Evaluation Board Overview; Power Board And Power Train Overview; Adp1055 Daughter Card; Auxilary Power Board Circuit - Analog Devices ADP1055-EVALZ User Manual

ADP1055-EVALZ User Guide

EVALUATION BOARD OVERVIEW

This ADP1055-EVALZ evaluation board and
EVALZ daughter card feature the
switching power supply in full bridge topology with
synchronous rectification operating at 125 kHz switching
frequency.
Figure 4 shows the block diagram of the evaluation board. The
circuit is designed to provide a rated load of 12 V, 20 A from a
dc input voltage source of 38 V dc to 60 V dc. The
provides functions, including output voltage regulation,
synchronization, constant current control, pre-bias start up,
and comprehensive protection functions.
The evaluation kit consists of a power board, daughter card, and
the auxiliary circuit board.

POWER BOARD AND POWER TRAIN OVERVIEW

The power board is shown in Figure 1. Referring to the
Schematics and Artwork section, the circuit components are
described as follows. The primary and secondary H bridges are
formed with MOSFETs QA through QD (primary side) and
MOSFETs Q30, Q34, Q38, and Q40 (secondary side).
Transformer T2 provides the isolation. The output filter consists
of L8 and a capacitor bank (C48, C49, C51, C70, C73, and C74).
This is the main power stage. The active snubber is made up of
clamp capacitor C192, MOSFET Q23 (pMOS), and driver U19.
Additional circuitry around the power train is described as
follows. The input filter consists of a single state LC (L10 and
C6-13). Components U2 and U5 are half bridge 4 A drivers
based on the Analog Devices, Inc., iCoupler technology that
provides gate drive for driving the primary H bridge. Secondary
side H bridge drivers consist of U20 and U21.
38V TO 60V DC
ADP1055DC1-
ADP1055 in a dc-to-dc
ADP1055
FULL BRIDGE
ADuM3223
iCoupler
+DRIVER
VDD_PRI = 9V
AUXILLARY PSU
PRIMARY = +9V
SECONDARY1 = +9V
SECONDARY2 = +5V
Figure 4. ADP1055-EVALZ
Rev. B | Page 3 of 43
The primary current is sensed using a current transformer T1
that provides primary fast and accurate over current protection
whereas the secondary side current (that is, the load current) is
sensed using a sense resistor (R5, R9).
ADP1055 DAUGHTER CARD
The daughter card is shown in Figure 2. The
card consists of a 3.3 V LDO that powers the
PWMs for the primary switches (OUTA to OUTD) and for the
secondary switches (SR1 and SR2) are connected from the
daughter board to the power board
Figure 2.

AUXILARY POWER BOARD CIRCUIT

The auxiliary power board, included in the kit, is shown in
Figure 3. The auxiliary power circuit provides 9 V on the
primary side and 9 V and 5 V (derived using a Zener diode)
on the secondary side. The approximate minimum operating
voltage of the auxiliary power board is 30 V.
SYNC 12V, 20A
RECTIFIER
MOSFET
ADP1055
DRIVERS
DAUGHTER CARD SOCKET
SR1
AND
3.3V LDO
SR2
OUTA
TO
OUTD
5V
VDD_SEC = 9V
Evaluation Board Block Diagram
ADP1055
ADP1055
ADP1055 Mounted on Daughter Card
Figure 3. Auxiliary Power Board
2
I C INTERFACE
5V FROM USB
OR
UG-710
daughter
IC. The