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ZHCSCW5B August 2014 – September 2017 LM43600

PRODUCTION DATA.

9.2 Typical Applications

The LM43600 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 V_OUT. This is recommended for V_OUT ≥ 3.3 V. For V_OUT< 3.3 V, connect the BIAS pin to ground, as shown in Figure 45.

Figure 44. LM43600 Basic Schematic for
V_OUT ≥ 3.3 V, Tie BIAS to V_OUT

Figure 45. LM43600 Basic Schematic for
V_OUT< 3.3 V, Tie BIAS to Ground

The LM43600 also integrates a full list of optional features to aid system design requirements, such as precision enable, V_CC 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.

Figure 46. LM43600 Schematic with All Features

The external components have to fulfill the needs of the application, but also the stability criteria of the device's control loop. The LM43600 is optimized to work within a range of external components. The LC output filter's inductance and capacitance have to 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.

Table 2. L, C_OUT and C_FF Typical Values

F_S (kHz)	L (µH)⁽¹⁾	C_OUT (µF) ⁽²⁾	C_FF (pF) ⁽³⁾⁽⁴⁾	R_T (kΩ)	R_FBB (kΩ) ⁽³⁾⁽⁴⁾
V_OUT = 1 V
200	22	500	none	200	100
500	10	330	none	80.6 or open	100
1000	4.8	180	none	39.2	100
2200	2.2	100	none	17.8	100
V_OUT = 3.3 V
200	68	220	44	200	442
500	22	100	33	80.6 or open	442
1000	15	47	18	39.2	442
2200	6.8	27	12	17.8	442
V_OUT = 5 V
200	82	150	68	200	255
500	33	66	33	80.6 or open	255
1000	18	33	22	39.2	255
2200	6.8	22	18	17.8	255
V_OUT = 12 V
200	150	33	see note ⁽⁵⁾	200	90.9
500	56	22	47	80.6 or open	90.9
1000	27	15	33	39.2	90.9

(1) Inductor values are calculated based on typical V_IN = 12 V. For V_OUT = 12 V, typical V_IN = 24 V.

(2) All the C_OUT values are after derating. Add more when using ceramics

(3) R_FBT = 0 Ω for V_OUT = 1 V. R_FBT = 1 MΩ for all other V_OUT settings.

(4) For designs with R_FBT other than 1 MΩ, adjust C_FF such that (C_FF × R_FBT) is unchanged and adjust R_FBB such that (R_FBT / R_FBB) is unchanged.

(5) High ESR C_OUT gives enough phase boost, and C_FF not needed.

9.2 Typical Applications

Table 2. L, COUT and CFF Typical Values

Table 2. L, C_OUT and C_FF Typical Values