NCP1397A データシートの表示（PDF） - ON Semiconductor

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NCP1397A

High Performance Resonant Mode Controller with Integrated High-Voltage Drivers

ON Semiconductor 

NCP1397A, NCP1397B

R18

Figure 1. Typical Application Example

PIN FUNCTION DESCRIPTION

Pin # Pin Name

Function

1

CSS(dis)

Soft−Start Discharge

2

Fmax

Maximum frequency clamp

3

Ctimer

Timer duration

4

Rt

Minimum frequency clamp

5

BO

Brown−Out

6

FB

7

DT

8 Skip/Disable

Feedback

Deadtime

Skip or Disable input

9

Fault

Fault detection input

10

GND

11

Mlower

12

VCC

13

NC

14

HB

15

Mupper

16

Vboot

Analog ground

Low side output

Supplies the controller

Not connected

Half−bridge connection

High side output

Bootstrap pin

Pin Description

Soft−start capacitor discharge pin. Connect to the soft−start capacitor to reset it

before startup or during overload conditions.

A resistor sets the maximum frequency excursion

Sets the timer duration in presence of a fault

Connecting a resistor to this pin, sets the minimum oscillator frequency reached

for VFB = 1 V.

Detects low input voltage conditions. When brought above Vlatch (4 V typically), it

fully latches off the controller.

Injecting current into this pin increases the oscillation frequency up to Fmax.

A simple resistor adjusts the dead−time width

Upon release, a clean startup sequence occurs if VFB < 0.3 V. During the skip

mode, when FB doesn’t drop below 0.3 V, the IC restarts without soft−start

sequence.

When asserted, the external timer starts to countdown and shuts down the

controller at the end of its time duration. Simultaneously the Soft−Start discharge

switch is activated so the converter operating frequency goes up to protect

application power stage. This input features also second fault comparator with

higher threshold (1.5 V typically) that:

A) Speeds up the timer capacitor charging current 8 times – NCP1397A

B) latches off the IC permanently – NCP1397B

In both versions the second fault comparator helps to protect application in case

of short circuit on the output or transformer secondary winding.

−

Drives the lower side MOSFET

The controller accepts up to 20 V

Increases the creepage distance

Connects to the half−bridge output

Drives the higher side MOSFET

The floating VCC supply for the upper stage

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