Fujitsu MB3842 User manual
DS04-27604-2E
FUJITSU SEMICONDUCTOR
DATA SHEET
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 is low.)
To provide adaptability to a variety of operations, the MB3842/3845 features low input voltage (VIN >2.5V)
operation and stable low-on resistance independent of input voltage. The switching current limit can be set from
100mAto600mAbyusingexternalresistance,andwhenovercurrentconditionsaredetectedtheOCoutputgoes
low to provide an external notification signal.
VIN is divided between the two channels, which operate independently of each other.
In addition, an off-state reverse current prevention function is provided to ensure accurate on/off switching action.
■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
IN threshold 2.3V/2.1 V hysteresis 200 mV
• ENABLE :EN threshold EN 1.4V/1.6 V for MB3842, EN 1/2 VIN for MB3845
:Power supply current at output off = 0µA EN < 0.8V for MB3842, EN =VIN for MB3845
• 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 (VIN ≥1.5 V)
• Either channel may be operated alone.
■PACKAGE
20-pin plastic SSOP
(FPT-20P-M03)
2
MB3842/MB3845
■PIN ASSIGNMENT
20
19
18
17
16
15
14
13
12
11
GND
OC1
OUT1
OUT1
OUT1
OUT2
OUT2
OUT2
OC2
GND
1
2
3
4
5
6
7
8
9
10
EN1, EN1
SS1
CS1
VIN1
VIN1
VIN2
VIN2
CS2
SS2
EN2, EN2
SSOP-20P
(FPT-20P-M03)
EN Enable
CS Current Set OC Over Current
EN Enable SS Slow Start
The functions of pin 1 and pin 10 differ on the MB3842 and MB3845.
EN for MB3842/EN for MB3845
3
MB3842/MB3845
■PIN DESCRIPTION
Pin no. Symbol Descriptions
1/10
EN
(MB3842)
Control signal input pin.
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.
EN
(MB3845)
Control signal input pin.
Set “L” to turn switch on, “H” to turn off.
At “H” level = VIN, the chip is in STBY state and current consumption is less than
1µA.
Normally used as CMOS inverter input, so that recommended use is “L” level at
GND +0.5V or less, and “H” level is VIN -0.5V or greater.
2/9 SS Slow start setting pin. Used to adjust the switch on/off timing.
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.
4/5/6/7 VIN
Switch output pin.
An UVLO (VIN power monitor function) is provided so that when VIN reaches 2.3V
(typ.) or higher the OC pin voltage goes to “H” level. Also if the VIN voltage drops to
2.1 V (typ.) or lower the OC output goes to “L” state.
200mV (typ) hysteresis is provided.
11/20 GND Ground pin.
12/19 OC
External notification pin.
When the switch is in on mode this pin normally outputs a “H” level signal, but
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.
13/14/15
16/17/18 OUT Switching output pin.(N-ch MOSFET source)
4
MB3842/MB3845
■BLOCK DIAGRAM (for 1 channel)
SS1
EN1
VIN1
OSC1
BGR1
+
−
COMP
FF1
QS
R
OC1
OUT1
CS1
+
−
COMP
MB3842
SS1
EN1
VIN1
OSC1
BGR1
+
−
COMP
FF1
QS
R
OC1
OUT1
CS1
+
−
COMP
MB3845
Temperature
protection 1
Charge
pump1 Over current
detection 1
Charge
pump1 Over current
detection 1
Temperature
protection 1
5
MB3842/MB3845
■ABSOLUTE MAXIMUM RATINGS
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
* :For CSS, RLIM settings, see “TYPICAL CHARACTERISTICS” and “FUNCTIONAL DESCRIPTION”.
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 devices within their recommended operating condition ranges. 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 their
FUJITSU representatives beforehand.
Parameter Symbol Condition Rating Unit
Max. Min.
Input voltage VIN — –0.3 7.0 V
ENABLE voltage VEN — –0.3 7.0 V
Switch current ISW ——1.8A
Power dissipation PDTa = +85°C — 216 mW
Storage temperature TSTG — –55 +125 °C
Parameter Symbol Condition Value Unit
Min. Typ. Max.
Input voltage VIN —2.55.05.5V
ENABLE voltage VEN VEN ≤VIN 0—5.5V
Switch current ISW VIN = 2.5 V to 5.5 V — — 0.6 A
SS pin capacitance CSS* — — — 10 nF
OC sink current IOCS VIN = 5.0 V, VOC = 0.4 V 2.0 5.0 — mA
Current limit
resistance RLIM*VIN = 5.0 V (ISW = 0.6 A) 1.4 2.0 2.6 kΩ
VIN = 5.0 V (ISW = 0.1 A) 3.6 6.2 9.1 kΩ
Operating
temperature TOP — –20 — +85 °C
6
MB3842/MB3845
■ELECTRICAL CHARACTERISTICS (per 1 ch)
• MB3842/MB3845 (VIN = 5 V, Ta = +25°C)
• MB3842 (VIN = 5 V, Ta = +25°C)
• MB3845 (VIN = 5 V, Ta = +25°C)
Parameter Symbol Condition Value Unit
Min. Typ. Max.
Switch resistance RON ISW =0.6A — 100 150 mΩ
IN pin input current
IIN1 ISW = 0 A — 350 550 µA
IIN2 ISW = 0.6 A — 1.0 1.5 mA
IIN3 EN < 0.8V for MB3842,
EN =VIN for MB3845 ——1.0µA
UVLO threshold VIUH VIN at OC = L →H 2.1 2.3 2.5 V
VIUL VIN at OC = H →L 1.9 2.1 2.3 V
UVLO hysteresis width VIUHY VIUHY = VIUH – VIUL 100 200 300 mV
Switch current limit ISWH RLIM = 2.0 kΩ0.42 0.6 0.78 A
ISWL RLIM = 6.2 kΩ0.06 0.1 0.14 A
OC sink current IOCS VOC = 0.4 V at OC active 2.0 5.0 — mA
IOCL VOC = 5.0 V at OC non-active — — 1.0 µA
Temperature protection (Tj)T
LIM — +125 — — °C
OUT pin rise time tON SS pin: Open
OUT pin: 100 kΩpull down — 100 200 µs
OUT pin fall time tOFF SS pin: Open
OUT pin: 100 kΩpull down —50120µs
Parameter Symbol Condition Value Unit
Min. Typ. Max.
ENABLE pin input current IENH VEN = 5 V, ISW = 0 A — 5 10 µA
IENL VEN = 0 V, ISW = 0 A — 0.0 — µA
ENABLE pin threshold
voltage VTHEN — 1.45 1.60 1.75 V
VTLEN — 1.25 1.40 1.55 V
ENABLE hysteresis width VENHY VENHY = VTHEN – VTLEN 100 200 300 mV
Parameter Symbol Condition Value Unit
Min. Typ. Max.
ENABLE pin input current IENH VEN = 5 V, ISW = 0 A — 0.0 — µA
IENL VEN = 0 V, ISW = 0 A — 0.0 — µA
ENABLE pin input voltage VILEN —0—0.8V
VIHEN —3.0—5.0V
7
MB3842/MB3845
■DIAGRAM
(Continued)
VIN
EN
EN
VOUT
IOUT
OC
SW OFF
Overcurrent does not occur
SW ON SW ON
5 V
Hi
Low
5 V
5 V
• Normal operation
SW ONSW ONSW ON
2.3 V
2.1 V
5 V
Hi
Low
5 V
5 V
= 0 V
VIN
EN
EN
V
OUT
I
OUT
OC
Overcurrent does not occur
•AtV
IN fall
Note: The OC pin should be pulled up using a separate power supply and resistance.
(This illustration shows pull-up with a separate 5V source.)
8
MB3842/MB3845
(Continued)
SW ON OFF ON OFF
VIN
EN
EN
VOUT
IOUT
OC
5 V
Hi
Low
5 V
5 V
= 0 V
• At overcurrent detection
SW ON
Over-temperature corrected
Over-temperature
occurs
SW OFF
VIN
EN
EN
V
OUT
I
OUT
OC
5 V
Hi
Low
5 V
5 V
= 0 V
Overcurrent does not
occur
Latch set Latch released
• At over-temperature occurrence
Note: The OC pin should be pulled up using a separate power supply and resistance.
(This illustration shows pull-up with a separate 5V source.)
9
MB3842/MB3845
■TYPICAL CHARACTERISTICS
(Continued)
VIN = 5.0 V
VIN = 3.3 V
VIN = 2.5 V
10
1
0.1
0.01100 1000 10000 100000
RLIM (Ω)
ISW(A)
•R
LIM vs. limit current characteristics
VIN = 5.0 V
VIN = 3.3 V
VIN = 2.5 V
100
10
1
0.1 10 100 1000 10000 100000
CSS (pF)
tON(ms)
•C
SS vs. TON (SS) characteristics
ThesearethelimitingvaluecharacteristicsforCSpin-to-GND
external resistance and output current (OC flag).
There are the characteristics for SS pin-to-GND external
capacitance and output ON time.
10
MB3842/MB3845
(Continued)
(Continued)
150
140
130
120
110
100
90
80
70
60
50−60 −40 −20 0 20 40 60 80 100 120
at 0.1 A
at 0.6 A
at 1 A
−40 °C
25 °C
100 °C
150
140
130
120
110
100
90
80
70
60
50 234567
• SW resistance vs. temperature characteristics
• Temperature-dependedSWresistancevs.VIN (V)characteristics
SW resistance (mΩ)
Temperature Ta (°C)
SW resistance (mΩ)
VIN voltage (V)
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