0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
Power (W)
5.00
5.50
6.00
6.50
7.00
7.50
V
-r
e
c
t
R-Ilim 250
R-Ilim 500
R-Ilim 750
0%
10%
20%
30%
40%
50%
60%
70%
80%
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
Power (W)
E
ff
ic
ie
n
c
y
(%
)
R-Ilim 250
R-Ilim 500
R-Ilim 750
Test Setup
6.8
System Efficiency
The efficiency is measured from input of TX EVM, HPA689 to output of RX EVM, HPA764A with 19-V
input. Due to the communication packet that occurs at an approximate 250-ms rate, averaging of input
current and voltage is required for good accuracy. Note that Dynamic Efficiency Scaling will improve
efficiency at lower loads for lower total output currents. This is demonstrated with the higher value for R I-
lim, resulting in lower total output current. See data sheet for additional information regarding Dynamic
Efficiency Scaling.
Figure 8. bq51013AEVM-765 Efficiency vs Output Power
6.9
Dynamic Rectifier Control / Dynamic Efficiency Scaling
V-rect is the voltage controlled by the global feedback loop, it is LDO input. The Dynamic Rectifier Control
algorithm will adjust this voltage based on output current. The Dynamic Efficiency Scaling will adjust V-
rect based on max output current set by R I-lim. The below graph show effect of both features on V-rect
with three different values of R I-limit.
Figure 9. bq51013AEVM-765 V-rect vs Output Power
11
SLUU911 – June 2012
bq51013AEVM-765 Evaluation Module
Copyright © 2012, Texas Instruments Incorporated