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ISL9120 Datasheet(PDF) 9 Page - Renesas Technology Corp |
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ISL9120 Datasheet(HTML) 9 Page - Renesas Technology Corp |
9 / 13 page ![]() ISL9120 FN8659 Rev.2.00 Page 9 of 13 May 23, 2017 Variable Peak Current Limit Scheme To optimize efficiency across the output current range, the ISL9120 implements a multilevel current limit scheme with 32 levels between 350mA and 2A. The transition from one level to the other is determined by the number of pulses in a PFM burst (pulse count) as shown in Figure 16. At a given peak current limit level, the pulse count increases as the output current increases. When the pulse count reaches the upper threshold at the existing current limit, the current limit will switch to the next higher level. Similarly, if the pulse count reaches the lower threshold at the existing current limit, the device will switch to the next lower level of peak current limit. If the pulse count reaches the upper threshold at the highest current limit, the current limit will not rise any further. Increasing the output current beyond this point may cause the output to lose voltage regulation. FIGURE 15. PFM MODE OPERATION CONCEPT FIGURE 16. PEAK CURRENT LIMIT STEP UP TRANSITION IL VOUT 0 1.015 * VOUT_NOMINAL VOUT_NOMINAL PEAK CURRENT LIMIT IL IOUT 0 IPK_LMT2 IPK_LMT1 INCREASING IOUT tMIN |
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