Datasheet B3800P, B3800M Datasheet (BAYLI)

Bay Linear

Inspire the Linear Power

Switching Regulator Controller

Step Up Low Voltage (BIPOLAR)

Description

The Bay Linear B3800 series is monolithic control circuit
containing the primary functions required for DC-to-DC
converters. This device is design for low voltage applications
incorporating a soft start function and sort circuit detection
function. The device has a low minimum operating voltage of

1.8V and is ideal for the power supply of battery-operated
electronic equipments.

This series was specially designed to be incorporated in Step­Down and voltage-inverting applications with a minimum
number of external components.

The B3800 is offer in 8-pin DIP or Surface mount package.

Pin Connection

8-Pin Su rface Mount

8-

8-Pin Su rface Mount

8-

-IN

-IN

SCP 2

SCP 2

1

1

1

1

2

2

8

8

8

8

FB

FB

7

7

7

7

OSC

OSC

BR/CTL

BR/CTL

Vcc

Vcc

3

3

3

3

4

4

4

4

6

6

6

6

GND

GND

5

5

5

5

OUT

OUT

Features

• Wide operation from…………... 1.8 to 15V

• Low Standby Current……………….. 1 µA

• Low Current Consumption……… 5.5mA

• high Speed Operation ……………. 1MHz

Incorporates soft start circuit

•

•

Incorporates a stand-by function

Incorporate a times-latch short circuit

•

detection circuit (SCP)

• Totem-pole type output with adjustable

on/off current (for NPN transistor)

• The error amplifier gain is set inside the

IC, so peripheral components are
minimized.

• Direct Replacement for MB3800

Applications

• Digital Camera

• MP3

• Low Battery Operating Applications

Ordering Information

SO-8
8-pin

B3800M B3800P

P-DIP

8-pin

Operating

Temp. Range

-40°C to 85°C

B3800

Bay Linear, Inc

To p V i e w

To p V i e w

2418 Armstrong Street, Livermore, CA 94550 Tel: [phone], Fax: [phone] www.baylinear.com

B3800

PIN Description

Pin No. Symbol I/O Description

1 -IN I
2 SCP ­3 V

CC

4 BR/CTL I
5 V

OUT

6 GND ­7 OSC ­8 FB O

Error amplifier inverting
Soft start and SCP setting capacitor connection pin
Power supply pin

-

Output current setting and control pin
Totem-pole type output pin

O

Ground pin
Capacitor and resistor connection pin setting the oscillation frequency
Error amplifier output pin

Absolute Maximum Rating

Parameter Symbol Value Unit

Supply Voltage V
Output source current I
Output sink current I
Allowable dissipation

Operating temperature T
Storage temperature Tstg -55 to +125

WARNING: Semiconductor devices can be permanently damaged by application of stress (voltage, current, temperature, etc.) in
excess of absolute maximum ratings. Do not exceed these ratings.

SOP-8, Ta≤+25°C

SOP-8, T

SSOP-8, T

CC

+

O

-

O

≤+25°C

a

≤+25°C 580 mW

a

op

16 V

-50 mA
50 mA

570 mW
430 mW

-30 to +85

°C
°C

Recommended Operating Condition

Parameter Symbol

Power Supply Voltage V
Error amplifier input voltage V
BR/CTL pin input voltage V
Output source current I
Output sink current I
SCP pin capacitance C
Phase compensation capacitance C
Output current setting resistance
Timing resistance
Timing Capacitance C
Oscillation frequency f
Operation temperature

WARNING: Recommended operating conditions are normal operating ranges for the semiconductor device. All the device’s
electrical characteristics are warranted when operated within these ranges. Always use semiconductor devices within the
recommended operating conditions. Operation outside these ranges may adversely affect reliability and could result in device
failure.

No warranty is made with respect to uses, operating conditions, or combinations not represented on the data sheet. Users
considering application outside the listed conditions are advised to contact Bay Linear.

R
R

OSC

T

CC

I

BR

+

O

-

O

PE

P

B

T

T

OP

Min Typ. Max.

1.8 - 15 V

-.0.2 - 1.0 V

-0.2 - V

-40 - - mA

- - 40 mA

- 0.1 - µF

- 0.1 - µF

150 390 5000

1.0 3.0 10.0

100 270 10000 pF

10 500 1000 kHz

-30 +30 +85

Values

CC

Unit

V

Ω

kΩ

°C

Bay Linear, Inc

2418 Armstrong Street, Livermore, CA 94550 Tel: [phone], Fax: [phone] www.baylinear.com

Electrical Characteristics

Parameter Symbol Conditions

Circuit to Prevent
Malfunction at low input
voltage (U.V.L.O.)

Soft Start

(OSC)

Sawtooth wave oscillator
(OSC)

Error amplifier

Idle period adjustable
section

Output section

Output current setting
section/ Control section

Entire device

Reset Voltage V

Threshold voltage

Changing current

Voltage at soft start
completion
Charging current I
Threshold voltage V

Oscillation freq. f

Frequency input
stability
Frequency variation
with temperature
Input threshold
voltage
VTinput stability V
VT variation with
temperature
Input bias current I
Voltage gain

Frequency bandwidth

Maximum output
voltage range
Output source current I
Output sink current I
Maximum duty cycle

Output voltage

Output source current I
Output sink current I
Pull down resistance R
Pin Voltage V
Input off condition I
Input on condition I
Pin current range I

Stand-by current I

Average supply
current

Value

B3800

Unit

Min. Typ. Max.

R

V

TH

I

CS

V

TS

cpc

PC

ocs

f

dv

f

dt

V

T

Tdv

V

TDT

B

A

V

BW A

+

V

OM

-

V

OM

+

OM

_

OM

t

DUTY

V

OH1

V

OH2

V

OL1

V

OL2

+

O

-

O

O

BR

OFF

ON

BR

CCB

I

CC

-

V

=0V 0.7 0.8 0.9 V

SCP

V

=0V -1.5 -1.0 -0.7 µA Short Circuit detection

SCP

- 0.7 0.8 0.9 V

RT=3.0kΩ, CT=270pF

VCC=2V to 15V - 2 10 %

Ta=-30°C to +85°C

VFB=450mV 480 500 520 mV

VCC= 2V to 15V - 5 20 mV

Ta= -30°C to +85°C

VIN=0V -1.0 -0.2 1.0 µA

- 70 100 145

=0dB - 6 -

V

-

VFB=0.45V

RT=3.0kΩ, CT=270pF
V

=0.8V

FB

RB=390Ω, IO= -15mA
RB=750Ω, IO= -10mA,

=1.8V

V

CC

RB=390Ω, IO=15mA
RB=750Ω, IO=10mA,
V

=1.8V

CC

RB=390Ω, VCC=0.9V
RB=390Ω, VCC=0.3V

- 20 30 40

RB=390Ω,

-

BR/CTL pin open or
V

cc

RB=390Ω,

- - 0.9 V

1.1 1.3 1.5 V

-1.5 -1.0 -0.7 µA

400 500 600

kH

z

- 5 - %

- 1 - %

V/

V

M

Hz

0.78 - 0.87

0.05

-

0.2

V

- -40 -24 µA

24 40 - µA

65 75 85 %

1.0 1.2 - V

0.8 1.0 - V

- 0.1 0.2 V

- 0.1 0.2 V

- -30 -20 mA

30 60 - mA

kΩ

0.2 0.3 0.4 V

-20 - 0 µA

- - -45 µA

-1.8 - -0.1 mA

- - 1 mA

- 5.5 9.3 mA

Bay Linear, Inc

2418 Armstrong Street, Livermore, CA 94550 Tel: [phone], Fax: [phone] www.baylinear.com

TIMMING DIAGRAM

BLOCK DIAGRAM

B3800

Bay Linear, Inc

2418 Armstrong Street, Livermore, CA 94550 Tel: [phone], Fax: [phone] www.baylinear.com

Typical Characteristics

B3800

Bay Linear, Inc

2418 Armstrong Street, Livermore, CA 94550 Tel: [phone], Fax: [phone] www.baylinear.com

Typical Characteristics (continued)

B3800

Bay Linear, Inc

2418 Armstrong Street, Livermore, CA 94550 Tel: [phone], Fax: [phone] www.baylinear.com

Typical Characteristics (continued)

B3800

Bay Linear

Bay Linear, Inc

B3800

2418 Armstrong Street, Livermore, CA 94550 Tel: [phone], Fax: [phone] www.baylinear.com

Application Descriptions

Power Supply Control Function

Stand- by mode (supply current 1 mA or less) can be set by
connecting the BR/ CTL pin (pin 4) to VCC or by making the
pin open circuit.

Switching Regulator Function

Reference voltage circuit
The reference voltage circuit generates a temperature­compensated reference voltage (@1.25V) from voltage
supplied from the power supply pin (pin 3). In addition to
providing the reference voltage for the switching regulator, the
circuit also sets the idle period.

Sawtooth wave oscillator
The sawtooth oscillator generates a sawtooth wave (up to 1
MHz) that is stable with respect to the supply voltage and
temperature. The capacitor and resistor that set the oscillation
frequency are connected to the OSC pin (pin 7).

Error amplifier (Error Amp.)
The error amplifier detects the output voltage of the switching
regulator and outputs the PWM control signal. The voltage
gain is fixed, and connecting a phase compensation capacitor
to the FB pin (pin 8) provides stable phase compensation for
the system.

PWM comparator (PWM Comp.)

The voltage comparator has one inverting and three non­inverting inputs. The comparator is a voltage/ pulse width
converter that controls the ON time of the output pulse
depending on the input voltage. The output level is high (H)
when the sawtooth wave is lower than the error amplifier
output voltage, soft start setting voltage, and idle period setting
voltage.

Output circuit
The output circuit has a totem pole type configuration and
can drive an external NPN transistor directly. The value
of the ON/ OFF current can be set by a resistor connected
to the BR/ CTL pin (pin 4).

Other Functions

Soft start and short circuit detection

Soft start operation is set by connecting capacitor CPE to
the SCP pin (pin 2). Soft start prevents a current spike on
start- up.

On completion of soft start operation, the SCP pin (pin 2)
stays low and enters the short circuit detection wait state.
When an output short circuit occurs, the error amplifier
output is fixed at VOM+ and capacitor CPE starts
charging. After charging to approximately 0.8 V, the
output pin (pin 5) is set low and the SCP pin (pin 2) stays
low.

Once the protection circuit operates, the circuit can be
restored by resetting the power supply. (See “n HOW TO
SET THE TIME CONSTANT FOR SOFT START AND
SHORT CIRCUIT DETECTION”.)

Circuit to prevent malfunction at low input voltage

Transients when powering on or instantaneous glitches in
the supply voltage can lead to malfunction of the control
IC and cause system damage or failure. The circuit to
prevent malfunction at low input voltage detects a low
input voltage by comparing the supply voltage to the
internal reference voltage. On detection, the circuit fixes
the output pin to low.

The system recovers when the supply voltage rises back
above the threshold voltage of the malfunction prevention
circuit.

B3800

Bay Linear, Inc

2418 Armstrong Street, Livermore, CA 94550 Tel: [phone], Fax: [phone] www.baylinear.com

HOW TO SET THE TIME CONSTANT FOR SOFT

START AND SHORT CIRCUIT DETECTION

Soft Start

At power on, the capacitor CPE connected to the SCP pin
starts charging. The PWM comparator compares the soft start
setting voltage as a proportion of the voltage at the SCP pin
with the sawtooth waveform. The comparison controls the ON
duty of the OUT pin, causing the soft start operation. On
completion of soft start operation, the voltage at the SCP pin
stays low, the soft start setting voltage stays high, and the
circuit enters the output short circuit detection wait state. Soft
start time (The time until the output ON duty reaches
approximately 50%) tS [s] @ 0.35 ´ CPE [mF]

APPLICATION DIAGRAM

B3800

Short Circuit Protection

If the switching regulator output suddenly drops due to
load effect, the error amplifier output (FB pin) is fixed at
VOM + and capacitor CPE starts charging. When the
voltage at the SCP pin reaches approximately 0.8V, the
output pin is set low and the SCP pin stays low. Once the
protection circuit operates, the circuit can be restored by
resetting the power supply. • Short circuit detection time

[s] @ 0.8 ´ CPE [mF]

T

PE

Bay Linear, Inc

B3800

2418 Armstrong Street, Livermore, CA 94550 Tel: [phone], Fax: [phone] www.baylinear.com

B3800

8 pin SOIC

Pin 1

1.27 (0.50)
BSC

5.0 (0.197)

4.8 (0.188)

0.56 (0.022)

0.49 (0.019)

0.45 (0.018)

0.35 (0.014)

Advance Information- These data sheets contain descriptions of products that are in development. The specifications are based on the engineering calculations,
computer simulations and/ or initial prototype evaluation.

Preliminary Information- These data sheets contain minimum and maximum specifications that are based on the initial device characterizations. These limits are
subject to change upon the completion of the full characterization over the specified temperature and supply voltage ranges.

The application circuit examples are only to explain the representative applications of the devices and are not intended to guarantee any circuit
design or permit any industrial property right to other rights to execute. Bay Linear takes no responsibility for any problems related to any
industrial property right resulting from the use of the contents shown in the data book. Typical parameters can and do vary in different
applications. Customer’s technical experts must validate all operating parameters including “ Typical” for each customer application.

LIFE SUPPORT AND NUCLEAR POLICY

Bay Linear products are not authorized for and should not be used within life support systems which are intended for surgical
implants into the body to support or sustain life, in aircraft, space equipment, submarine, or nuclear facility applications without
the specific written consent of Bay Linear President.

Bay Linear, Inc

2418 Armstrong Street, Livermore, CA 94550 Tel: [phone], Fax: [phone] www.baylinear.com

4.0 (0.158)

3.8 (0.150)

1.75 (0.069)

1.35 (0.053)

0.78 (0.031)

0.61 (0.024)

0.20 (0.008)

0.10 (0.004)

5.2 (0.205)

4.6 (0.181)

0.37 (0.015)
BSC

0.22 (0.009)

0.19 (0.007)

6.2 (0.244)

5.8 (0.228)

°

45

7

0.77 (0.030)

0.64 (0.025)

°

(4 PLCS)

3°-6

7°(4 PLCS)

°