Fujitsu MB3845, MB3842 User Manual

FUJITSU SEMICONDUCTOR

DATA SHEET

DS04-27604-2E

ASSP For Power Supply Applications

Power Management 2-ch Switch IC

MB3842/MB3845

DESCRIPTION

■

The MB3842/3845 is a power management switch with built-in 2-channel low-on resistance (typ. 100mΩ) switch.
Output control is by means of a control signal, and the MB3842 is designed for high-active operation (output on
when EN is Hi), while the MB3845 is designed for low-active operation (output on when EN
To provide adaptability to a variety of operations, the MB3842/3845 features low input voltage (V
operation and stable low-on resistance independent of input voltage. The switching current limit can be set from
100mA to 600mA by using external resistance, and when overcurrent conditions are detected the OC output goes
low to provide an external notification signal.
V

is divided between the two channels, which operate independently of each other.

IN

In addition, an off-state reverse current prevention function is provided to ensure accurate on/off switching action.

is low.)

IN

> 2.5V)

FEATURES

■

• Low on resistance switch (typ. 100mΩ)

• Low input voltage operation (2.5 V to 5.5 V)

• Switch current (max. 0.6 A)

•UVLO :V

• ENABLE :EN threshold EN 1.4V/1.6 V for MB3842, EN 1/2 V

• External setting for soft start time and switch current limit.

• Over-temperature detection (switch latched off), over-current detection (not latched)

• OC pin flag set following overcurrent detection, over-temperature detection, or UVLO detection.

• Reverse current prevention at OFF (V

• Either channel may be operated alone.

PACKAGE

■

threshold 2.3V/2.1 V hysteresis 200 mV

IN

:Power supply current at output off = 0µA EN < 0.8V for MB3842, EN = V

≥ 1.5 V)

IN

20-pin plastic SSOP

(FPT-20P-M03)

for MB3845

IN

for MB3845

IN

MB3842/MB3845

PIN ASSIGNMENT

■

EN1, EN1

SS1

CS1

VIN1

1

2

3

4

SSOP-20P

(FPT-20P-M03)

20

19

18

17

GND

OC1

OUT1

OUT1

VIN1

VIN2

VIN2

CS2

SS2

EN2, EN2

5

6

7

8

9

10

EN Enable

EN Enable SS Slow Start

16

15

14

13

12

11

OUT1

OUT2

OUT2

OUT2

OC2

GND

CS Current Set OC Over Current

The functions of pin 1 and pin 10 differ on the MB3842 and MB3845.
EN for MB3842/EN

for MB3845

2

PIN DESCRIPTION

■

Pin no. Symbol Descriptions

Control signal input pin.

EN

(MB3842)

Set “H” to turn switch on, “L” to turn toff. At 0.8 V or less, the chip is in STBY state
and current consumption is less than 1µA.
“L” level is 1.4V (typ), “H” level is 1.6V (typ), with 200mV (typ) hysteresis.

MB3842/MB3845

1/10

Control signal input pin.
Set “L” to turn switch on, “H” to turn off.

EN

(MB3845)

At “H” level = V
1µA.
Normally used as CMOS inverter input, so that recommended use is “L” level at
GND +0.5V or less, and “H” level is V

Slow start setting pin. Used to adjust the switch on/off timing.

2/9 SS

Add external capacitance to delay operation. Leave open when not in use.
In open mode voltages up to 12 V are present. Care should be taken in mounting
to prevent leakage current generation because high impedance is required.

3/8 CS

Current limit setting pin.
The limit current level is set by connecting this pin to external resistance.

Switch output pin.
An UVLO (V

4/5/6/7 VIN

(typ.) or higher the OC pin v oltage goes to “H” lev el. Also if the V

2.1 V (typ.) or lower the OC output goes to “L” state.
200mV (typ) hysteresis is provided.

11/20 GND Ground pin.

External notification pin.
When the switch is in on mode this pin normally outputs a “H” level signal, but

12/19 OC

changes to “L” level when an overcurrent, overtemperature, or UVLO condition is
detected.
This is an open drain connection, and should be pulled up to high potential using
resistance.

, the chip is in STBY state and current consumption is less than

IN

-0.5V or greater.

IN

power monitor function) is provided so that when VIN reaches 2.3V

IN

voltage drops to

IN

13/14/15
16/17/18

OUT Switching output pin.(N-ch MOSFET source)

3

MB3842/MB3845

BLOCK DIAGRAM (for 1 channel)

■

MB3842

OUT1

SS1

EN1

VIN1

Temperature

protection 1

MB3845

Charge

pump1

OSC1

BGR1

Q

FF1

Over current

detection 1

S

R

+

COMP

−

CS1

+

COMP

−

OC1

OUT1

CS1

OC1

SS1

EN1

VIN1

Charge

pump1

OSC1

BGR1

Temperature

protection 1

Q

FF1

Over current

detection 1

S

R

+

COMP

−

+

COMP

−

4

ABSOLUTE MAXIMUM RATINGS

■

MB3842/MB3845

Parameter Symbol Condition

Unit

Max. Min.

Rating

Input voltage V
ENABLE voltage V
Switch current I
Power dissipation P
Storage temperature T

IN

EN

SW

STG

Ta = +85°C — 216 mW

D

— –0.3 7.0 V
— –0.3 7.0 V
——1.8A

— –55 +125 °C

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.

RECOMMENDED OPERATING CONDITIONS

■

Value

Parameter Symbol Condition

Unit

Min. Typ. Max.

Input voltage V
ENABLE voltage V
Switch current I
SS pin capacitance C
OC sink current I

IN

EN

SW

SS

OCS

VEN ≤ VIN 0—5.5V
VIN = 2.5 V to 5.5 V — — 0.6 A

* — — — 10 nF

VIN = 5.0 V, VOC = 0.4 V 2.0 5.0 — mA

—2.55.05.5V

V

= 5.0 V (ISW = 0.6 A) 1.4 2.0 2.6 kΩ

Current limit
resistance

Operating
temperature

* :For CSS, R

*

R

LIM

T

OP

settings, see “TYPICAL CHARACTERISTICS” and “FUNCTIONAL DESCRIPTION”.

LIM

IN

= 5.0 V (ISW = 0.1 A) 3.6 6.2 9.1 kΩ

V

IN

— –20 — +85 °C

WARNING: The recommended operating conditions are required in order to ensure the normal operation of the

semiconductor device. All of the device's electrical characteristics are warranted when the device is
operated within these ranges.

Always use semiconductor de vices within their recommended operating condition r anges. Oper ation
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 their
FUJITSU representatives beforehand.

5

MB3842/MB3845

ELECTRICAL CHARACTERISTICS (per 1 ch)

■

• MB3842/MB3845 (VIN = 5 V, Ta = +25°C)

Parameter Symbol Condition

Min. Typ. Max.

Value

Unit

Switch resistance R

IN pin input current

I
I

I

V

ISW =0.6A — 100 150 mΩ

ON

ISW = 0 A — 350 550 µA

IN1

ISW = 0.6 A — 1.0 1.5 mA

IN2

EN < 0.8V for MB3842,

IN3

EN

= VIN for MB3845

VIN at OC = L → H 2.1 2.3 2.5 V

IUH

——1.0µA

UVLO threshold

UVLO hysteresis width V

V

I

SWH

IUHY

VIN at OC = H → L 1.9 2.1 2.3 V

IUL

V

= V

IUHY

R

= 2.0 kΩ 0.42 0.6 0.78 A

LIM

IUH

– V

IUL

100 200 300 mV

Switch current limit

I
I

SWL

OCS

R

= 6.2 kΩ 0.06 0.1 0.14 A

LIM

VOC = 0.4 V at OC active 2.0 5.0 — mA

OC sink current

VOC = 5.0 V at OC non-active — — 1.0 µA

LIM

SS pin: Open

ON

OUT pin: 100 kΩ pull down
SS pin: Open

OUT pin: 100 kΩ pull down

— +125 — — °C

— 100 200 µs

—50120µs

Temperature protection (T

)T

j

OUT pin rise time t

OUT pin fall time t

I

OCL

OFF

• MB3842 (V

Parameter Symbol Condition

Min. Typ. Max.

= 5 V, Ta = +25°C)

IN

Value

Unit

I

ENH

VEN = 5 V, ISW = 0 A — 5 10 µA

ENABLE pin input current

ENABLE pin threshold
voltage

ENABLE hysteresis width V

V
V

I

ENL

THEN

TLEN

ENHY

VEN = 0 V, ISW = 0 A — 0.0 — µA

— 1.45 1.60 1.75 V
— 1.25 1.40 1.55 V

V

ENHY

= V

THEN

– V

TLEN

• MB3845 (V

Parameter Symbol Condition

ENABLE

ENABLE

pin input current

pin input voltage

V
V

I
I

ENH

ENL

IHEN

VEN = 5 V, ISW = 0 A — 0.0 — µA
VEN = 0 V, ISW = 0 A — 0.0 — µA

ILEN

—0—0.8V
—3.0—5.0V

6

100 200 300 mV

= 5 V, Ta = +25°C)

IN

Value

Unit

Min. Typ. Max.