M62290FP Просмотр технического описания (PDF) - Renesas Electronics

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M62290FP

5.0 V Fixed Output Voltage DC/DC Converter

Renesas Electronics 

M62290L/FP

Application Circuit (5 V Output DC/DC Converter)

VIN (12 V)

RCLM

0.09 Ω

+

100 µF

VOUT (5.0 V, 1 A)

+

100 µF

5 IN

4

VCC

M62290

3

CLM

Collector 1

1 kΩ

1 kΩ

GND

2

150 µH

Figure 1 Example of Application Circuit of the M62290L/FP

• Current limit detection:

When the voltage drop between pin 3 and pin 4 becomes more than 140 mV, the current limit detection circuit

begins operating. The peak switch current "Ipk" is limited to 140 mV/RCLM. In the example of application

(Figure 1), the current is limited to 1.5 A.

The Expression of Circuit Constants

Constants

TON

TOFF

(TON + TOFF) MAX

TOFF (MIN)

TON (MAX)

L (MIN)

lpk

RCLM

Expressions

VO + VF

VIN − VCE (sat) − VO

1

fOSC

fOSC: 120 kHz (VCC = 12 V)

(TON + TOFF) / ( 1 +

TON )

TOFF

1

fOSC

− TOFF

(VIN − VCE (sat) − VO) × TON (MAX)

∆lO

1

lO + 2 ∆lO

0.14

Ipk

∆VCLM: 140 mV (VCC = 12 V)

Note:

VF: Forward voltage drop of an external diode.

Vsat: Output saturation voltage of an external switching transistor.

∆IO: Set between 1/3 and 1/5 of the maximum output current.

An external transistor, diode and inductor must be have a peak current capability of approximately greater than

"Ipk".

REJ03D0850-0300 Rev.3.00 Jun 15, 2007

Page 7 of 10

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