M62222L Просмотр технического описания (PDF) - Renesas Electronics
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M62222L Datasheet PDF : 6 Pages
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M62222L/FP
Application Circuit (2.7 V Output DC/DC Converter)
VIN (5 V)
+
100 µF
VOUT (2.7 V, 1 A)
+
100 µF
5 IN
RCLM
0.1 Ω
4
VCC
M62222
3
CLM
1 kΩ
Collector 1
1 kΩ
GND
2
68 µH
Figure 1 Example of the M62222L/FP Application Circuit
• Current limit detection:
When the voltage drop between pin 3 and pin 4 becomes more than 150 mV, the current limit detection circuit
begins operating. The peak switch current "Ipk" is limited to 150 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: 110 kHz (VCC = 5 V)
(TON + TOFF) / ( 1 +
TON )
TOFF
1
fOSC
− TOFF
(VIN − VCE (sat) − VO) × TON (MAX)
∆lO
lO +
1
2
∆lO
0.15
Ipk
∆VCLM: 150 mV (VCC = 5 V)
Note:
VF: Forward voltage drop of an external diode.
Vsat: Output saturation voltage of an external switching transistor.
∆IO: It should be set between 1/3 and 1/5 of maximum output current.
An external transistor, diode and inductor should have a peak current capability of greater than “Ipk”.
Rev.2.00 Jun 14, 2006 page 4 of 5
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