EVBUM2356/D
NCP1034 Buck Converter
Evaluation Board User's
Manual
www.onsemi.com
EVAL BOARD USER’S MANUAL
Table 1. GENERAL PARAMETERS
Device
NCP1034
Input Voltage
48 V
±20%
Output Voltage
5V
Output Current
5A
Voltage Ripple
< 30 mV
Topology
Buck
I/O Isolation
None
Description
Key Features
This evaluation board user’s manual describes high voltage, high
power and high efficiency DC/DC buck converter featuring the
NCP1034.
The NCP1034 is voltage mode PWM controller for a high voltage
synchronous buck. The controller drives two external N-MOSFETs
with programmable frequency up to 500 kHz for wide applications
range. The IC is able to be synchronized by external signal or is able to
synchronize other ICs that simplify design of system level filter.
The output voltage can be set as low as 1.25 V. Besides system and
drivers UVLO there is an external UVLO that can be set to user value.
Over current protection uses low side MOSFET R
DSON
as sensing
resistor, which has no impact on efficiency. Current limit protection
uses a hiccup mode. These protections provide application additional
security level.
Connection Diagram
•
•
•
•
•
•
•
•
•
High Input Voltage
High Operation Frequency
High Efficiency
Low Output Voltage Ripple
Ceramic Capacitors Only
Over-current Protection
Under-voltage Protection
Start to Pre-biased Output
Small Size
−
+
Power
Supply: 48 V
±20%
Shut
Down
+
+
Load: 5 V
<5A
−
−
−
Ext.
Sync
Signal
+
Figure 1. Connection Diagram
©
Semiconductor Components Industries, LLC, 2016
1
January, 2016 − Rev. 2
Publication Order Number:
EVBUM2356/D
EVBUM2356/D
The demo board was designed as board with many
options. There is linear regulator for powering the IC only
with Zener diode or with high voltage transistor (R12A and
R12B selected one of these regulators), compensation
circuit of second or third type (R14A and R14B), ceramic or
electrolytic output capacitors (C9A–C9E) and various input
capacity (C1A–C1F). For additional filtering there are R13
and C11 which is not currently used. There are two headers
pins for easy connection to external synchronization pulse
source or to direct connection to the other NCP1034 demo
board and the SS/SD pin that can be used to shut down the
controller by connecting it to the ground.
Circuit Layout
Circuit is designed on two layer FR4 board with 72
mm
copper cladding. Except connectors all components are
surface mounted types and almost all of them are on the top
layer. On the bottom side there are power MOSFETs
because it can be easy put on cooler (if demo board is used
on prescribed operations conditions and at room
temperature it is not needed).
Some components must be placed very carefully.
Blocking capacitors C2, C3 and bootstrap capacitor C4 have
to be placed close to the IC. Low side MOSFET’s source
have to be connected to the IC’s power ground with
minimum resistance and inductance of connection so two
layers connection between them is needed. Feedback and
compensation network should be near the IC to minimize
noise on them. Using signal and power ground connected in
one point near the output connector improves load
regulation. Inductor and output capacitors are placed close
to the MOSFETs and output connector.
Figure 3. Top Layer
Figure 4. Bottom Layer
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