B W M4µs 1.25GS/s A CH3 13.4V IT 40ps/pt 10909-005 0 0.1 10909-002 PULSE SKIP FORCED PWM Figure 5. Switching Waveforms, Light Load of 1.5 A, fOSC = 600 kHz, Pulse Skip Enabled, SYNC Low Figure 2. Efficiency, VIN = 12 V, VOUT = 1.8 V, fOSC = 600 kHz 0.08 SYNC 0.06 0.04 DH 0.02 3 0 DL –0.02 1 –0.
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ADP1851-EVALZ User Guide UG-443 EVALUATION BOARD OPERATING INSTRUCTION 1. 2. 3. Connect Jumper JP2 (EN) with a shunt to the low position (disabled). Connect Jumper JP1 (FRQ) with a shunt to the high position for 600 kHz operation. Connect Jumper JP5 (SYNC) with a shunt to the high position for PWM operation or to the low position for pulse skip operation at light load. 4. 5. 6. Remove Jumper JP4 (TRK) for the soft-start operation.
PAGE 6
UG-443 ADP1851-EVALZ 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 by using a hand soldering iron so that the user can modify the existing design without acquiring a new PCB layout.
PAGE 7
T4 1 1 2 3 4 VOUT+ TURRET T3 TURRET 1 C1 150uF/20V TP8 20 R14 T9 TURRET + T10 TURRET 1 T2 1 VIN+ NP C8 NP 4.99K R18 R13 TRK_IN R21 2.49K TP18 1 TP6 R9 NP R8 NP 1 R15 3 21K C10 2 JP4 CON2 JP2 2 Way Link 75pF C9 1 2 620pF VCC NP R5 R3 NP TP2 TP5 1 2 TP16 1 2 SYNC TP12 4 3 2 1 COMP FB SS/TRK EN R1 NP JP1 2 Way Link SS/TRK EN 3 COMP C6 0.1UF R10 0 JP5 2 Way Link 1 1 2 3 4 1 VIN+ R6 140K T1 1 16 FREQ 15 RAMP Vin = 9V to 12V 3 1 1.
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ADP1851-EVALZ User Guide 10909-009 UG-443 10909-010 Figure 9. Top Layer with Silkscreen Figure 10. Second Layer (AGND Plane) Rev.
PAGE 9
UG-443 10909-011 ADP1851-EVALZ User Guide 10909-012 Figure 11. Third Layer (VIN, VCCO, VOUT, and PGND) Figure 12. Bottom Layer Rev.
PAGE 10
UG-443 ADP1851-EVALZ User Guide ORDERING INFORMATION BILL OF MATERIALS Table 3.
PAGE 11
ADP1851-EVALZ User Guide UG-443 NOTES Rev.
PAGE 12
UG-443 ADP1851-EVALZ 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.