Single-chip Type with Built-in FET type Switching Regulators
Flexible Step-down
Switching Regulator
with Built-in Power MOSFET
BD8649EFV
No.10027EAT45
●Description
The BD8649EFV is a synchronous step-down switching regulator that integrates 2 low resistances N-channel MOSFETs.
It achieves 3A continuous output current over a wide input supply range.
Current mode operation provides fast transient response and easy phase compensation.
●Feature
1) Synchronous rectification with built-in FET type DC/DC converter
2) 3.0A output current
3) Range of operation power-supply voltage 4.5V½18V
4) Reference voltage FB 0.8V±1%
5) Programmable frequency 100kHz½600kHz
6) Over current protection function
7) Thermal shutdown function
8) Under voltage protection
9) Soft start time out function / Soft start delay circuit
10) Programmable OFFLATCH time
●Applications
FPD,DVD,HDD Recorder,STB,Amusement,Other
●Absolute
maximum rating (Ta=25℃)
Parameter
Input supply voltage
BOOT terminal voltage
EN terminal voltage
Input terminal voltage
SW terminal voltage
Output current
Power dissipation
Operating temperature
Storage temperature
Symbol
V
IN
V
BOOT
V
EN
V
INP
*1
Ratings
20
28
GND-0.3
½
V
IN
+0.3
GND-0.3
½
7
GND-0.3
½
V
IN
+0.3
3.5
*2
3.2
*2
-20
½
85
-55
½
150
Unit
V
V
V
V
V
A
W
℃
℃
V
SW
I
OUT
Pd
Topr
Tstg
*1 V
INP
Application terminal: SS/DELAY, FB, FC, RT, PSET
*2 (70mm×70mm, thickness 1.6mm, and four layer glass epoxy substrates)When mounting substrate and the package
back exposure part are connected with solder
Operating at higher than Ta=25℃, 25.6mW shall be reduced per 1
●Operation
condition
Parameter
Input supply voltage
Output current
*
Symbol
V
IN
I
OUT
Ratings
Min.
4.5
-
Typ.
-
-
Max.
18.0
3.0
Unit
V
A
This product is not designed for protection against radioactive rays.
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© 2010 ROHM Co., Ltd. All rights reserved.
1/13
2010.09 - Rev.A
BD8649EFV
●Electrical
characteristic
(Unless otherwise noted Ta=25℃, V
IN
=12V, V
EN
= 3V)
Parameter
V
IN
supply current (operating)
V
IN
supply current (standby)
Reference voltage (VREF)
Oscillation frequency
High side FET ON resistance
Low side FET ON resistance
UVLO voltage
SW leak current
EN terminal H threshold voltage
EN terminal L threshold voltage
SS/DELAY terminal source current
SS/DELAY – FB Offset voltage
PSET terminal source current
PSET terminal threshold voltage
●
●
Technical Note
Symbol
I
Q_active
I
Q_stby
V
FB
f
OSC
R
HFET
R
LFET
V
UVLO
I
LSW
V
ENH
V
ENL
I
SSSO
V
SSFBOST
I
PSET
V
PSET
Limits
Min.
-
-
0.792
270
-
-
3.8
-
1.6
-
2.8
450
3.0
0.8
Typ.
1.5
0.8
0.800
300
110
110
4.0
0
-
-
4.0
600
5.0
1.0
Max.
2.5
1.2
0.808
330
160
160
4.2
5
-
0.4
5.2
750
7.0
1.2
UNIT
mA
mA
V
kHz
mΩ
mΩ
V
μA
V
V
μA
mV
μA
V
Condition
V
FB
= 0.75V
V
EN
= 0V
FB-FC Short
R
RT
= 56kΩ
I
SW
= -1A
I
SW
= 1A
V
IN
Sweep
V
EN
= 0V
V
SS
= 1V
V
SS
= 1V
V
PSET
= 2V
V
FB
:FB terminal voltage,V
EN
:EN terminal voltage,V
SS
:SS/DELAY terminal voltage, V
PSET
:PSET terminal voltage, R
RT
:RT resistor
Current capability should not exceed Pd.
●Package
outline dimension
Product number
BD8649
1 PIN
Lot No.
HTSSOP-B20 (Unit: mm)
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© 2010 ROHM Co., Ltd. All rights reserved.
2/13
2010.09 - Rev.A
BD8649EFV
●Reference
data
0.820
0.815
0.810
Technical Note
0.810
VIN=12V
0.805
Ta=25℃
VFB and FC [V]
VFBとFC[V]
0.800
0.795
0.790
0.785
0.780
-20
-5
10
25
40
55
70
85
VFB and FC [V]
VFBとFC[V]
0.805
0.800
0.795
0.790
4
6
8
10
12
14
16
18
Ta [℃]
VIN[V]
Fig.1 Reference voltage – temperature
characteristic
340
330
320
Fig.2 Reference voltage – VIN characteristic
340
330
VIN=12V
fsw[kHz]
320
310
300
290
280
270
260
Ta=25℃
fsw[kHz]
310
300
290
280
270
260
-20
-5
10
25
40
55
70
85
4
6
8
10
12
14
16
18
Ta [℃]
Fig.3 Frequency – temperature characteristic
5.0
4.8
4.6
4.4
4.2
4.0
3.8
3.6
3.4
3.2
3.0
2.8
2.6
2.4
2.2
2.0
-20
Fig.4 Frequency – VIN characteristic
5.0
4.5
VIN[V]
VIN=12V
4.0
3.5
Ta=25℃
ISS[μA]
ICC[mA]
-5
10
25
40
55
70
85
3.0
2.5
2.0
1.5
1.0
0.5
0.0
4
6
8
10
12
14
16
18
Ta [℃]
VIN[V]
Fig.5
SS/DELAY
charge current - temperature characteristic
320
280
240
320
280
Fig.6 Circuit Current – VIN characteristic
VIN=12V
SW_PGND[mΩ]
240
200
160
120
80
40
0
VIN=12V
VIN_SW[mΩ]
200
160
120
80
40
0
-20
-5
10
25
40
55
70
85
-20
-5
10
25
40
55
70
85
Ta [℃]
Ta [℃]
Fig.7 Hi side FET ON_R - temperature characteristic
320
280
240
Fig.8 Low side FET ON_R - temperature characteristic
320
280
Ta=25℃
SW_PGND[mΩ]
240
200
160
120
80
40
0
Ta=25℃
VIN_SW[mΩ]
200
160
120
80
40
0
4
6
8
10
12
14
16
18
4
6
8
10
12
14
16
18
VIN[V]
VIN[V]
Fig.9 Hi side FET ON_R - VIN characteristic
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Fig.10 Low side FET ON_R – VIN characteristic
3/13
2010.09 - Rev.A
BD8649EFV
●Block
Diagram
Technical Note
FB
1
FC
2
RT
3
PSET
4
EN
5
NC
6
NC
7
VIN
8
VIN
9
VIN
10
EN
PWM
CONTROL
Protect time
OSC
CURRENT
DET
5V
Softstart/Delay
GND
20
SS/DELAY
19
NC
18
BOOT
17
SW
16
SW
15
SW
14
PGND
13
PGND
12
PGND
11
VOUT
Fig.11 Block diagram
●Pin
Assignment
No.
1
2
3
4
5
6
7
8
9
10
Symbol
FB
FC
RT
PSET
EN
NC
NC
VIN
VIN
VIN
Description
Feedback terminal
Phase amends terminal
Frequency adjustment resistance
connection terminal
Adjust OFF LATCH time terminal
Enable input
-
-
Power supply input terminal
Power supply input terminal
Power supply input terminal
No.
11
12
13
14
15
16
17
18
19
20
Symbol
PGND
PGND
PGND
SW
SW
SW
BOOT
NC
SS/DELAY
GND
Description
Power GND terminal
Power GND terminal
Power GND terminal
Switching output terminal
Switching output terminal
Switching output terminal
Boot strap terminal
-
Soft start adjustment capacity
connection terminal
Signal GND terminal
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© 2010 ROHM Co., Ltd. All rights reserved.
4/13
2010.09 - Rev.A
BD8649EFV
●Operation
description
Technical Note
1 Enable control
The device can be controlled ON/OFF by EN terminal (5 pin) voltage.
An internal circuit starts when VEN reaches 1.6V.
When standing up of VIN is too steep (1msec or less), a defective start might be caused according to the state of Pascon
between GND substrate pattern and power supply-when the terminal EN is short-circuited to the terminal VIN and it is
used.
V
EN
EN terminal
V
ENH
V
ENL
0
V
SSCLM
SS terminal
V
SSTH
V
SS
0
V
O
Output setting voltage
0
t
SS
Fig.12 ON/OFF transition wave form in EN controlling
2 Soft start time set function
As for BD8649EFV, output can do soft start without overshoot by charging soft start capacity (C
SS
) connected between
SS/DELAY (19 pin) and GND (20 pin) terminal.
Also, soft start time (tss) can be set by setting soft start capacity (C
SS
) arbitrarily.
(Refer to 5-2 soft start time setting method)
3 OSC oscillation frequency setting function
The output oscillation frequency can be set by connecting resistance between terminal RT (3 pin) and GND
(range = 100kHz – 600kHz)
The relation between RT terminal resistance and the oscillation frequency follows Fig.13.
10000
1000
SW[kHz]
100
10
1
10
100
1000
RT[kΩ]
Fig.13 Oscillation frequency setting by RT resistance
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© 2010 ROHM Co., Ltd. All rights reserved.
5/13
2010.09 - Rev.A
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