BD8643FV-E2 Rohm Semiconductor, BD8643FV-E2 Datasheet - Page 9

• Manufacturer Part Number: BD8643FV-E2
• Description: IC SWITCH REG 3A W/FET 20SSOP
• Manufacturer: Rohm Semiconductor
• Series: -r
• Type: Step-Down (Buck), PWM - Current Moder

Specifications of BD8643FV-E2

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 1 V ~ 12.6 V
• Current - Output: 3A
• Frequency - Switching: 100kHz ~ 600kHz
• Voltage - Input: 4.5 V ~ 18 V
• Operating Temperature: -20°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-LSSOP (0.240", 6.10mm Width)
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

BD8643FV
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3 Selection of inductor (L)
Please select the value of the inductor according to the following expressions.
※ Please have and select an enough margin so that the current peak should not exceed the ratings current value of the inductor.
4 Selection of input capacitor (Cin)
Please use a low ESR input capacitor which can be used with high voltage and ripple current to prevent a big transition
voltage.
※ Please put on the input capacitor near side by VIN-PGND.
5 Selection of diode
Please have and set the margin enough to the current rating of the diode for the maximum load current.
Moreover, please similarly have and set the margin enough to a ratings reverse-voltage for the maximum input voltage.
6 OFFLATCH time setting method
If it continues abnormal state, BD8643FV output become low voltage and state is fixed.
In this case, the OFFLATCH time can be set by connecting capacitor between PSET and GND. Please select the value of
OFFLATCH time according to the following expression. Please set OFFLATCH time in 200µsec ～ 5msec.
To release the off latch state, EN or VIN terminal voltage should be changed to low level once time.
T
TM
( ⊿ IL: Output ripple current , f: Switching frequency)
L
=

(V
IN
⊿

I
I
V
PSET
L
OUT

C
V
(5µA typ)
PSET
IN
)


V
f
OUT
[H]
[sec] ・・・ (11)
Fig.19 Phase amends part external circuit chart
FB
9/13
FC
I
L
R1
C1
Fig.18 Current of output ripple
△I
Technical Note
2010.09 - Rev.A
L