NQB-420DWA-AN Datasheet, PDF (25/36 Pages) CUI INC – FULLY REGULATED ADVANCED BUS CONVERTERS

CUI Inc │ SERIES: NQB-D │ DESCRIPTION: FULLY REGULATED ADVANCED BUS CONVERTERS
date 02/20/2013 │ page 25 of 36
Connections (Top view)
Top view
Pin
1
2
3
4
5
6
7
Bottom view
8
(Best air flow direction is from positive to negative pins.)
9
10
Ambient Temperature Calculation
11
For products with base plate the maximum allowed
ambient temperature can be calculated by using the
12
thermal resistance.
13
14
1. The power loss is calculated by using the formula
15
((1/η) - 1) × output power = power losses (P_d).
η = efficiency of product. E.g. 95 % = 0.95
16
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
significantly 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 airflow.
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Designation
+In
RC
Case
-In
-Out
S+
S-
SA0
SA1
SCL
SDA
PG
DGND
SALERT
CTRL
+Out
Function
Positive Input
Remote Control
Case to GND (optional)
Negative Input
Negative Output
Positive Remote Sense
Negative Remote Sense
Address pin 0
Address pin 1
PMBus Clock
PMBus Data
Power Good output
PMBus ground
PMBus alert signal
PMBus remote control
Positive Output