JAJSBZ4B June 2014 – January 2018 LM46001
The LM46001 only requires a few external components to convert from a wide range of supply voltage to output voltage. Figure 44 shows a basic schematic when BIAS is connected to VOUT . This is recommended for VOUT ≥ 3.3 V. For VOUT< 3.3 V, connect BIAS to ground, as shown in Figure 45.
The LM46001 also integrates a full list of optional features to aid system design requirements, such as precision enable, VCC UVLO, programmable soft-start, output voltage tracking, programmable switching frequency, clock synchronization and power-good indication. Each application can select the features for a more comprehensive design. A schematic with all features utilized is shown in Figure 46.
The external components have to fulfill the needs of the application, but also the stability criteria of the device control loop. The LM46001 is optimized to work within a range of external components. The LC-output-filter inductance and capacitance must be considered in conjunction, creating a double pole, responsible for the corner frequency of the converter. Table 2 can be used to simplify the output filter component selection.
|FS (kHz)||L (µH)(1)||COUT (µF) (2)||CFF (pF) (3)(4)||RT (kΩ)||RFBB (kΩ) (3)(4)|
|VOUT = 1 V|
|500||6.8||330||none||80.6 or open||100|
|VOUT = 3.3 V|
|500||18||100||33||80.6 or open||442|
|VOUT = 5 V|
|500||27||66||33||80.6 or open||249|
|VOUT = 12 V|
|200||100||33||see note (5)||200||93.1|
|500||47||22||47||80.6 or open||93.1|
|VOUT = 24 V|
|200||180||22||see note (5)||200||44.2|
|500||82||15||see note (5)||80.6 or open||44.2|
|1000||47||10||see note (5)||39.2||44.2|