ANALOG DEVICES UG-431 Service Manual

ADP1853-EVALZ User Guide

UG-431

ADP1853 VIN+ TERMINAL GND TERMI NAL

VOUT+ TE RM INAL

10831-001

One Technology Way P. O. Box 9106 Norwood, MA 02062-9106, U.S.A. Tel: [phone] Fax: [phone] www.analog.com

Evaluation Board for the ADP1853 Step-Down DC-to-DC Controller

FEATURES

Input voltage range: 9 V to 15 V
Output voltage: 3.3 V
Output current: up to 20 A
Switching frequency: 300 kHz
Operates in PWM or PSM
Designed for evaluation of the ADP1853 functionality
Flexible and easy to re-configure and modify

EVALUATION BOARD DESCRIPTION

This document describes the design, operation, and test
results of the ADP1853-EVAL Z. The input voltage range for
this evaluation board is 9 V to 15 V, an d t h e regulated output
voltage V
up to 20 A. The switching frequency (f
achieve high efficiency.

is set to 3.3 V with the maximum output current

OUT

) of 300 kHz is set to

SW

ADP1853 DEVICE DESCRIPTION

The ADP1853 is a step-down switching controller with inte­grated drivers for N-channel synchronous power MOSFETs.
The switching frequency of the ADP1853 can be synchronized
to an external clock signal applied to the SYNC input. The

ADP1853 has a clock output, CLKOUT, which can be used

for synchronizing other controllers. The CLKOUT frequency
is the same as the switching and it is 180° out of phase.

In addition, the boost diode is integrated into the ADP1853,
thus lowering the overall system cost and component count.
The ADP1853 can be set to operate in pulse skip, high effi-
ciency mode (PSM) under light load, or in PWM continuous
conduction mode.

The ADP1853 includes externally adjustable soft start, output
overvoltage protection, externally programmable current limit,
power good, tracking function, and a programmable oscillator
frequency that ranges from 200 kHz to 1.5 MHz. The ADP1853
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 20-lead 4 mm ×
4 mm LFCSP package.

ADP1853 EVALUATION BOARD

Figure 1.

PLEASE SEE THE LAST PAGE FOR AN IMPORTANT
WARNING AND LEGAL TERMS AND CONDITIONS.

Rev. 0 | Page 1 of 12

UG-431 ADP1853-EVALZ User Guide

TABLE OF CONTENTS

Features .............................................................................................. 1

Evaluation Board Description......................................................... 1

ADP1853 Device Description ......................................................... 1

ADP1853 Evaluation Board ............................................................ 1

Revision History ............................................................................... 2

Component Design .......................................................................... 3

ADIsimPower Design Tool ......................................................... 3

Inductor Selection ........................................................................ 3

Input Capacitors ........................................................................... 3

REVISION HISTORY

6/12—Revision 0: Initial Version

Output Capacitors .........................................................................3

MOSFET Selection ........................................................................3

Test Results .........................................................................................4

Evaluation Board Operating Instruction .......................................5

Other Information About the Evaluation Board PCB Layout .... 6

Evaluation Board Schematics and Artwork ...................................7

Ordering Information .................................................................... 10

Bill of Materials ........................................................................... 10

Rev. 0 | Page 2 of 12

ADP1853-EVALZ User Guide UG-431

COMPONENT DESIGN

ADIsimPower DESIGN TOOL

The ADP1853 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. ADIsimPower can optimize
designs for cost, area, efficiency, and parts count while taking
into consideration the operating conditions and limitations of
the IC and all real external components. The ADIsimPower
tool can be found at www.analog.com/ADIsimPower and the
user can request an unpopulated board through the tool.

For information about selecting power components and calcu­lating component values, see also the ADP1853 data sheet.

INDUCTOR SELECTION

The selected inductor is a Coilcraft SER1412-102ME with 1 µH
inductance, and 32 A saturation current. This shielded inductor
with a flat wire windings core provides exceptionally low DCR
of 1.3 mΩ (typical).

INPUT CAPACITORS

Because of the low ESR and high input current rating of a multi­layer ceramic capacitor (MLCC), a 10 µF MLCC is selected as
the input capacitor close to the high-side power MOSFET. In
addition, a 150 µF bulk OS-CON™ capacitor (aluminum solid
capacitor with conductive polymer) from Sanyo is chosen for
filtering out any unwanted low frequency noise from the input
power supply.

OUTPUT CAPACITORS

A combination of a 330 µF POSCAP™ polymer capacitor and a
22 µF MLCC is selected for the output rail. Polymer capacitors
have low ESR and high current ripple rating. Connecting poly­mer capacitors and MLCCs in parallel is very effective in
reducing voltage ripple.

MOSFET SELECTION

For low output or low duty cycle, select a high-side MOSFET
with fast rise and fall times and with low input capacitance
to minimize charging and switching power loss. As for the
synchronous rectifier (low-side MOSFET), select a MOSFET
with low R
during the switching cycle and contributes larger portion in
the conductive losses than the high-side MOSFET. For the
high-side MOSFET, the BSC052N03LS from Infineon in the
PG-TDSON-8 package is selected. This part has low input
capacitance (770 pF typical) and fast transition times (typical
turn-on delay is 2.4 ns). For the low-side MOSFET, the BSC090NS
from Infineon, with the R

4.5 V) is selected.

because it conducts current most of the time

DSON

of 3.5 mΩ (maximum at VGS of

DSON

Rev. 0 | Page 3 of 12

UG-431 ADP1853-EVALZ User Guide

100

EFFICIENCY (%)

0.05

–0.05

9 10 11 15141312

LINE REGULATION (%)

INPUT VOLTAGE (V)

–0.04

–0.03

–0.02

–0.01

0

0.01

0.02

0.03

0.04

10831-003

0.4

0.2

–0.6

–0.4

–0.2

0 10 155 20

LOAD REGULATION (%)

LOAD CURRENT ( A)

0

10831-004

CH1 5V

B

W

CH3 10V

B

W

CH2 100mV

B

W

CH4 5V

B

W

M10µs
A CH4 2.6V

625MS/s 1.6ns/pt

3

1

2

4

DH

DL

VOUT_AC

CLKOUT

10831-005

CH1 5V

B

W

CH3 10V

B

W

CH2 200mV

B

W

CH4 5V

B

W

M2µs
A CH1 2.9V

1.25GS/s IT 40.0ps/pt

3

1

2

4

SW

CLKOUT

VOUT_AC

SYNC

10831-006

CH2 200mV

B

W

CH4 5A Ω

B

W

M100µs
A CH4 14.4A

125MS/s 8.0ns/pt

2

4

VOUT_AC

LOAD CURRENT

10831-007

TEST RESULTS

TA = 25°C.

90

80

70

60

50

40

30

20

10

0

0.1 101 100

Figure 2. Efficiency, VIN = 12 V, V

LOAD (A)

= 3.3 V, f

OUT

PULSE SKIP
FORCED PW M

= 300 kHz

OSC

10831-002

Figure 5. Switching Waveforms, Light Load of 0.5 A,

f

= 300 kHz, Pulse Skip Enabled, SYNC Low

OSC

Figure 3. Line Regulation, V

Figure 4. Load Regulation, V

= 3.3 V, fSW = 300 kHz, 20 A Load

OUT

= 12 V, V

IN

= 3.3 V, fSW = 300 kHz

OUT

Rev. 0 | Page 4 of 12

Figure 6. Switching Waveforms, 20 A Load, f

Figure 7. V

Transient Response, 20 A to 10 A Load Step

OUT

= 300 kHz

SYNC