TDA8939TH Datasheet, PDF (12/21 Pages) NXP Semiconductors – Zero dead time Class-D 7.5 A power comparator

Philips Semiconductors
TDA8939
Zero dead time Class-D 7.5 A power comparator
13. Output power estimation
The maximum achievable output power is not only determined by the power comparator
characteristics, but by the total system application.
The following application blocks determine the maximum achievable output power:
Power comparator:
• Minimum pulse width
• Series resistances: R_{DS_ON}, bond wires, printed-circuit board tracks, series resistance
of the coil, etc.
System application:
• Power supply voltage
• Load impedance
• Controller characteristics: maximum modulation depth and carrier frequency.
In Figure 6 an estimate is given for the output power in full-bridge application as function
of the (symmetrical) supply voltage for different values of the load-impedance. The
following variables are taken into account:
• Minimum pulse width: 150 ns
• Total series resistance: 0.4 Ω
• Carrier frequency: 384 kHz.
200
P_out
(W)
160
001aaa626
250
P_out
(W)
200
001aaa627
120
(1)
(2)
80
(3)
40
150
(1)
(2)
100
(3)
50
0
10
14
18
22
26
30
V_P (V)
(1) Z_L = 4 Ω.
(2) Z_L = 6 Ω.
(3) Z_L = 8 Ω.
Fig 6. Output power estimation as a function of
(symmetrical) supply voltage for THD = 1 %.
0
10
14
18
22
26
30
V_P (V)
(1) Z_L = 4 Ω.
(2) Z_L = 6 Ω.
(3) Z_L = 8 Ω.
Fig 7. Output power estimation as a function of
(symmetrical) supply voltage for THD = 10 %.
9397 750 13023
Objective data sheet
Rev. 01 — 22 April 2004
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
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