BD9775FV-E2 Rohm Semiconductor, BD9775FV-E2 Datasheet - Page 6

• Manufacturer Part Number: BD9775FV-E2
• Description: IC REG SW STEP DOWN HE 28-SSOP
• Manufacturer: Rohm Semiconductor
• Type: Step-Down (Buck)r

Specifications of BD9775FV-E2

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 2
• Current - Output: 400mA
• Frequency - Switching: 100kHz
• Voltage - Input: 6 ~ 30 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-SSOP
• Power - Output: 640mW
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: BD9775FV-E2TR

●Setting Up Information
© 2011 ROHM Co., Ltd. All rights reserved.
BD9775FV
www.rohm.com
1) Simultaneously OFF Duty of MOSFETs for Synchronous Rectification
The simultaneously OFF duty of both main MOSFET switch and synchronous rectification MOSFET is determined by
resistance (Rsync) between SYNC and GND. See Fig.3. In Synchronous Rectification, insert RFB2-GND (RFB2-GND≒3
×Rsync) between FB2 and GND, because it is possible to reduce overshoot(see Fig.3). RFB2-GND decides following
formula.
・Resistance at FB2-GND setup condition
Short SYNC to VREF if the synchronous rectification function is not needed.
Without Synchronous Rectification(Don’t insert R
※Rsync(MAX)…MAX dispersion range at Rsync
40
35
30
25
20
15
10
5
0
0
3×Rsync(MAX)
Vsync
Threshold Voltage at100%
20
SYNC
Rsync(MAX)
-Output Source Current at FB2
0.4908
2.08
40
Rsync
Rsync (kΩ)
+80.7x10
Fig.3
SYNC
VREF
Rsync(MIN)…MIN dispersion range at Rsync
60
-6
FB2-GND
FB2
<
6/14
)
R
FB2-GND
< R
80
FB2-GND
T=-40℃
T= 25℃
T=105℃
< 3xRsync(MIN)
R
FB2-GND
< 3xRsync(MIN)
100
OUT2H
OUT2L
t1
t
Technical Note
2011.05 - Rev.A
t2