NCP1031 ON, NCP1031 Datasheet - Page 2

• Manufacturer Part Number: NCP1031
• Description: Low Power PWM Controller with On-Chip Power Switch and Startup Circuits for 48V Telecom Systems
• Manufacturer: ON

COMP
FUNCTIONAL PIN DESCRIPTION
Pin
GND
VFB
1
2
3
4
5
6
7
8
C
T
V
COMP
Error Amplifier
Name
GND
V
DRAIN
V
OV
UV
C
CC
Internal Bias
FB
10 V
T
10 V
10 V
+
−
I
2.5 V
Error Amplifier Compensation
2 kW
Line Undervoltage Shutdown
2
Line Overvoltage Shutdown
I
−
+
1
= 3I
Oscillator Frequency
Power Switch and
1
Feedback Input
Startup Circuits
Supply Voltage
PWM Comparator
Function
Selection
C
Ground
+
−
3.0 V/3.5 V
T
I
One Shot
Ramp
Pulse
+
−
Current Limit
O
Figure 1. NCP1030/31 Functional Block Diagram
Comparator
4.5 V
Ground reference pin for the circuit.
An external capacitor connected to this pin sets the oscillator frequency up to 1 MHz.
The oscillator can be synchronized to a higher frequency by charging or discharging
C
switch is disabled and the frequency is reduced by a factor of 7.
The regulated voltage is scaled down to 2.5 V by means of a resistor divider.
Regulation is achieved by comparing the scaled voltage to an internal 2.5 V reference.
Requires external compensation network between COMP and V
effectively grounded if faults are present.
Line voltage (V
voltage reaches 2.5 V when line voltage reaches its maximum operating voltage.
Line voltage is scaled down using an external resistor divider such that the UV
voltage reaches 2.5 V when line voltage reaches its minimum operating voltage.
This pin is connected to an external capacitor for energy storage. During Turn−On, the
startup circuit sources current to charge the capacitor connected to this pin. When the
supply voltage reaches V
enabled if no faults are present. An external winding is used to supply power after
initial startup to reduce power dissipation. V
This pin directly connects the Power Switch and Startup Circuits to one of the
transformer windings. The internal High Voltage Power Switch Circuit is connected
between this pin and ground. V
−
+
T
R
NCP1030, NCP1031
to trip the internal 3.0 V/3.5 V comparator. If a fault condition exists, the power
SENSE
+
−
http://onsemi.com
50 mV
LEB
S
R
PWM Latch
Dominant
Reset
Latch
in
) is scaled down using an external resistor divider such that the OV
2
Q
CC(on)
, the startup circuit turns OFF and the power switch is
DRAIN
Shutdown
Description
7.5 V/10 V
Thermal
should not exceed 200 V.
CC
Q
Dominant
should not exceed 16 V.
+
−
−
+
−
+
Reset
Latch
S
R
+
−
2.5 V
Disable
10 V
−
+
−
+
FB
+
−
10 V
10 V
pins. This pin is
+
−
6.5 V
I
START
16 V
V
V
OV
UV
CC
DRAIN