a5975d STMicroelectronics, a5975d Datasheet - Page 41

• Manufacturer Part Number: a5975d
• Description: Up To 3 A Step-down Switching Regulator For Automotive Applications
• Manufacturer: STMicroelectronics

A5975D
8.10
8.11
The switch peak current must be lower than the minimum current limit of the overcurrent
protection (see
DC current of the device.
As a consequence, the maximum output current is:
Equation 46
where I
Figure 29
driving (350 mA). To implement a boost conversion the LED string must be composed of a
minimum device number having a total voltage drop larger than maximum input voltage.
The input voltage can be either DC or AC thanks to the input bridge rectifier. In the case of a
DC voltage source D1, D2, D3, D4, C1, and C2 can be removed from the circuit and 1
capacitor value can be used for C5.
Synchronization example
See
Figure 30. Synchronization example
Compensation network with MLCC at the output
The A5975D standard compensation network (please refer to
introduces a single zero and a low frequency pole in the system bandwidth, so a high ESR
output capacitor must be selected to compensate the 180-degree phase shift given by the
LC double pole.
The selection of the output capacitor must guarantee that the zero introduced by this
component is inside the designed system bandwidth and close to the frequency of the
double pole introduced by the LC filter. A general rule for the selection of this compound for
the system stability is provided in
Section 5.3
SW MAX
shows a tested circuit to implement a boost current source for high current LED
represents the rated current of the device.
Table 4
for details.
for details) while the average current must be lower than the rated
Doc ID 018760 Rev 1
A5975D
I
Equation
OUT MAX
≅
I
47.
SW MAX
⋅
(
1 D
–
)
Figure 1
Application information
A5975D
and
Section
7)
AM09694v1
μ
41/50
F