ROHM BD8628EFV, BD8624EFV Technical data

TECHNICAL NOTE

System Power Supply for TV Series

Built-in 1ch FET
Synchronous Rectification Type
DC/DC converters

BD8628EFV, BD8624EFV

●Description
BD8628EFV / BD8624EFV have realized the high performance and reliability required as a power supply for thin-screen TV.
With built-in FET 1ch current mode control, the DC/DC Converter series has the advantage of high-speed load response and wide
phase margin.
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) 1ch synchronous rectification step-down system DC/DC converter

2) Soft start, soft off function

3) Built-in low voltage / overvoltage protection function

4) Built-in overcurrent protection function

5) Frequency setting by external resistance is available. (RT terminal)

6) Protection time setting by external resistance is available. (RSET terminal)

7) Built-in RT / RSET terminal open/short protection function

8) Protection control with built-in sequencer

9) Built-in adjustment function time of off latch

10) Built-in error state detection signal output function

11) Built-in tracking function

12) Corresponded to protecting bus

13) Load current Maximum 3A

14) HTSSOP－B24 Package

Aug. 2008

2

F

C

C

R

P

P

t

O

5

_

P

● Electric characteristic

(Ta=25℃, VCC=6.5V, GND=0V,CTL=6.5V unless otherwise specified.)

Parameter Symbol

Circuit current 1
Circuit current 2

I

- 0 10 μA CTL=0V

Q1

I

- 3.4 - mA CTL=VCC

Q

< Error amplifier part >
Standard voltage （VREF） V
Terminal FB Input bias current I
Terminal FC Clamping voltage H
Terminal FC Clamping voltage L
Terminal FC Sink current
Terminal FC Source current I
Open loop gain A

0.792 0.8 0.808 V Terminal FB and FC terminal short

RE

-1 0 1 μA VFB=0.9V

FBB

V

1.8 - - V VFB=0.7V

FCH

V

- - 0.2 V VFB=0.9V

FCL

I

0.5 - - mA VFB=0.9V, V

FCSINK

FCSOURCE

- - -70 μA VFB=0.7V, V

- 100 - dB

VER

<OSC part>

Oscillation frequency F

400 500 600 kHz

OSC

<Soft start >
Charging current ISS -3 -2.5 -2 μA VSS=1.0V
Terminal SS Threshold voltage V
Terminal SS Clamping voltage V
Terminal SS Standby voltage

0.98 1.08 1.18 V V

SSTH

2.2 2.4 - V

SSCLM

V

0.1 0.15 - V V

SSSTB

Terminal SS Discharge resistance RSS 49 70 91 kΩ CTL=0V

Terminal SS Protection circuit start voltage
Terminal SS Protection circuit start voltage
Maximum

hysteresis error

V

SSPON

V

SSPON_HYS

1.0 1.1 1.2 V V

< Low voltage, over voltage detection part＞

Terminal FB Low voltage detection voltage
Terminal FB Overvoltage detection voltage

V

0.51 0.56 0.61 V V

LV

V

0.86 0.96 1.06 V VFB

OV

< Over current detection part＞
Output current limitation threshold I

VCC-0.9 VCC-0.7 VCC-0.5 V VSW

lm

<Power MOS>
Upper side MOS ON resistance R
Lower side MOS ON resistance R

- 110 - mΩ V

ONU

- 110 - mΩ V

NL

<Others＞

Terminal PDET L output voltage
Terminal CTL input voltage H level voltage
Terminal CTL input voltage L level voltage
Terminal CTL input current I

V

- - 0.4 V IOL=100uA

OL

DET

V

2.0 - VCC V CTL terminal

IH_CTL

V

- - 0.5 V CTL terminal

IL_CTL

- 60 90 μA CTL terminal, CTL=VCC

I_CTL

VFB : FB terminal voltage, VFC : FC terminal voltage, VSS : SS terminal voltage, V

Not designed for radiation resistance.

Current capability should not exceed Pd.

specification value

MIN TYP MAX

UNIT Condition

10 100 200 mV V

: MONVCC terminal voltage

MONVCC

When terminal RT 27kΩ is
connected

SS Voltage

SS Voltage

SS Voltage

SS Voltage

FB Voltage

Volt age

Vol tage

BOOT－VSW

=5V

VREG

=0.4V

F

=1.6V

F

(L→H)

(L→H)

=5V

2 / 14

jc

j

T

[

T

x

[

T

T

x

[

T

x

[

T

j

x

[

Permissible loss

This package is a product of which the feature is the high heat radiation, and connect the back to GND
based on recommended land pattern when you mount.

cma

θ

[ ℃ /W]

a

θ

[ ℃/W]

STGmin

]

℃

STGma

℃

]

a min

[℃]

a ma

℃

]

Destruction
temperature

]

℃

ma

Destruction
temperature

]

℃

19.0 31.3 -50.0 150.0 -45.0 85.0 150.0 150.0

Permissible loss ： Pd [W]

ROHM standard substrate specification
Material 4 layer glass epoxy substrate(back copper foil70mm×70mm)
Size 70mm×70mm×1.6mmt(Sarmalbiaing is in the substrate.)

Figure 1 Heat decrease curve

※These values are the actual measurement values, and no guarantee values.

3 / 14

● Block diagram

RSET

PDET

PIO

CTL

VCC

PVCC

PVCC

OSC

OPEN/SHORT

SEQ

Control

RT

Driver

Control

OVP
LVP

RT

OSC

time

PROTECT

BUS

I/F

17

CTL

18 19

OSC

VREF

VREG5

SS

FB

FC

10

GND

９ ８ ７ ５

VREG5

BOOT

SW

６

SW

TEST2

TEST1

N.C.

N.C.

Figure-2 Block diagram・Application diagram

N.C.

４

N.C.

３

PGND

２ １

PGND

● Terminal explanation

No. Symbol Description No. Symbol Description

1 PGND

2 PGND

3 N.C.

4 N.C

5 SW

6 SW

7 BOOT

8 VREG5

9 GND

10 FC

11 F B

12 SS

Soft start adjustment capacity connection terminal

Internal power supply (5.0V) output terminal

Power GND terminal

Power GND terminal

No wire connection.
(Connect to GND. )
No wire connection.
(Connect to GND. )

SW terminal

SW terminal

High side Power MOS gate drive

power source terminal

GND

Phase amends terminal

Feedback terminal

※Please give to VCC+0.3V as an operation condition in all input terminals except the terminal BOOT.

However, please do not exceed the absolute maximum rating as VCC=PVCC.

Table 1 Terminal explanation

13 RT

14 RSET

15

16

ＰＤＥＴ Error state notification terminal

PＩＯ

Frequency adjustment resistance connection terminal

Off latch effective time adjustment resistance terminal

17 CTL

18 VCC

19 PVCC

20 PVCC

21 TEST2

22 TEST1

23 N.C.

24 N.C.

Error state notification

and external IC error detection terminal

Enable input

VCC power supply terminal

Power VCC terminal

Power VCC terminal

Test terminal (Connect to GND. )

Test terminal (Connect to GND. )

No wire connection.

(Connect to GND. )

No wire connection.

(Connect to GND. )

4 / 14

● Terminal equivalent circuit chart

Terminal

No.

1 PGND

2 PGND

5 SW SW terminal

6 SW SW terminal

Terminal

name

Power GND
(The same potential as the GND
terminal)
Power GND
(The same potential as the GND
terminal)

Explanation Terminal equivalent circuit chart

PVCC PVCC

PGND

⑤
⑥

7 BOOT

High side Power MOS gate drive power source
terminal

8 VREG5 Internal power supply (5.0V) output terminal

9 GND GND

VREG5

⑦

PGND

10 FC Phase amends terminal

5 / 14

Terminal

No.

Terminal

name

Explanation Terminal equivalent circuit chart

VCC

VCC

11 FB Voltage detection terminal

12 SS

13 RT

Soft start adjustment capacity connection
terminal

Frequency adjustment resistance connection
terminal

⑪

GND

14 RSET

Off latch effective time adjustment resistance
terminal

15 PDET Error state notification terminal

6 / 14

Terminal

No.

Terminal

name

Explanation Terminal equivalent circuit chart

16 PIO

17 CTL Enable input

21 TEST2 Test terminal (Connect to GND. )

22 TEST1 Test terminal (Connect to GND. )

19 PVCC Power VCC terminal

20 PVCC Power VCC terminal

Error state notification and external IC error
detection terminal

7 / 14

l

● Operation description

ON/OFF control
DC/DC converter ON/OFF function

DC/DC converter controller can be controlled ON/OFF by CTL terminal.
Analog circuit starts operation at ON control (on mode), and goes down to setting output voltage.
Analog circuit should be standby at OFF control (off mode), and output voltage becomes 0V.

Soft start time set function

DC/DC converter can do soft start without overshoot by charging soft start capacity (Css) connected between SS
terminal and GND by charging current at ON control.
The mute of the output is released when it reaches V
operation from the point of V
Also, soft start time (tss) can be set by setting soft start capacity arbitrarily.
Soft start time (tss) should be set at 3msec < tss < 30msec.

※Please note that the overshoot is not caused in the output setting voltage when setting it to tss≦3msec.

Table1 DC/DC converter ON/OFF function

TL terminal voltage

>VIHCTL ON control

<VILCTL

=0.15V (V

SS

=0.3V (typ) in proportion to the voltage of the terminal SS.

SS

FF contro

SSSTB

), and the output voltage does the soft start

V

SS

SSTH



t

C



SS

I

SS

Discharge function

DC/DC converter can do soft off by discharging load discharged to soft start capacity connected between SS terminal
to GND by discharging resistance at OFF control.
Soft off operates in proportion to the voltage of the terminal SS the output voltage from the point of VSS=0.8V (typ).

Figure 2 Wave form at ON/OFF control

8 / 14

0

0

0

0

0

0

OSC oscillation frequency setting function
SW output oscillation frequency of DC/DC converter can be set by installing resistance between RT terminal and GND
externally.

1000

100

10

Switching frequency [KHz]

1

11010

RT terminal resistance[KΩ]

*Reference date

100

Figure 3 Terminal RT resistance-oscillation frequency

Range of terminal RT connection resistance setting
23kΩ≦Rrt≦135kΩ

（100kHz≦fosc≦600kHz）

9 / 14

PROTECT BUS Input/output function
The terminal PIO is PROTECT BUS Input/output terminal. The terminal PIO is Hi-Z when DC/DC usually operates. When the
terminal PIO becomes LOW by connecting PROTECT BUS, DC/DC is turned off. Afterwards, when the terminal PIO becomes
HIGH, it reactivates.
DC/DC is Off latch when DC/DC error detects it and the terminal PDET becomes LOW.

Table2 PIO terminal, PDET terminal output function

DC/DC

Error detection

PIO terminal PDET terminal DC/DC

Undetection Hi-Z Hi-Z ON
Undetection LOW Hi-Z OFF

Detection LOW LOW Off latch

PROTECT BUS Timing chart
If two or more BD8628EFV/BD8633EFV/BD8624FV/BD8630FV is connected in PROTECT BUS, and it uses at the same time,
when one IC error detects, all remaining IC becomes PIO = Low at the same time, and the output is turned off.

Protecting BUS part timing chart

PIO

PIO

IC_A

IC_B

IC_A
PDET

IC_A
PIO

IC_B
PIO

IC_B
Vo

IC_A detects error.

OFF LATCH

High

LOW

High

LOW

High

LOW

DC/DC OFF

0V

IC_B
PDET

When two or more BD8628EFV/BD8633EFV/BD8624FV/BD8630FV is used at the same time,
If one IC error detects, all IC becomes DC/DC OFF at the same time.

High

10 / 14

● Protection function

Protection circuit is effective for destruction prevention due to accident so that avoid using by continuous protection
operation.

Low voltage protection function(LVP)
Low voltage protection function detects set output voltage V
compared to internal reference level.

Low voltage protection function operates when FB terminal voltage falls below V
than set time in external resistance.

CTL

terminal

>VIHCTL

SS terminal FB terminal

>1.1V(typ)

<1.0V(typ) - Disable OFF

<VILCTL - - Disable OFF

※Constant voltage protection function is enabled when SS terminal voltage becomes more than 1.1V (typ) in the transition

to ON control (during soft start).

Overvoltage protection function (OVP)
Overvoltage protection function detects set output voltage VO from FB terminal and off-latched DC/DC converter
controller compared to internal reference level.

Overvoltage protection function operates when FB terminal voltage exceeds VOVP (=1.2 × VREF) and continues more
than set time in external resistance.

CTL

terminal

>VIHCTL

SS terminal FB terminal

>1.1V(typ)

<1.0V(typ) - Disable OFF

<VILCTL - - Disable OFF

※Overvoltage protection function is enabled when SS terminal voltage of each Ch becomes more than 1.1V (typ) in the

transition to ON control (during soft start).

O from FB terminal and off-latched DC/DC converter

LVP (=0.7 × VREF) and continues more

Table 4 Low voltage protection function

Low voltage

protection function

LVP

<V

>VLVP+VLVP_HYS OFF

Enable

Low voltage

protection operation

ON

Table 5 Overvoltage protection function

Overvoltage

protection function

OVP

>V
<VOVP OFF

Enable

Overvoltage

protection operation

ON

Figure 5-1．Low voltage / overvoltage protection

11 / 14

Overcurrent protection function (OCP)
Overcurrent protection function compared drain voltage (LX terminal voltage) with internal OCP terminal voltage when
internal Nch POWER MOS is ON. When LX terminal voltage becomes lower than OCP terminal voltage, external MOS
would be OFF.

Off latch by overcurrent protection function operates when LX terminal voltage falls below OCP terminal voltage and
continues more than set time in external resistance.

Table 6 overcurrent protection function

CTL

terminal

SS terminal Output current

>VIHCTL >1.1V(typ) >Ilmt

<Ilmt OFF

Overcurrent

protection function

Enable

Overcurrent

protection operation

ON

<1.0V(typ) - Disable OFF

<VILCTL - - Disable OFF

DRV

A

OCP

DRV

B

Rocp

LX

Output
current

Figure 5-2．Overcurrent protection

RT terminal open/short protection function
RT terminal open/shot protection function off-latches all DC/DC converter controller by detecting open/short
condition internally from RT terminal to prevent from output voltage error caused by error oscillation of
internal triangular wave at RT terminal open/short.

RT terminal open/short protection function is regularly enabled after boot-up.
RT terminal open/short protection function operates when error detection condition continues more than set
time in external resistance.

12 / 14

Soft start time-out function
DC/DC converter off-latch-controls when V

does not exceed V

SS

from VSS > V

SSPON

SSSTB+VSSSTB_HYS

after 50msec (typ)

passed from soft start.

Figure 5-3. At soft start time-out

Error detection (off latch) release method
DC/DC converter becomes off latch condition when protection function operates. Off latch can be released by the
following method. DC/DC converter controller of each Ch becomes able to do ON control transition by releasing off latch.

1. Set all Ch CTL terminal voltage as < V

and continue that condition about more than 200usec (typ).

ILCTL

2. Drop down power supply VCC to below 2.7V(TYP).

Error detection time set function
Time from the error detection to the off latch can be set by putting resistance outside between GND and RSET terminal.



3



t

offlatch

1081

Rset setting range
10kΩ≦Rset≦75kΩ
（18usec≦tofflach≦135usec）

sec]u[Rrset. 

13 / 14

y

p

p

（

HTSSOP-B24

<Dimension>

0.1

0.2

±

±

5.6

7.6

1

0.325

0.65

0.05

0.05

1.0Max.

±

±

0.08

0.85

<Tape and Reel information>

Tape

Quantit

7.8

±

0.1

+6

4

−4

1324

0.15

±

0.2

±

1

0.53

+0.05

12

0.17

−0.03

0.08 S

+0.05

0.2

−0.04

M

0.08

Direction
of feed

Unit:mm)

Embossed carrier ta

2000

cs

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)

1234

1234

1234

Reel

1pin

1234

e

1234

1234

※When you order , please order in times the amount of package quantity.

1234

Direction of feed

1234

14 / 14

Catalog No.08T277A '08.8 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.

Thank you for your accessing to ROHM product informations.
More detail product informations and catalogs are available, please contact your nearest sales office.

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Appendix1-Rev2.0