BD8622EFV [ROHM]
Built-in 1ch FET Light Load Type DC/DC converters; 内置1通道FET轻载型DC / DC转换器
| 型号： | BD8622EFV |
| 厂家： | 
ROHM |
| 描述： | Built-in 1ch FET Light Load Type DC/DC converters |
| 文件： | 总16页 (文件大小：770K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
TECHNICAL NOTE
System Power Supply for TV Series
Built-in 1ch FET
Light Load Type
DC/DC converters
BD8622EFV
●Description
BD8622EFV has realized the high performance and reliability required as a power supply for thin-screen TV.
Due to the high-speed load response, it is most suitable for TV-purpose processors with increasingly high performance, and due to the
wide phase margin it leaves a good margin for board pattern & constant setting and so facilitates its application design.
As a high-reliability design, it has various built-in protection circuits (overcurrent protection, output voltage abnormal protection, thermal
protection, and off-latch function at the time of abnormality etc.), therefore as an advantage it does not easily damage in every possible
abnormal condition such as all-pin short circuit test etc. and hence most suitable for thin-screen TV which requires the high reliability.
●Features
1) High efficiency in all load area
2) 3.0A output current
3) PWM mode/PFM mode switch(automatic operation)
4) Low current mode/Rorripplmord switch with terminal MODE
5) Low RDS(ON) internal switches：75mΩ(typ.)
6) ±1% reference voltage accuracy
7) Programmable frequency : 250kHz-1MHz
（Can the adjustment by an external synchronization and the terminal RT resistance.）
8) Terminal RT OPEN/SHORT detecting function
9) Over current protection function
10) Output over voltage/low voltage protection function (over : FB > VREF +60mV , low : FB < VREF -60mV)
11) Timer off latch function in abnormal circumstances
12) Thermal shutdown function
13) Under voltage protection
14) Soft start/start delay circuit
15) Soft start time out function
16) Protecting BUS function with terminal PDET
17) HTSSOP-B20 package
Jul. 2008
● Electrical characteristic
(Unless otherwise noted Ta=25℃, VIN=3.3V, GND=0V)
Specification value
TYP
Parameter
Symbol
UNIT
Condition
MIN
MAX
VIN supply current (operating)
VIN supply current (standby)
Reference voltage (VREF)
Output rise detection voltage
Output decrease detection voltage
Terminal PDET output current
Oscillation frequency
Pch FET ON resistance
UVLO voltage
SW leak current
EN terminal H threshold voltage
EN terminal L threshold voltage
FC sink current
FC source current
SS/DELAY terminal source current
Terminal PDET pull-up resistor
IQ_active
IQ_stby
VREF
VOVP
VLVP
IPDET
fOSC
RPFET
VUVLO
ILSW
VENH
VENL
IFCSI
IFCSO
ISSSO
RPDET
-
-
210
0
0.8
60
-60
-
550
75
2.50
0
350
1
0.808
90
-30
-
600
110
2.65
1
-
0.4
-
-10
6
250
μA
μA
V
mV
mV
mA
kHz
mΩ
V
μA
V
V
μA
μA
μA
kΩ
VFB = 0.83V, VFC = 1V
VEN = 0V
0.792
30
-90
0.4
500
-
2.35
-
1.1
-
Monitoring FB terminal
Monitoring FB terminal
VPDET< 0.3V
RRT= 220kΩ
ISW = 1A
VEN= 0V, VIN = 5.5V
-
-
10
-
2
20
-20
4
100
170
VFB :FB terminal voltage, VEN :EN terminal voltage, VFC :FC terminal voltage, VPDET: PDET terminal voltage
Current capability should not exceed Pd.
2 / 15
● Block Diagram
OSC
Err AMP
Detect Abnormal
Voltage
and Start error
Shut
Down
en
enable
PWM/PFM
CONTROL
SVIN
Predrive
10
VIN
Fig1 Block diagram
● Pin Description
Description
Explanation
No.
1
Symbol
Small signal system GND
Output voltage detection
Signal GND terminal
Feed back terminal
SGND
2
FB
3
PDET
Abnormal state notification and external IC
abnormality detection terminal
Protecting BUS communication terminal
4
5
NC
SW
SW
SW
SW
NC
6
Switching output terminal
7
8
9
10
11
12
13
14
15
16
17
GND for power MOSFET
Power GND terminal
PGND
VIN
VIN
VIN
VIN
NC
Power supply input. The decoupling is done to PGND
Power supply input terminal
ON/OFF control for device operation
Enable input
EN
MODE
The operation mode is switched according to the input voltage
at a light load.
MODE selection terminal
18
19
20
The soft start time is adjusted with the connected capacitor
Error amplifier phase compensation point
The switching frequency is set by the connected resistance
Soft start adjustment capacity connection terminal
Error amplifier output
SS/DELAY
FC
Frequency adjustment resistance connection terminal
RT
3 / 15
● Pin equivalence circuit diagram
No.
Symbol
Explanation
Terminal equivalent circuit diagram
1
SGND
GND (connected 0V)
2
FB
Output voltage detection terminal
3
PDET
Protecting BUS I/O terminal
5,6,7,8
SW
Output terminal
Power GND
(Same voltage as SGND)
10
11,12,13
14
PGND
PVIN
SVIN
Power supply input terminal
Power supply input terminal
4 / 15
No.
Symbol
Explanation
Terminal equivalent circuit diagram
16
EN
Enable terminal
Operation mode switch terminal
at light load
17
MODE
5 / 15
No.
Symbol
Explanation
Terminal equivalent circuit diagram
SS
/DELAY
Soft start time adjustment
terminal
18
Error amplifier compensation
terminal
19
FC
Oscillator frequency adjustment
terminal
20
RT
6 / 15
● Operation description
Enable control
The device can be controlled ON/OFF by EN terminal (16 pin) voltage.
An internal circuit starts when VEN reaches 1.1V.
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.
Fig.2 ON/OFF transition wave form in EN controlling
7 / 15
Soft start time set function
As for BD8622EFV, output can do soft start without overshoot by charging soft start capacity (CSS) connected between
SS and SGND terminal.
Also, soft start time (tss) can be set by setting soft start capacity (CSS) arbitrarily.
OSC oscillation frequency setting function
The output oscillation frequency can be set by connecting resistance between terminal RT (20 pins) and SGND
(range = 250kHz - 1MHz)
The relation between RT terminal resistance and the oscillation frequency follows Fig.4.
1000
10
10
100
1000
10000
RT terminal resistance [kΩ]
Fig.4 RT resistance-oscillation frequency
8 / 15
Light load mode operation
・Low current mode
When the terminal MODE (17 pins) is made "H", low current mode operation becomes effective. The characteristic of the
efficiency valuing is obtained in low current mode operation at a light load.
VOUT
[20mV/DIV]
SW
[2V/DIV]
IL
[200mA/DIV]
Fig.5 Low current mode operation
・Low ripple mode
When the terminal MODE is made "L", the Low ripple mode operation becomes effective. It becomes operation of valuing
a low ripple in the Low ripple mode operation at a light load.
VOUT
[20mV/DIV]
SW
[2V/DIV]
IL
[200mA/DIV]
Fig.6 Low ripplemord operation
100
90
Low current mode
80
70
60
50
40
Low ripple mord
VIN=3.3V
VO=1.8V
30
Io=0～100mA
SW_f=550KHz(R11=220KΩ)
20
10
0
1
10
100
Negative overcurrent[mA]
Fig7 Light load mode efficiency comparison
9 / 15
● Protection function
Protection circuit is effective for destruction prevention due to accident so that avoid using under continuous protection
operation.
Low voltage protection function (LVP)
The voltage of the terminal FB (2 pins) is compared with internal reference voltage VREF.
If FB terminal voltage falls below VLVP(= VREF -60mV) and the state continues for 500us, output changes to low voltage
and the state is fixed. In that case , PDET (3pin) output changes to L.
Table 4-1 output low voltage protection function
EN
terminal
>VENH
Low voltage
protection function
Low voltage
protection operation
SS terminal
FB terminal
＜VLVP
ON
>1.4V(typ)
Effective
＞VLVP
OFF
OFF
OFF
<1.4V(typ)
-
-
-
Invalidity
Invalidity
<VENL
＊ Low voltage protection function is available when SS terminal voltage becomes more than
1.4V (typ) in the transition to ON control (during soft start).
Over voltage protection function(OVP)
The voltage of the terminal FB is compared with internal reference voltage VREF.
If FB terminal voltage is over Vovp (=VREF +60mV) and the state is continues for 500usec, output changes to low voltage
and the state is fixed.
Table 4-2 output overvoltage protection function
EN
terminal
>VENH
Over voltage
protection function
Over voltage
protection operation
SS terminal
FB terminal
＞VOVP
ON
>1.4V(typ)
Effective
＜VOVP
OFF
OFF
OFF
<1.4V(typ)
-
-
-
Invalidity
Invalidity
<VENL
＊ Over voltage protection function is available when SS terminal voltage becomes more than
1.4V (typ) in the transition to ON control (during soft start).
Fig.8 Output voltage error detection range
10 / 15
Under voltage lock out protection (UVLO)
As for BD8622EFV, the power-supply voltage decrease detection protection circuit is built in.
It the input voltage decrease below the UVLO voltage (2.5V typ), the device state changes to the standby mode (Moreover,
to prevent the chattering of the output) hysteresis width of 100mV(typ) has been installed in the UVLO cancel voltage.
RT terminal open/short protection function (RTO/RTS)
RT terminal opening/short protection function prevent the clock from abnormal oscillation.
If RT terminal open/short protection function is detected, output voltage changes to low level and is fixed.
Terminal RT opening/short protection function is available if the state continue for 500usec, abnormal
detection operates when the state continues about 500μsec(typ).
Soft start time-out function
If VSS doesn't exceed VSSTH within 64msec (typ) since a soft start began, BD8622EFV controls an off latch.
Vo is fixed in a low level.
Fig.9 Soft start time-out
Thermal shut down function
Thermal shut down circuit (TSD circuit) is built into BD8622EFV. When the temperature of the chip exceeds Tjmax=175,
the DC/DC converter is fixed in a low voltage.
TSD function is aimed to shut down IC from thermal reckless driving under an abnormal state to exceed Tjmax=175.
It aims at neither protection nor the guarantee of the set. Therefore, please do not use this function to protect the set.
Over current protection function
The over current protection function has been achieved by limiting the current that flows on high side MOSFET.
The current is controlled in every one cycle of the switching frequency. When an abnormal state continues for about
500μsec(typ), the output is fixed in a low level.
11 / 15
Protecting BUS function with terminal PDET
The terminal PDET (3 pins) monitors whether IC is normal or not. When IC becomes abnormal, the PDET output is
reduced at "L" level with the output voltage fixed “L” level at the same time. Moreover, it is possible to make the output fix in
a low level by compulsorily reducing the terminal PDET at "L" level from the outside.
When two or more BD8622EFV is used in the application, this function prevents the IC from destroying, because one IC
error transmits all other ICs by PDET line in the condition that PDET terminals are connected each other.
Fig.6 Protecting BUS communication
※Please give the terminal PDET as OPEN when you do not use protecting BUS function.
Error detection (off latch) release method
BD8622EFV enters the state of an off latch when the protection function operates.
To release the off latch state, EN terminal voltage should be changed to low level once time.
12 / 15
● Each characteristic reference data
Vout : 100mV/div
VIN = 5V
Io = 3A
Vout : 20mV/div
Io = 1A/div
100usec/div
1usec/div
Fig.11 Output load response
Fig.12 Output ripple
VIN = 3.3V
VIN = 2V/div
VOUT = 0.5V/div
SS = 2V/div
VIN = 5.0V
VOUT = 1.8V
fosc = 550kHz
LC mode
10msec/div
Fig.13 Efficiency
Fig.14 Soft start
VIN = 5.0V
VOUT = 1.8V
Fig.15 Regulation
13 / 15
VIN = 3.3V
VIN = 3.3V
Fig.16 Reference voltage - Temperature characteristic
Fig.17 SS Charging current - Temperature characteristic
VIN = 3.3V
Ta = 25℃
Fig.18 Switching frequency-power-supply voltage characteristic
Fig.19 Switching frequency-temperature characteristic
VIN = 3.3V
Ta = 25℃
Fig.20 PMOS on resistance-power-supply voltage
Fig.21 PMOS on resistance-temperature characteristic
VIN = 3.3V
Ta = 25℃
VFB = 0.83V
VFC = 1.0V
SW = H
Fig.22 Terminal EN H voltage-temperature characteristic
Fig.23 Circuit current-power-supply voltage characteristic
14 / 15
HTSSOP-B20
<Dimension>
<Tape and Reel information>
Tape
Embossed carrier tape
6.5 0.1
Quantity
Direction
of feed
2500pcs
20
11
E2
(The direction is the 1pin of product is at the upper left when you hold
reel on the left hand and you pull out the tape on the right hand)
1
10
+0.05
−0.03
0.325
0.17
S
0.08
S
0.65
0.2 −+00..0045
Direction of feed
1pin
Reel
（Unit:mm)
※When you order , please order in times the amount of package quantity.
Catalog No.08T274A '08.7 ROHM ©
Appendix
Notes
No technical content pages of this document may be reproduced in any form or transmitted by any
means without prior permission of ROHM CO.,LTD.
The contents described herein are subject to change without notice. The specifications for the
product described in this document are for reference only. Upon actual use, therefore, please request
that specifications to be separately delivered.
Application circuit diagrams and circuit constants contained herein are shown as examples of standard
use and operation. Please pay careful attention to the peripheral conditions when designing circuits
and deciding upon circuit constants in the set.
Any data, including, but not limited to application circuit diagrams information, described herein
are intended only as illustrations of such devices and not as the specifications for such devices. ROHM
CO.,LTD. disclaims any warranty that any use of such devices shall be free from infringement of any
third party's intellectual property rights or other proprietary rights, and further, assumes no liability of
whatsoever nature in the event of any such infringement, or arising from or connected with or related
to the use of such devices.
Upon the sale of any such devices, other than for buyer's right to use such devices itself, resell or
otherwise dispose of the same, no express or implied right or license to practice or commercially
exploit any intellectual property rights or other proprietary rights owned or controlled by
ROHM CO., LTD. is granted to any such buyer.
Products listed in this document are no antiradiation design.
The products listed in this document are designed to be used with ordinary electronic equipment or devices
(such as audio visual equipment, office-automation equipment, communications devices, electrical
appliances and electronic toys).
Should you intend to use these products with equipment or devices which require an extremely high level
of reliability and the malfunction of which would directly endanger human life (such as medical
instruments, transportation equipment, aerospace machinery, nuclear-reactor controllers, fuel controllers
and other safety devices), please be sure to consult with our sales representative in advance.
It is our top priority to supply products with the utmost quality and reliability. However, there is always a chance
of failure due to unexpected factors. Therefore, please take into account the derating characteristics and allow
for sufficient safety features, such as extra margin, anti-flammability, and fail-safe measures when designing in
order to prevent possible accidents that may result in bodily harm or fire caused by component failure. ROHM
cannot be held responsible for any damages arising from the use of the products under conditions out of the
range of the specifications or due to non-compliance with the NOTES specified in this catalog.
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More detail product informations and catalogs are available, please contact your nearest sales office.
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Appendix1-Rev2.0
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