AMG-XB404 Datasheet, PDF (35/73 Pages) alpha microelectronics gmbh – Fully Integrated Single Motor Controller for Electrical Motors

AMG-XB404
Fully Integrated Single Motor Controller for Electrical Motors
5.6. Switch Mode Power Supply (SMPS)
The AMG-XB404 SMPS's features:
 Constant frequency, discontinuous conduction mode (DCM)
 Primary coil current control input
 One directly regulated output voltage
 Other output voltages (depending on the transformer) indirectly regulated
 Independent low frequency start-up clock source
 Automatic clock selector to enable system clock after start-up
 Clock-scaling for higher PWM-Frequencies (10kHz ~ 150kHz)
 Energy saving cycle-skipping mode for low levels of output power
 On-chip over-current protection with disable function
HV
R1
R3
D1
C1
D2 C2 C6
SWVDD
SWVREF
SMPS ^R9
SWDRV
T3
SWI
C5
SWVFB
SWV
R8
DGND
VREF
R2
C3
D3
D4
T2
R7
T1
T4
R4
D5
R5
C4
R6
V (15V)
Aux
D6
5V
Reg
D5V
C7
Figure 19: Example Switch Mode Power Supply application schematic (simplified)
The AMG-XB404's Switch Mode Power Supply operates in constant frequency, discontinuous
conduction mode (DCM). Depending on the external circuitry it is capable of generating at least
one variable output voltage. One of these voltages is directly controlled, the others indirectly. As an
example in figure 19 an adjustable output voltage VAUX of 15V is generated and controlled by using
an external voltage divider (see R5 and R6 in figure 19). The output voltage VAUX of the switching
supply is regulated in such a way that the reference voltage level at the SWVI pin is equal to an
internal reference. The SWVFB pin is used for the compensation of the sense amplifier. The
primary coil's current control loop is closed by means of the SWI input pin.
The logic level signal SWDRV drives a simple external level shifting circuit consisting of T2 through
T4, and R9 which in turn drives the power transistor T1 attached to the primary winding of the
switching supply's transformer. The level shifter supply of nominally 15V is fed by the same
AMG-XB404
Revision: A
2. Nov. 2012 © All rights reserved
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