Datasheet

cui.com
date 11/07/2014 │ page 25 of 36CUI Inc │ SERIES: NQB-D │ DESCRIPTION: FULLY REGULATED ADVANCED BUS CONVERTERS
Top view
Bottom view
For products with base plate the maximum allowed
ambient temperature can be calculated by using the
thermal resistance.
1. The power loss is calculated by using the formula
((1/η) - 1) × output power = power losses (P
d
).
η = efciency of product. E.g. 95 % = 0.95
2. Find the thermal resistance (R
th
) in the Thermal
Resistance graph found in the Output section for
each model. Note that the thermal resistance can be
signicantly reduced if a heat sink is mounted on the top
of the base plate.
Calculate the temperature increase (ΔT).
ΔT = R
th
x P
d
3. Max allowed ambient temperature is:
Max T
P1
- ΔT.
E.g. NQB-468 at 2m/s:
1. ((1/0.95) - 1) × 468 W = 24.6 W
2. 19.5 W × 2.8°C/W = 69.0°C}
3. 125 °C - 69.0°C = max ambient temperature is 56°C
The actual temperature will be dependent on several
factors such as the PWB size, number of layers and
direction of airow.
Ambient Temperature Calculation
(Best air ow direction is from positive to negative pins.)
Connections (Top view)
Pin Designation Function
1 +In Positive Input
2 RC Remote Control
3 Case Case to GND (optional)
4 -In Negative Input
5 -Out Negative Output
6 S+ Positive Remote Sense
7 S- Negative Remote Sense
8 SA0 Address pin 0
9 SA1 Address pin 1
10 SCL PMBus Clock
11 SDA PMBus Data
12 PG Power Good output
13 DGND PMBus ground
14 SALERT PMBus alert signal
15 CTRL PMBus remote control
16 +Out Positive Output
For more information, please visit the product page.