ha16138 HITACHI, ha16138 Datasheet - Page 10

• Manufacturer Part Number: ha16138
• Description: Ac/dc Switching Converter Controller With High-voltage Power
• Manufacturer: HITACHI

HA16138PS
f-down Comparator
An "energy-saving mode" is provided to hold down power consumption during standby, with the operating
frequency in the unloaded state reduced to 1/4 of its steady operation value.
The f-down comparator detects the COMP pin voltage, and if it falls to 0.85 V or below, switches to
energy-saving mode. As COMP pin voltage detection is performed pulse-by-pulse, a skip mode comes into
effect in the vicinity of the threshold voltage according to the timing.
Over Temperature Protection Circuit
If the power MOS FET junction temperature reaches +150 C, the over temperature protection circuit
operates, shutting down the IC. The over temperature protection circuit is coupled to the OVP latch circuit,
so that the latch is reset if the power supply voltage is driven to 4 V or below while the junction
temperature is lower than the overheating protection start temperature.
10
Figure 6 Energy-Saving Mode Switching Waveform Timing
V
V
V
CT
COMP
DRAIN
Normal
mode
Energy-
saving
mode
Normal
mode
Energy-
saving
mode