rev.

page

date

DESCRIPTION: point of load converter

6of 11

09/2010

20050

phone 503.612.2300

www.cui.com

fax 503.612.2383

PART NUMBER: VPOL5A-5-SMT

Figure 3. Positive Remote On/Off Input Drive Circuit

Q1

ON/OFF

Control

+Vin

Remote ON/OFF

Common

Common

+Vo

VPOL5A-5-SMT

Figure 4. Negative Remote On/Off Input Drive Circuit

5.7 UVLO (Under-Voltage Lockout)

The voltage on the Vcc pin determines the start of the operation of the

Converter. When the input Vcc rises and exceeds about 2.0V the

converter initiates a soft start. The UVLO function in the converter has a

hysteresis (about 100mV) built in to provide noise immunity at start-up.

6. Safety

6.1 Input Fusing and Safety Considerations.

Agency Approvals: The power Supply shall be submitted to and receive

formal approval from the following test agencies.

1.The power supply shall be approved by a nationally recognized testing

laboratory to UL/CSA 60950 3

(International)

2. CB Certificate from an internationally recognized test house in

accordance with EN 60950.

The VPOL5A-5-SMT series converters do not have an internal fuse.

However, to achieve maximum safety and system protection, always

use an input line fuse. The safety agencies require a time-delay fuse

with a maximum rating of 10A.

7. Applications

7.1 Layout Design Challenges.

In optimizing thermal design the PCB is utilized as a heat sink. Also

some heat is transferred from the SMT module to the main board through

connecting pins. The system designer or the end user must ensure that

other components and metal in the vicinity of the

VPOL5A-5-SMT series meet the spacing requirements to which the

system is approved.

Low resistance and low inductance PCB layout traces are the norm and

should be used where possible. Due consideration must also be given to

proper low impedance tracks between power module, input and output

grounds. The recommended SMT footprint as shown as figure 5.

PAD SIZE

MIN : 0.120" x 0.095 "

MAX : 0.135" x 0.110 "

Dimensions are in Inches ( millimetes )

Recommended Pad Layout

0.340

0.180

0.160

0.160

0.190

0.350

0.690

0.05

VOUT

TRIM

GND

VIN

ON/OFF

(4.57)

(4.06)

(4.06)

(4.83)

0.06

(1.5)

(1.3)

(17.53)

(8.89)

0.010

(0.25)

(8.64)

Figure 5. Recommended SMT Footprint (Top View)

Q1

VPOL5A-5-SMT

ON/OFF

Control

+Vin

+Vo

Remote ON/OFF

Common

Common