FUJITSU SEMICONDUCTOR
DATA SHEET
DS04-27706-2E
ASSP For Power Supply Applications (Secondary battery)
DC/DC Converter IC for Charging
MB3878
■ DESCRIPTION
The MB3878 is a DC/DC converter IC suitable for down-conversion, using pulse-width (PWM) charging and
enabling output voltage to be set to any desired level from one cell to four cells.
These ICs can dynamically control the secondary battery’s charge current by detecting a voltage drop in an AC
adaptor in order to keep its power constant (dynamically-controlled charging).
The charging method enables quick charging, for example, with the AC adaptor during operation of a notebook PC
The MB3878 provides a broad power supply voltage range and low standby current as well as high efficiency,
making it ideal for use as a built-in charging device in products such as notebook PC.
This product is covered by US Patent Number 6,147,477.
■ FEATURES
• Detecting a voltage drop in the AC adaptor and dynamically controlling the charge current
(Dynamically-controlled charging)
• Output voltage setting using external resistor : 1 cell to 4 cells
• High efficiency
: 94 %
• Wide range of operating supply voltages : 7 V to 25 V
• Output voltage setting accuracy : 4.2V ± 0.8% (per cell)
• Built-in frequency setting capacitor enables frequency setting using external resistor only
• Oscillator frequency range : 100kHz to 500kHz
(Continued)
■ PACKAGE
24-pin plastic SSOP
(FPT-24P-M03)
MB3878
■ PIN DESCRIPTION
Pin No.
Symbol
−INC2
OUTC2
+INE2
−INE2
FB2
I/O
I
Descriptions
1
2
Current detection amplifier (Current Amp. 2) input pin.
Current detection amplifier (Current Amp. 2) output pin.
Error amplifier (Error Amp. 2) non-inverted input pin.
Error amplifier (Error Amp. 2) inverted input pin.
Error amplifier (Error Amp. 2) output pin.
O
I
3
4
I
5
O
O
O
I
6
VREF
FB1
Reference voltage output pin.
7
Error amplifier (Error Amp. 1) output pin.
8
−INE1
+INE1
OUTC1
Error amplifier (Error Amp. 1) inverted input pin
Error amplifier (Error Amp. 3) non-inverted input pin.
Current detection amplifier (Current Amp. 1) output pin.
9
I
10
O
With IC in standby mode, this pin is left open to prevent loss of current
through output voltage setting resistance. Set CTL pin to “H” level and
OUTD pin to “L” level.
11
OUTD
O
12
13
−INC1
+INC1
I
I
Current detector amplifier (Current Amp. 1) input pin.
Current detector amplifier (Current Amp. 1) input pin.
Power supply control pin.
Setting the CTL pin low places the IC in the standby mode.
14
CTL
I
15
16
17
18
19
20
21
22
23
24
FB3
−INE3
RT
O
I
Error amplifier (Error Amp. 3) output pin.
Error amplifier (Error Amp. 3) inverted input pin.
Triangular-wave oscillation frequency setting resistor connection pin.
Power supply pin for reference power supply and control circuit.
Power supply pin for FET drive circuit (VH = Vcc − 5 V).
High-side FET gate drive pin.
VCC
VH
O
O
OUT
VCC (O)
CS
Output circuit power supply pin.
Soft-start capacitor connection pin.
GND
+INC2
Ground pin.
I
Current detection amplifier (Current Amp. 2) input pin.
3
MB3878
■ BLOCK DIAGRAM
8
−INE1
OUTC1
+INC1
10
13
<Current Amp.1>
<Error
Amp.1>
−
VREF
+
× 25
−
12
−INC1
+
21 VCC (O)
9
7
+INE1
<PWM Comp.>
<OUT>
+
+
+
−
FB1
20
Drive
OUT
4
−INE2
2
OUTC2
<Error
<Current Amp.2>
VCC
VREF
Amp.2>
24
+
× 25
−
+INC2
−
19
VH
Bias
Voltage
<VH>
1
3
−INC2
+INE2
+
(VCC − 5 V)
FB2 5
2.5 V
1.5 V
<UVLO>
VCC
<Error
Amp.3>
VREF
(VCC UVLO)
215 kΩ
16
11
−
+
+
−INE3
+
35 kΩ
−
OUTD
4.2 V
0.91 V
(0.77 V)
FB3
CS
15
22
VREF
UVLO
<SOFT>
VREF
1 µA
VCC
bias
18
14
VCC
CTL
<OSC>
<REF>
VREF
<CTL>
(45 pF)
5.0 V
17
RT
6
23
GND
VREF
4
MB3878
■ ABSOLUTE MAXIMUM RAGINGS
Rating
Parameter
Symbol
Conditions
VCC, VCC (O)
Unit
Min
Max
Power supply voltage
Output current
VCC
IOUT
IOUT
PD
28
60
V
mA
mA
mW
°C
Peak output current
Power dissipation
Storage temperature
Duty ≤ 5 % (t = 1 / fOSC × Duty)
Ta ≤ +25 °C
500
740*
+125
Tstg
−55
* : The package is mounted on the dual-sided epoxy board (10 cm × 10 cm).
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
Symbol
Parameter
Conditions
VCC, VCC (O)
Unit
Min
Typ
Max
Power supply voltage
VCC
IREF
7
25
V
Reference voltage output
current
−1
0
mA
VH pin output current
IVH
VINE
VINC
VOUTD
IOUTD
VCTL
IOUT
IOUT
fOSC
RT
0
0
30
VCC − 1.8
VCC
17
mA
V
−INE1 to −INE3, +INE1, +INE2
+INC1, +INC2, −INC1, −INC2
Input voltage
0
V
OUTD pin output voltage
OUTD pin output current
CTL pin input voltage
output current
0
V
0
2
mA
V
0
25
−45
−450
100
33
45
mA
mA
kHz
kΩ
Peak output current
Oscillator frequency
Timing resistor
Duty ≤ 5 % (t = 1 / fosc × Duty)
450
500
130
290
47
Soft-start capacitor
VH pin capacitor
CS
2200
0.1
100000 pF
CVH
1.0
1.0
+85
µF
µF
°C
Reference voltage output
capacitor
CREF
Ta
0.1
Operating ambient temperature
−30
+25
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.
5
MB3878
■ ELECTRICAL CHARACTERISTICS
(Ta = +25 °C, VCC = 19 V, VCC (O) = 19 V, VREF = 0 mA)
Value
Pin
No.
Parameter
Symbol
Conditions
Unit
Min
Typ
5.000
5.000
3
Max
5.045
5.055
10
Ta = +25 °C
4.995
V
V
Output voltage
VREF
6
Ta = −30 °C to +85 °C 4.945
VCC = 7 V to 25 V
Reference
voltage block
(Ref)
Input stability
Load stability
Line
6
6
mV
mV
Load
VREF = 0 mA to −1 mA
1
10
Short-circuit
output current
Ios
VTLH
VTHL
6
VREF = 1 V
−25
6.1
5.1
−15
6.4
5.4
−5
6.7
5.7
mA
V
VCC = VCC (O) ,
VCC =
18
18
Threshold voltage
VCC = VCC (O) ,
VCC =
V
Under voltage
lockout protection
circuit block
(UVLO)
Hysteresis width
Threshold voltage
VH
VTLH
VTHL
VH
18 VCC = VCC (O)
0.7
2.6
1.0
2.8
1.3
3.0
V
V
V
V
6
6
6
VREF =
VREF =
2.4
2.6
2.8
Hysteresis width
Charge current
VH = VTLH − VTHL
0.05
0.20
0.35
Soft-start block
(SOFT)
ICS
22
−1.3
−0.8
−0.5
µA
Oscillation
frequency
fOSC
20 RT = 47 kΩ
260
290
320
kHz
Triangular
waveform
oscillator circuit
block (OSC)
Frequency
temperature
stability
∆f/fdt
20 Ta = −30 °C to +85 °C
1*
%
Input offset
voltage
3,4,
8, 9
VIO
IB
FB1 = FB2 = 2 V
1
5
mV
nA
3,4,
8, 9
Input bias current
−100
−30
Common mode
input voltage
range
3,4,
8, 9
VCC −
1.8
VCM
0
V
Error amplifier
block
(Error Amp.1,
Error Amp.2)
Voltage gain
AV
5, 7 DC
100*
2.0*
dB
Frequency
bandwidth
BW
5, 7 AV = 0 dB
MHz
VFBH
VFBL
5, 7
5, 7
4.7
4.9
20
V
Output voltage
200
mV
Output source
current
ISOURCE 5, 7 FB1 = FB2 = 2 V
ISINK 5, 7 FB1 = FB2 = 2 V
−2.0
−0.6
mA
Output sink
current
150
300
µA
* : Standard design value.
(Continued)
6
MB3878
(Ta = +25 °C, VCC = 19 V, VCC (O) = 19 V, VREF = 0 mA)
Value
Pin
No.
Parameter
Symbol
Conditions
Unit
Min
Typ
Max
VTH1
16 FB3 = 2 V, Ta = +25 °C 4.167
FB3 = 2 V,
4.200
4.233
V
V
Threshold voltage
VTH2
16
4.158
4.200
4.242
Ta = −30 °C to +85 °C
Input current
Voltage gain
IINE3
AV
16 −INE3 = 0 V
−100
−30
nA
dB
15 DC
100*
Frequency
bandwidth
BW
15 AV = 0 dB
2.0*
MHz
Error amplifier
block
(Error Amp.3)
VFBH
15
15
4.7
4.9
20
V
Output voltage
VFBL
200
mV
Output source
current
ISOURCE
15 FB3 = 2 V
−2.0
300
0
−0.6
mA
µA
µA
Output sink current
ISINK
15 FB3 = 2 V
150
OUTD pin output
leak current
ILEAK
11 OUTD = 16.8 V
1
OUTD pin output
ON resistor
RON
I+INCH
11 OUTD = 1 mA
70
10
100
20
Ω
µA
µA
µA
µA
V
+INC1 = +INC2 = 12.7 V,
−INC1 = −INC2 = 12.6 V
13,
24
+INC1 = +INC2 = 12.7 V,
−INC1 = −INC2 = 12.6 V
1,
12
I−INCH
0.1
0.2
Input current
+INC1 = +INC2 = 0.1 V,
−INC1 = −INC2 = 0 V
13,
24
I+INCL
−130
−140
2.25
−65
−70
2.5
+INC1 = +INC2 = 0.1 V,
−INC1 = −INC2 = 0 V
1,
12
I−INCL
+INC1 = +INC2 = 12.7 V,
−INC1 = −INC2 = 12.6 V
2,
10
VOUTC1
VOUTC2
VOUTC3
VOUTC4
2.75
1.00
Current
detection
amplifier block
(Current Amp.1,
Current Amp.2)
+INC1 = +INC2 = 12.63 V,
−INC1 = −INC2 = 12.6 V
2,
10
0.50
0.75
2.50
0.750
V
Current detection
voltage
+INC1 = +INC2 = 0.1 V,
−INC1 = −INC2 = 0 V
2,
10
1.25
3.75
V
+INC1 = +INC2 = 0.03 V,
−INC1 = −INC2 = 0 V
2,
10
0.125
1.375
V
1,
Common mode
input voltage
range
12,
13,
24
VCM
0
Vcc
V
2,
10
+INC1 = +INC2 = 12.7 V,
−INC1 = −INC2 = 12.6 V
Voltage gain
AV
22.5
25
27.5
V/V
Frequency
bandwidth
2,
10
BW
AV = 0 dB
2.0*
MHz
* : Standard design value.
(Continued)
7
MB3878
(Continued)
(Ta = +25 °C, VCC = 19 V, VCC (O) = 19 V, VREF = 0 mA)
Value
Pin
No.
Parameter
Symbol
Conditions
Unit
Min
Typ
4.9
20
Max
VOUTCH 2, 10
4.7
V
Output voltage
VOUTCL 2, 10
200
mV
Current detection
amplifier block
(Current Amp.1,
Current Amp.2)
Output source
current
ISOURCE 2, 10 OUTC1 = OUTC2 = 2 V
−2.0
300
−0.6
mA
µA
V
Output sink
current
ISINK
VTL
2, 10 OUTC1 = OUTC2 = 2 V
150
1.4
5, 7,
Duty cycle = 0 %
1.5
PWM comparator
block
(PWM Comp.)
15
Threshold voltage
5, 7,
15
VTH
Duty cycle = 100 %
2.5
2.6
V
Output source
current
OUT = 11 V, Duty ≤ 5 %
20
ISOURCE
ISINK
−200*
200*
mA
mA
(t = 1 / fOSC × Duty)
Output sink
current
OUT = 16 V, Duty ≤ 5 %
20
(t = 1 / fOSC × Duty)
ROH
20 OUT = −45 mA
20 OUT = 45 mA
8.0
6.5
12.0
9.7
Ω
Ω
Output block
(OUT)
Output ON
resistor
ROL
OUT = 3300 pF
20
Rise time
Fall time
tr1
tf1
70*
60*
ns
ns
(equivalent to Si4435 × 1)
OUT = 3300 pF
20
(equivalent to Si4435 × 1)
VON
VOFF
ICTLH
ICTLL
14 Active mode
14 Standby mode
14 CTL = 5 V
2
0
25
0.8
200
1
V
V
CTL input voltage
Input current
Control block
(CTL)
100
0
µA
µA
14 CTL = 0 V
VCC = VCC (O)
19 = 7 V to 25 V,
VH = 0 to 30 mA
Bias voltage
block (VH)
VCC −
5.5
VCC −
VCC −
Output voltage
Standby current
VH
V
5.0
4.5
18, VCC = VCC (O) ,
19 CTL = 0 V
ICCS
ICC
0
10
µA
General
Power supply
current
18, VCC = VCC (O) ,
19 CTL = 5 V
8.0
12.0
mA
* : Standard design value
8
MB3878
■ TYPICAL CHARACTERISTICS
Power supply current vs. power supply voltage
Reference voltage vs. power supply voltage
12
10
Ta = +25 °C
CTL = 5 V
Ta = +25 °C
CTL = 5 V
10
VREF = 0 mA
8
8
6
4
2
0
6
4
2
0
0
5
10
15
20
25
0
5
10
15
20
25
Power supply voltage VCC (V)
Power supply voltage VCC (V)
Reference voltage vs. VREF load current
Reference voltage vs. ambient temperature
2.0
10
VCC = 19 V
Ta = +25 °C
VCC = 19 V
CTL = 5 V
1.5
VREF = 0 mA
CTL = 5 V
8
1.0
0.5
0.0
6
4
2
0
−0.5
−1.0
−1.5
−2.0
−40 −20
0
20
40
60
80
100
0
5
10
15
20
25
30
VREF load current IREF (mA)
Ambient temperature Ta ( °C)
Reference voltage vs. CTL pin voltage
CTL pin current vs. CTL pin voltage
1.0
0.8
0.6
0.4
0.2
0.0
10
8
Ta = +25 °C
VCC = 19 V
Ta = +25 °C
VCC = 19 V
VREF = 0 mA
6
4
2
0
0
5
10
15
20
25
0
0.5
1
1.5
2
2.5
CTL pin voltage VCTL (V)
CTL pin voltage VCTL (V)
(Continued)
9
MB3878
Triangular wave oscillator frequency vs.
Triangular wave oscillator frequency vs.
power supply voltage
timing resistor
340
1 M
100 k
10 k
Ta = +25 °C
VCC = 19 V
CTL = 5 V
Ta = +25 °C
CTL = 5 V
330
320
310
300
290
280
270
260
250
240
RT = 47 kΩ
0
5
10
15
20
25
10 k
100 k
1 M
Timing resistor RT (Ω)
Power supply voltage VCC (V)
Error amplifier threshold voltage vs.
ambient temperature (Error Amp.3)
Triangular wave oscillator frequency
5.0
4.0
340
330
320
310
300
290
280
270
260
250
240
VCC = 19 V
CTL = 5 V
VCC = 19 V
CTL = 5 V
RT = 47 kΩ
3.0
2.0
1.0
0.0
−1.0
−2.0
−3.0
−4.0
−5.0
−40 −20
0
20
40
60
80
100
−40 −20
0
20
40
60
80
100
Ambient temperature Ta ( °C)
Ambient temperature Ta ( °C)
(Continued)
10
MB3878
(Continued)
Error amplifier gain and phase vs. frequency
Ta = +25 °C
40
20
AV
180
90
VCC = 19 V
240 kΩ
5.2 V
10 kΩ
φ
1 µF
IN
2.4 kΩ
−
+
8
(4)
−
+
OUT
0
0
7
(5)
9
10 kΩ
−20
−40
−90
−180
(3)
2.5 V
Error Amp.1
(Error Amp.2)
1 k
10 k
100 k
1 M
10 M
Frequency f (Hz)
Current detection amplifier gain and phase
vs. frequency
Ta = +25 °C
φ
40
180
VCC = 19 V
20
AV
90
13
(24)
+
×25
−
OUT
0
0
10
(2)
12
(1)
12.55 V
−20
−40
−90
−180
Current Amp.1
(Current Amp.2)
12.6 V
1 k
10 k
100 k
1 M
10 M
Frequency f (Hz)
Power dissipation vs. ambient temperature
800
740
700
600
500
400
300
200
100
0
−40 −20
0
20
40
60
80
100
Ambient temperature Ta ( °C)
11
MB3878
■ FUNCTIONAL DESCRIPTION
1. DC/DC Converter Unit
(1) Reference voltage block (Ref)
The reference voltage generator uses the voltage supplied from the VCC terminal (pin 18) to generate a tem-
perature-compensated, stable voltage (5.0V Typ) used as the reference supply voltage for the IC’s internal
circuitry.
This pin can also be used to obtain a load current to a maximum of 1mA from the reference voltage VREF
terminal (pin 6).
(2) Triangular wave oscillator block (OSC)
The triangular wave oscillator builds the capacitor for frequency setting into, and generates the triangular wave
oscillator waveform by connecting the frequency setting resistor with the RT terminal (pin 17).
The triangular wave is input to the PWM comparator on the IC.
(3) Error amplifier block (Error Amp.1)
This amplifier detects the output signal from the current detector ampifier (Current amp .1), compares this to the
+INE1 terminal (pin 9), and outputs a PWM control signal to be used in controlling the charging current.
In addition, an arbitrary loop gain can be set up by connecting a feedback resistor and capacitor between the
FB1 terminal (pin 7) and -INE terminal (pin 8), providing stable phase compensation to the system.
(4) Error amplifier block (Error Amp.2)
This amplifier (Error Amp.2) detects voltage pendency of the AC adaptor and outputs a PWM control signal.
In addition, an arbitrary loop gain can be set by connecting a feedback resistor and capacitor from the FB2
terminal (pin 5) to the -INE2 terminal (pin 4) of the error amplifier, enabling stable phase compensation to the
system.
(5) Error amplifier block (Error Amp.3)
This error amplifier (Error Amp. 3) detects the output voltage from the DC/DC converter and outputs the PWM
control signal. External output voltage setting resistors can be connected to the error amplifier inverse input pin
to set the desired level of output voltage from 1 cell to 4 cells.
In addition, an arbitrary loop gain can be set by connecting a feedback resistor and capacitor from the FB3
terminal (pin 15) to the −INE3 terminal (pin 16) of the error amplifier, enabling stable phase compensation to the
system.
Connecting a soft-start capacitor to the CS terminal (pin 22) prevents surge currents when the IC is turned on.
Using an error amplifier for soft-start detection makes the soft-start time constant, independent of the output load.
(6) Current detector amplifier block (Current Amp.1)
The current detection amplifier (Current Amp.1) detects a voltage drop which occurs between both ends of the
output sense resistor (RS) due to the flow of the charge current, using the +INC1 terminal (pin 13) and
−INC1 terminal (pin 12). Then it outputs the signal amplified by 25 times to the error amplifier (Error Amp.1) at
the next stage.
12
MB3878
(7) PWM comparator block (PWM Comp.)
The PWM comparator circuit is a voltage-pulse width converter for controlling the output duty of the error
amplifiers (Error Amp. 1 to Error Amp. 3) depending on their output voltage.
The PWM comparator circuit compares the triangular wave generated by the triangular wave oscillator to the
error amplifier output voltage and turns on the external output transistor during the interval in which the triangular
wave voltage is lower than the error amplifier output voltage.
(8) Output block (OUT)
The output circuit uses a totem-pole configuration capable of driving an external P-channel MOS FET.
The output “L” level sets the output amplitude to 5 V (Typ) using the voltage generated by the bias voltage block
(VH).
This results in increasing conversion efficiency and suppressing the withstand voltage of the connected external
transistor in a wide range of input voltages.
(9) Control block (CTL)
Setting the CTL terminal (pin 14) low places the IC in the standby mode. (The supply current is 10 µA at maximum
in the standby mode.)
(10) Bias voltage block (VH)
The bias voltage circuit outputs Vcc − 5 V (Typ) as the minimum potential of the output circuit. In the standby
mode, this circuit outputs the potential equal to Vcc.
2. Protection Functions
Under voltage lockout protection circuit (UVLO)
The transient state or a momentary decrease in supply voltage or internal reference voltage (VREF), which
occurs when the power supply is turned on, may cause malfunctions in the control IC, resulting in breakdown
or degradation of the system. To prevent such malfunction, the under voltage lockout protection circuit detects
a supply voltage or internal reference voltage drop and fixes the OUT terminal (pin 20) to the “H” level. The
system restores voltage supply when the supply voltage or internal reference voltage reaches the threshold
voltage of the under voltage lockout protection circuit.
3. Soft-start Function
Soft-start block (SOFT)
Connecting a capacitor to the CS terminal (pin 22) prevents surge currents when the IC is turned on. Using an
error amplifier for soft-start detection makes the soft-start time constant, independent of the output load of the
DC/DC converter.
13
MB3878
■ SETTING THE CHARGING VOLTAGE
The charging voltage (DC/DC output voltage) can be set by connecting external voltage setting resistors (R3,
R4) to the -INE3 terminal. Be sure to select a resistor value that allows you to ignore the on resistor (70 Ω, 1mA)
of the internal FET connected to the OUTD terminal (pin 11).
Battery charging voltage: VO
VO (V) = (R3 + R4) / R4 × 4.2 (V)
VO
B
R3
R4
< Error Amp.3 >
−INE3
16
11
−
+
+
4.2 V
OUTD
22
CS
■ METHOD OF SETTING THE CHARGING CURRENT
The charge current (output control current) value can be set with the voltage at the +INE1 terminal (pin 9).
If a current exceeding the set value attempts to flow, the charge voltage drops according to the set current value.
Battery charge current setting voltage : +INE1
+INE1 (V) = 25 × I1 (A) × RS (Ω)
■ METHOD OF SETTING THE SOFT-START TIME
Upon activation, the IC starts charging the capacitor (Cs) connected to the CS terminal (pin 22).
The error amplifier causes soft-start operation to be performed with the output voltage in proportion to the CS
terminal voltage regardless of the load current of the DC/DC converter.
Soft-start time: ts (Time taken for the output voltage to reach 100 %)
ts (s) =: 4.2 × CS (µF)
■ METHOD OF SETTING THE TRIANGULAR WAVE OSCILLATOR FREQUENCY
The trianguar wave oscillator frequency can be set by the timing resistor (RT)connected the RTterminal (pin 17).
Triangular wave oscillator frequency: fOSC
fOSC (kHz) =: 13630 / RT (kΩ)
14
MB3878
■ AC ADAPTOR VOLTAGE DETECTION
With an external resistor connected to the +INE2 terminal(pin 3), the IC enters the dynamically-controlled
charging mode to reduce the charge current to keep AC adaptor power constant when the partial potential point
A of the AC adaptor voltage (Vcc) becomes lower than the voltage at the -INE2 terminal.
AC adaptor detected voltage setting: Vth
Vth (V) = (R1 + R2) / R2 × −INE2
−INE2 setting voltage range : 1.176 V to 4.2 V (equivalent to 7 V to 25 V for Vcc)
<Error Amp.2>
−INE2
4
3
−
+
A
VCC
+INE2
R1
R2
■ OPERATION TIMING DIAGRAM
2.5 V
1.5 V
Error Amp.1 FB1
Error Amp.3 FB3
Error Amp.2 FB2
OUT
AC adaptor dynamically-
controlled charging
Constant current control
Constant
voltage control
AC adaptor dynamically-
controlled charging
15
MB3878
■ PROCESSING WITHOUT USE OF THE CS PIN
If the soft-start function is not used, the CS terminal (pin 22) should be left open.
Open
22
CS
When no soft-start time is specified.
■ NOTE ON AN EXTERNAL REVERSE-CURRENT PREVENTIVE DIODE
• Insert a reverse-current preventive diode at one of the three locations marked * to prevent reverse current from
the battery.
• When selecting the reverse current prevention diode, be sure to consider the reverse voltage (VR) and reverse
current (IR) of the diode.
VIN
VCC(O)
21
∗
A
B
OUT
20
19
I1
∗
BATT
RS
∗
VH
Battery
16
MB3878
■ APPLICATION EXAMPLE 1
17
MB3878
■ PARTS LIST (for APPLICATION EXAMPLE 1)
COMPONENT
ITEM
SPECIFICATION
VENDOR
PARTS No.
VISHAY
SILICONIX
VISHAY
Q1
Q2
FET
FET
Si4435DY
2N7002
Si4435DY
2N7002
SILICONIX
D1
L1
Diode
Coil
MBRS130LT3
MOTOROLA
SUMIDA
MBRS130LT3
12 µH
4.0 A, 38 mΩ
CDRH124-12 µH
C1
C2, C3
CS
C5
C6
C7
C8
C9
C10
OS Condenser
OS Condenser
22 µF
100 µF
2200 pF
0.1 µF
25 V (10 %)
25 V (10 %)
10 %
Ceramics Condenser
Ceramics Condenser
Ceramics Condenser
Ceramics Condenser
Ceramics Condenser
Ceramics Condenser
Ceramics Condenser
16 V
1500 pF
0.1 µF
10 %
25 V
10 %
16 V
10000 pF
0.1 µF
5600 pF
10 %
RS
RT
R3
R4
R5
R6
R7
R8
R9
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
0.033 Ω
47 kΩ
1.0 %
1.0 %
1.0 %
0.5 %
0.5 %
0.5 %
1.0 %
1.0 %
1.0 %
0.5 %
0.5 %
0.5 %
5 %
330 kΩ
82 kΩ
330 kΩ
68 kΩ
22 kΩ
100 kΩ
10 kΩ
30 kΩ
1.3 kΩ
110 Ω
200 kΩ
100 kΩ
200 kΩ
R10 to R13
R14
R15
R16
R17
R18
0.5 %
0.5 %
Note VISHAY SILICONIX : VISHAY Intertechnology, Inc.
MOTOROLA : Motorola Japan Ltd.
SUMIDA : SUMIDA ELECTRIC CO., Ltd.
18
MB3878
■ REFERENCE DATA
Conversion efficiency vs. charge current
(Fixed voltage mode)
Conversion efficiency vs. charge voltage
(Fixed current mode)
100
98
96
94
92
90
88
86
84
82
80
100
98
96
94
92
90
88
86
84
82
80
VIN = 19 V
VIN = 19 V
BATT : Electronic load,
(Product of KIKUSUI PLZ-150W)
BATT charge voltage = 12.6 V fOSC = 277.9 kHz
η (%) = (VBATT × IBATT) / (VIN × IIN) × 100
10 m
100 m
1
10
0
2
4
6
8
10
12
14
16
BATT charge current IBATT (A)
BATT charge voltage VBATT (V)
BATT voltage vs. BATT charge current
18
16
14
12
10
8
VIN = 19 V
BATT : Electronic load,
(Product of KIKUSUI PLZ-150W)
DCC MODE
Dead Battery MODE
6
4
2
DCC : Dynamically Controlled Charging
5
0
0
1
2
3
4
BATT charge current IBATT (A)
DC/DC converter switching waveforms
Soft-start operating waveforms
VIN = 19 V
VIN = 19 V
fOSC = 277.9 kHz
Load : BATT = 1 A
Load : BATT = 20 Ω
−INE2 = 0 V
OUTH (V)
20
BATT (V)
20
5 V
5 V
15
10
5
15
10
CTL (V)
20
5
0
0
15
10
5
FB3 (V)
4
2
0
0
2 V
2
1 µs
5 V
40
20 ms
0
4
6
8
10
0
80
120
160
200
t (µs)
t (ms)
19
MB3878
■ APPLICATION EXAMPLE 2
20
MB3878
■ PARTS LIST (for APPLICATION EXAMPLE 2)
COMPONENT
ITEM
SPECIFICATION
VENDOR
PARTS No.
Q1
Q2
FET
FET
Si4435DY
2N7002
VISHAY SILICONIX
VISHAY SILICONIX
Si4435DY
2N7002
D1
A
Diode
MBRS130LT3
MB47358
MOTOROLA
Our Company
MBRS130LT3
MB47358
Dual Op-amp
4.0 A,
12 µH
L1
Coil
SUMIDA
CDRH124-12 µH
38 mΩ
C1
C2, C3
CS
C5
C6
C7
C8
C9
C10
OS Condenser
OS Condenser
Ceramics Condenser 2200 pF
Ceramics Condenser
Ceramics Condenser 1500 pF
Ceramics Condenser 0.1 µF
Ceramics Condenser 10000 pF
Ceramics Condenser 0.1 µF
Ceramics Condenser 5600 pF
22 µF
25 V (10 %)
25 V (10 %)
10 %
100 µF
0.1 µF
16 V
10 %
25 V
10 %
16 V
10 %
RS1, RS2
RT
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
0.033 Ω
47 kΩ
1.0 %
1.0 %
1.0 %
1.0 %
1.0 %
1.0 %
0.5 %
0.5 %
0.5 %
0.5 %
0.5 %
5 %
1.0 %
0.5 %
1.0 %
0.5 %
1.0 %
R3
R7
R8
R9
330 kΩ
22 kΩ
100 kΩ
10 kΩ
R10
R11
R12, R13
R14
36 kΩ
27 kΩ
30 kΩ
1.3 kΩ
110 Ω
R15
R16
R17
R18
200 kΩ
100 kΩ
200 kΩ
100 kΩ
100 kΩ
100 kΩ
R19, R20
R21, R22
R23
Note VISHAY SILICONIX : VISHAY Intertechnology, Inc.
MOTOROLA : Motorola Japan Ltd.
SUMIDA : SUMIDA ELECTRIC CO., Ltd.
21
MB3878
■ USAGE PRECAUTIONS
• Printed circuit board ground lines should be set up with consideration for common impedance.
• Take appropriate static electricity measures.
• Containers for semiconductor materials should have anti-static protection or be made of conductive material.
• After mounting, printed circuit boards should be stored and shipped in conductive bags or containers.
• Work platforms, tools, and instruments should be properly grounded.
• Working personnel should be grounded with resistance of 250 kΩ to 1 MΩ between body and ground.
• Do not apply negative voltages.
The use of negative voltages below –0.3 V may create parasitic transistors on LSI lines, which can cause
abnormal operation
■ ORDERING INFORMATION
Part number
MB3878PFV
Package
Remarks
24-pin plastic SSOP
(FPT-24P-M03)
22
MB3878
■ PACKAGE DIMENSION
24-pin plastic SSOP
(FPT-24P-M03)
Note1: Pins width and pins thickness include plating thickness.
Note2: * This dimension does not include resin protrusion.
0.17±0.03
(.007±.001)
*
7.75±0.10(.305±.004)
24
13
5.60±0.10 7.60±0.20
(.220±.004) (.299±.008)
INDEX
Details of "A" part
1.25 +0.20
–0.10
–.004
(Mounting height)
.049 +.008
0.25(.010)
0~8°
"A"
1
12
0.24 +0.08
.009 +.003
–0.07
0.65(.026)
M
0.13(.005)
–.003
0.50±0.20
0.10±0.10
(.020±.008)
(.004±.004)
(Stand off)
0.60±0.15
(.024±.006)
0.10(.004)
C
2001 FUJITSU LIMITED F24018S-c-3-4
Dimensions in mm (inches)
23
MB3878
FUJITSU LIMITED
All Rights Reserved.
The contents of this document are subject to change without notice.
Customers are advised to consult with FUJITSU sales
representatives before ordering.
The information and circuit diagrams in this document are
presented as examples of semiconductor device applications, and
are not intended to be incorporated in devices for actual use. Also,
FUJITSU is unable to assume responsibility for infringement of
any patent rights or other rights of third parties arising from the use
of this information or circuit diagrams.
The products described in this document are designed, developed
and manufactured as contemplated for general use, including
without limitation, ordinary industrial use, general office use,
personal use, and household use, but are not designed, developed
and manufactured as contemplated (1) for use accompanying fatal
risks or dangers that, unless extremely high safety is secured, could
have a serious effect to the public, and could lead directly to death,
personal injury, severe physical damage or other loss (i.e., nuclear
reaction control in nuclear facility, aircraft flight control, air traffic
control, mass transport control, medical life support system, missile
launch control in weapon system), or (2) for use requiring
extremely high reliability (i.e., submersible repeater and artificial
satellite).
Please note that Fujitsu will not be liable against you and/or any
third party for any claims or damages arising in connection with
above-mentioned uses of the products.
Any semiconductor devices have an inherent chance of failure. You
must protect against injury, damage or loss from such failures by
incorporating safety design measures into your facility and
equipment such as redundancy, fire protection, and prevention of
over-current levels and other abnormal operating conditions.
If any products described in this document represent goods or
technologies subject to certain restrictions on export under the
Foreign Exchange and Foreign Trade Law of Japan, the prior
authorization by Japanese government will be required for export
of those products from Japan.
F0209
FUJITSU LIMITED Printed in Japan
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