M51995AP/AFP

REJ03D0835-0201 Rev.2.01 Nov 14, 2007

Page 22 of 40

+

M51995A

VOUT

CLM+

GND

CNF

RNF

RCLM

+

M51995A

VOUT

CLM

−

GND

CNF

RNF

RCLM

(a) In case of CLM+

(b) In case of CLM

−

Figure 10 How to Connect Current Limit Circuit

Intermittent Action and Oscillation Control Section

When the internal current limiting circuit states to operate and also the VF level decreases to lower than the certain level

of some 3 V, the dead-time spreads and intermittent action and OSC control circuit (which is one of the timer-type-

protection circuit) starts to operate.

The intermittent action and OSC control circuit is the one to generate the control signal for oscillator and intermittent

action circuit.

Figure 11 shows the timing-chart of this circuit. When the output of intermittent action and oscillation control is at

“high” level, the waveform of oscillator depends on the VF terminal voltage and the intermittent action circuit begins to

operate.

OSC waveform

of CF terminal

Current limit

signal

Output of current

limit latch

Output of

intermittent action and

OSC control circuit

(a) With current limit signal

(b) Without current limit signal

OSC waveform

of CF terminal

Current limit

signal

Output of current

limit latch

Output of

intermittent action and

OSC control circuit

GND

GND

GND

Figure 11 Timing Chart of Intermittent and OSC Control Circuit