KA3505

4

Pin Definitions

Pin No.

Name

Pin Function Description

1V33

Over and Under Voltage Protection Input for the 3.3V. It directly senses the 3.3V

rail without any external divider.

2V5

Over and Under Voltage Protection Input for the 5V. It directly senses the 5V rail

without any external divider.

3V12

Over and Under Voltage Protection Input for the 12V. It directly senses the 12V

rail without any external divider.

4PGI

Power Good Signal Generator Input. It should be supplied from a bulk

dependent voltage in order to detect power on and off state.

Supply voltage. Its recommended operating voltage is ranged from 15V to 30V.

6FPO

Fault Protection Output (Open Collector Output). This pin indicates the fault

condition. When fault state occurs, the PGO signal goes Low.

Normal = ’Low", Fault = "High".

7PSON

Remote on/off input. It does TTL operation and its threshold voltage is 1.4V. In

case of open circuit, the voltage at this pin is High (5.0V). If PSON = "Low", then

FPO = "Low". It means the main SMPS is working. When PSON = "High or

Open", then FPO = "High" and the main SMPS stops to work.

Timing pin for PSON delay. Ton/Toff=8ms/24ms (Typ.) with Cpson=0.1

µF

externally. PSON On Delay Time (Ton) is measured as PSON input goes Low to

High. PSON Off Delay Time (Toff) can be measured reversely.

9PGO

Power Good Output Signal (Open Collector).

PGO = "High" means "Power Good" for operation and PGO = "Low" means

"Power Fail".

10

Timing pin for PGO delay. TPG = 270ms (Typ.) with CPG = 2.2

µF externally. The

high/low threshold voltages are 1.8V/0.6V and the voltage of pin10 would be

charged up to 2.9V for noise margin.

11

RI

OCP current sense setting pin. The reference voltage at this pin is set to 1.25V

internally.You can fix the OCP reference current by using RI resistor.

12

GND

Ground

13

Timing pin for under voltage protection and over current protection blank-out

time. Its threshold voltage is 1.8V and clamped at 2.9V after full charging. Target

of delay time is 38ms and it is realized through external capacitor (C=0.47

µF).

14

IS12

Current sense input for +12V. This pin is connected to the current sensing

resistor or inductor. You can define OCP offset voltage for +12V by using RI

resistor externally. If you connected RI resistor of 62k

Ω at Pin11 to ground, the

reference current(Iref) should be 20

µA. After that, you can make a constant OCP

× 5 × Iref).

than offset voltage, FPO becomes "High" after some delay time and the main

SMPS is turned-off. So the over current level is determined by following

∗ See application note for details.

15

IS5

Current sense input for +5V. You can make the +5V OCP function as previous

method in IS12 (Pin14).

16

IS33

Current sense input for +3.3V. You can also make the +3.3V OCP function as

previous method in IS12 (Pin14).