
KA3504
4
Pin Definitions
Pin No.
Name
Pin Function Description
1
VS33
Over Voltage Protection Input for the 3.3V. It Directly Senses the 3.3V Rail
Without any External Divider.
2
VS5
Over Voltage Protection Input for the 5V. It Directly Senses the 5V Rail Without
any External Divider.
3
VS12
Over Voltage Protection Input for the 12V. It Directly Senses the 12V Rail
Without any External Divider.
4
PGI
Power Good Signal Generator Input. It Should be Supplied From a Bulk
Dependent Voltage in Order to Detect Power on and off State.
5
V
CC
Supply Voltage. Its Recommended Operating Voltage is Ranged from 15V to
30V.
6
FPO
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".
7
PSON
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.
8
T
PSON
Timing pin for PSON Delay. Ton/Toff=8ms/24ms (Typ.) with Cpson=0.1
μ
F
Externally. PSON On Delay Time (Ton) is Measured as PSON Input Goes Low to
High. PSON Off Delay Time (Toff) can be Measured Reversely.
9
PGO
Power Good Output Signal (Open Collector).
PGO = "High" means "Power Good" for Operation and PGO = "Low" Means
"Power Fail".
10
T
PG
Timing pin for PGO delay. TPG = 270ms (Typ.) with CPG = 2.2
μ
F 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
T
PROT
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
μ
F).
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
at Pin11 to Ground,
the Reference Current(Iref) Should be 20
μ
A. After that, you can Make a
Constant OCP Offset Voltage (V
OFFSET
= R
O
×
5
×
Iref).
In Case the Voltage Drop (=I
O
.
12
×
R
S
) of the Sense Resistor or Inductor is
Larger 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
Equation. (I
O.12
= V
OFFSET
/ R
S
)
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).