LMZM23600

8.4 Device Functional Modes

8.4.1 Shutdown

The LMZM23600 device shuts down most internal circuitry and high-side and low-side power MOSFETs under any of the following conditions:

1.EN is low

2.VIN is below the falling UVLO threshold

3.Junction temperature exceeds TSD threshold

The PGOOD flag remains operational with input voltage as low as 1.5 V.

8.4.2 FPWM Operation

If MODE/SYNC is above the VMODE/SYNC high threshold or a valid synchronizing is applied to MODE/SYNC, constant frequency operation is maintained across load. The ADJ option of the device folds back the frequency

when VIN exceeds 28 V typical so that the output voltage can be properly regulated. See Table 2 for all use cases and options. FPWM mode requires negative current be allowed in the inductor if the load is light. If a large negative load is present, operation is halted by a reverse current limit, IL-NEG.

8.4.3 Auto PFM Mode Operation

If MODE/SYNC is below the VMODE/SYNC low threshold, reverse current in the inductor is not allowed. This feature is called diode emulation. While the load is heavy, the regulator uses PWM mode to control the output. If the load

is light, the control logic transitions to PFM mode. The switching frequency is reduced, resulting in excellent energy savings while regulation is maintained. Because the frequency is reduced and switching pulses can come in groups, the output voltage ripple can increase slightly. Under this condition, the output ripple can be reduced by increasing the output capacitance.

Product Folder Links: LMZM23600