ROHM BD8301MUV Technical data

Single-chip Type with Built-in FET Switching Regulator Series

High-efficiency Step-up/down
Switching Regulator
with Built-in Power MOSFET

BD8301MUV

●General Description

ROHM’s highly-efficient step-up/down switching regulator BD8301MUV produces step-up/down output including 3.3 V from
1 cell of lithium battery with just one coil.
This IC adopts an original step-up/down drive system and creates a higher efficient power supply than conventional
Sepic-system or H-bridge system switching regulators.

●Features

1) Highly-efficient step-up/down DC/DC converter to be constructed just with one inductor.

2) Input voltage 2.5 V - 5.5 V

3) Output current 1 A at 3.3 V
800 mA at 5.0 V

4) Incorporates soft-start function.

5) Incorporates timer latch system short protecting function.

6) High heat radiation surface mounted package VQFN020V4040

●Application

General portable equipment like portable audio or DSC/DVC

●Absolute Maximum Ratings

Parameter Symbol Ratings Unit

Maximum applied power voltage Vcc,PVCC 7.0 V

Maximum input current Iinmax 2.0 A

Maximum input voltage

Power dissipation Pd 700 mW

Operating temperature range Topr -25 to +85 ºC

Storage temperature range Tstg -55 to +150 ºC

Junction temperature Tjmax 150 ºC

*1 When installed on a 70.0 mm × 70.0 mm × 1.6 mm glass epoxy board. The rating is reduced by 5.6 mW/°C at Ta = 25°C or more.

●Operating Conditions (Ta = 25°C)

Parameter Symbol

Power supply voltage Vcc 2.5 to 5.5 V

Output voltage OUT 2.8 to 5.2 V

Lx1 7.0 V

Lx2 7.0 V

Voltage range Unit

No.09027ECT07

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1/13

2009.09 - Rev.C

BD8301MUV

●Electrical Characteristics

(Unless otherwise specified, Ta = 25 °C, VCC = 3.7 V)

Parameter Symbol

[Low voltage input malfunction preventing circuit]

Detection threshold voltage VUV - 2.25 2.45 V Vcc monitor
Hysteresis range ΔVUVhy 50 100 150 mV

[Oscillator]
Oscillation frequency fosc 0.8 1.0 1.2 MHz RT=47kΩ

[Error AMP]

INV threshold voltage VINV 0.790 0.800 0.810 V

Input bias current IINV -50 0 50 nA Vcc=7.0V , VINV=3.5V
Soft-start time Tss 0.6 1.00 1.4 msec RT=47kΩ
Output source current IEO 10 20 30 μA VINV=0.5V , VFB =1.5V

Output sink current IEI 0.7 1.5 3.0 mA VINV=1.1V , VFB =1.5V

[PWM comparator]

LX1 Max Duty Dmax1 - - 100 %

LX2 Max Duty Dmax2 77 85 93 %

[Output]
LX1 PMOS ON resistance RON1p - 120 200 mΩ VGS=3.0V
LX1 NMOS ON resistance RON1n - 100 160 mΩ VGS=3.0V
LX2 PMOS ON resistance RON2p - 120 200 mΩ VGS=3.0V
LX2 NMOS ON resistance RON2n - 100 160 mΩ VGS=3.0V
LX1 leak current I leak1 -1 0 1 μA
LX2 leak current I leak2 -1 0 1 μA

[STB]

STB pin ontrol voltage

STB pin pull-down resistance RSTB 250 400 700 kΩ

[Circuit current]

Standby current

Circuit current at operation VCC Icc1 - 500 750 μA VINV=1.2V

Circuit current at operation PVCC Icc2 - 10 20 μA VINV=1.2V

Operation VSTBH 1.5 - 5.5 V

No-operation VSTBL -0.3 - 0.3 V

VCC pin ISTB1 - - 1 μA
PVCC pin ISTB2 - - 1 μA
VOUT pin ISTB3 - - 1 μA

Target Value

Min Typ Max

Unit Conditions

Technical Note

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2/13

2009.09 - Rev.C

BD8301MUV

●Description of Pins

PVCC

15 14 13 12 11

PGND Lx1

PVCC

VCC

STB

RT

16

17

18

19

20

10

PGND

9

8

Lx2

7

VOUT

6

Fig.1 Pin layout

12345

FB

INV

VOUT

GND

Pin No. Pin Name Function

1 FB

2 INV

3～4
5～6 VOUT
7～8 Lx2

9～12 PGND
13～14 Lx1
15～17

18 VCC

19 STB

20 RT

●Block Diagram

STB

RT

VCC

STBY_IO

GND

q

FB

ERROR_AMP

INV

VREF

Soft
Start

+-+

OSC

Reference

VREF

FB H

STOP

CONTROL

DRIVER

PWM

PRE

UVLO

SCP

16000 ｃount

TIMMING

CONTROL

TIMMING

CONTROL

DRIVER

VOUT

LX2

Fig.2 Block diagram

PVCC

PRE

GND

PVCC

PRE

DRIVER

PRE

DRIVER

Technical Note

Error AMP output terminal

Error AMP input terminal

Ground terminal

Output voltage terminal

Output side coil connecting terminal

Power transistor ground terminal

Input side coil connecting terminal

DC/DC converter input terminal
Control part power supply input

terminal
ON/OFF terminal

Oscillation frequency set terminal

LX1

PGND

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3/13

2009.09 - Rev.C

BD8301MUV

●Description of Blocks

1.VREF
This block generates ERROR AMP reference voltage.
The reference voltage is 0.8 V.

2.UVLO
Circuit for preventing low voltage malfunction
Prevents malfunction of the internal circuit at activation of the power supply voltage or at low power supply voltage.
Monitors VCC pin voltage to turn off all output FET and DC/DC converter output when VCC voltage is lower than 2.2 V,
and reset the timer latch of the internal SCP circuit and soft-start circuit.

3.SCP
Timer latch system short-circuit protection circuit
When the INV pin is the set 0.8 V or lower voltage, the internal SCP circuit starts counting.
The internal counter is in synch with OSC; the latch circuit activates after the counter counts about 16000 oscillations to
turn off DC/DC converter output (about 16 msec when RT = 47kΩ).
To reset the latch circuit, turn off the STB pin once. Then, turn it on again or turn on the power supply voltage again.

4.OSC
Oscillation circuit to change frequency by external resistance of the RT pin (20 pin).
When RT = 47 kΩ, operation frequency is set at 1 MHz.

5.ERROR AMP
Error amplifier for detecting output signals and output PWM control signals
The internal reference voltage is set at 0.8 V.

6.PWM COMP
Voltage-pulse width converter for controlling output voltage corresponding to input voltage
Comparing the internal SLOPE waveform with the ERROR AMP output voltage, PWM COMP controls the pulse width
and outputs to the driver.
Max Duty and Min Duty are set at the primary side and the secondary side of the inductor respectively, which are as
follows:
Primary side (Lx1) Max Duty : 100 %,
Min Duty : 0 %
Secondary side (Lx2) Max Duty : 100 %,
Min Duty : About 15 %

7.SOFT START
Circuit for preventing in-rush current at startup by bringing the output voltage of the DC/DC converter into a soft-start
Soft-start time is in synch with the internal OSC, and the output voltage of the DC/DC converter reaches the set voltage
after about 1000 oscillations (About 1 msec when RT = 47 kΩ).

8.PRE DRIVER
CMOS inverter circuit for driving the built-in Pch/Nch FET
Dead time is provided for preventing feedthrough during switching.
The dead time is set at about 15 nsec for each individual SWs.

9. STBY_IO
Voltage applied on STB pin (19 pin) to control ON/OFF of IC
Turned ON when a voltage of 1.5 V or higher is applied and turned OFF when the terminal is open or 0 V is applied.
Incorporates approximately 400 kΩ pull-down resistance.

10. Pch/Nch FET SW
Built-in SW for switching the coil current of the DC/DC converter. Pch FET is about 120 mΩ and Nch is 100 mΩ.
Since the current rating of this FET is 2 A, it should be used within 2 A in total including the DC current and ripple current
of the coil.

Technical Note

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4/13

2009.09 - Rev.C

BD8301MUV

●Reference Data

(Unless otherwise specified, Ta = 25°C, VCC = 3.7 V)

0.810

0.805

0.800

VCC=3.7V

INV THRESHOLD [V]

VCC=2.4V

0.795

0.790

-50 0 50 100 150

TEMPERATURE [℃]

Fig.3 INV threshold

VCC=5.5V

VCC=7.0V

1.20

1.15

1.10

1.05

1.00

0.95

0.90

FREQUENCY [MHz]

0.85

0.80

23456

VCC [℃]

Fig.6 Oscillation frequency

(power supply property)

0

INV=0.5V

-5

-10

-15

-20

-25

-30

FB SOURCE CURRENT [uA]

-35

-40

0.0 0.5 1.0 1.5 2.0

FB VOLTAGE [V]

Fig.9 FB source current

0.810

UVLO

0.805

0.800

INV THRESHOLD [V]

0.795

0.790

0.0 2.0 4.0 6.0 8.0

VCC [V]

Fig.4. INV threshold (power supply property)

2.6

2.5

2.4

2.3

2.2

2.1

2.0

UVLO THRESHOLD [V]

1.9

1.8

-50 0 50 100 150

TEMPARATURE [℃]

RESET

DETECT

Fig.7 UVLO threshold

300

Io=500mA

250

VCC=2.0V

200

150

100

ON RESISTANCE [mΩ]

50

0

-60 - 10 40 90 140

VCC=3.0V

VCC=3.7V

TEMPERATURE [℃]

VCC=6.0V

Fig.10 Lx1 Pch FET ON resistance

Technical Note

1.20

1.15

1.10

1.05

1.00

0.95

0.90

FREQUENCY [MHz]

0.85

0.80

-50 0 50 100 150

TEMPERATURE [℃]

Fig.5 Oscillation frequency

2.0

INV=1.1V

1.8

1.6

1.4

1.2

1.0

0.8

0.6

FB SINK CURRENT [mA]

0.4

0.2

0.0

01234

300

250

200

150

100

ON RESISTANCE [mΩ]

50

0

-60 - 10 40 90 140

Fig.11 Lx1 Nch FET ON resistance

FB VO LTAGE [V]

Fig.8 FB sink current

Io=500mA

VCC=3.7V

VCC=2.0V

VCC=3.0V

TEMPERATURE [℃]

VCC=6.0V

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5/13

2009.09 - Rev.C