PC POWER SUPPLY SUPERVISORS
DESCRIPTION
The UTC S3515 is specially designed for switching power supply
system. It provides over-voltage protection, over-current protection,
under-voltage protection, on/off control and power good signal generating.
OVP/UVP (Over/Under-Voltage Protection) monitors 3.3V, 5V and
double 12V to protect our power supply and PC, FPO goes to high when
one of these supply voltages exceeds their normal operation voltage
range.
OCP (Over Current Protection) monitors IS33, IS5, IS12 input
current. The voltage difference across external current shunt is used for
OCP functions. An external resistor which is connected between the RI
pin and the GND pin can be used to adjust protection threshold. To
achieve better immunity for lighting surge glitch and to prevent
accidental power shut down during dynamic loading condition, the
de-bounce time for UVP/OCP is 73us respectively. The deglitch time for
OVP is 73uS for better noise immunity.
The power supply is turned on after 38mS de-bounce time when
PSON signal is set from high to low. To turn off power supply, PSON
signal is set from low to high and the de-bounce time is 115mS. When
PGI input voltage level is lower than the internal 1.15V reference
voltage, after 73uS de-bounce time, the PGO signal is pulled low.
FEATURES
* Over/Under-Voltage Protection for 3.3V, 5V, and Two 12V
* Over-Current Protection for 3.3V, 5V, and Two 12V
* PGO and FPO pins with Open Drain Output Stage
* 300mS Power Good Delay from PGI to PGO
* 75mS Delay for 3.3V, 5V and 12V Power Turn on
* 2.8mS Delay for PSON Control to FPO Turn off
* 38mS / 115mS PSON on/off De-Bounce Time
* 73uS width Noise Deglitches
* 73uS De-Bounce Time for UVP and OCP
* Wide Supply Voltage Range |
