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MITSUMI
Secondary Control for Energy-Saving AC Adaptor MM1548
Secondary Control for Energy-Saving AC Adaptor
Monolithic IC MM1548
Outline
This IC is secondary control on AC adaptors that have energy-saving mode. The energy-saving mode function operates when charging is completed or when the set is unplugged, thus greatly reducing AC adaptor power consumption. When a set is connected, normal mode automatically starts and charging starts. Compared to the conventional MM1529, this IC is smaller and has fewer external components.
Features
1. Automatic switching between energy-saving mode and normal mode 2. Current consumption (energy-saving mode) 60A 3. Current consumption (normal mode) 1.5mA 4. Uses one photocoupler to control oscillator primary side. 5. One photocoupler is used to control rated voltage and rated current and switching between energy-saving and normal modes.
Package
SOT-26
Pin Assignment
1 1 2 3 SOT-26 6 5 4 2 3 OUT CNT VCC 4 5 6 PO1 GND CS
MITSUMI
Secondary Control for Energy-Saving AC Adaptor MM1548
Block Diagram
Load detection resistor RLS
PC1 Primary-side switching control transformer secondary side RL1
RLB
PO1
VCC
CNT
OUT
4
Photocoupler-turn-off
3
2
1
COUT
Voltage buffer
Input/output difference control (VCC-OUT=200mV)
Load detection(current) (115mV 200mV) 1.25V Reference voltage VCC=4.6V
ROS1
VCC
Load detection(voltage) (VCC=3.5V)
5k Over voltage detection (7V)
Constant voltage control (VCC=5.1V) ROS2 Constant current control (CS=114.4mV)
(CS=34mV) Reference voltage decrease (drop)
5
GND
6
RCS Constant current detection resistor
CS
MITSUMI
Secondary Control for Energy-Saving AC Adaptor MM1548
Pin Description
Pin No. 1 Pin Name OUT Output (+) pin. Connect Registor for load detection between VCC pin, and connect collector of PNP power transistor.
1
VCC
Function
Internal equivalent circuit
2
CNT
PNP power transistor control pin. Connect base of PNP power transistor.
2
3
VCC
(+) power supply pin. This pin doubles load detection pin. Connect load detection resistor between OUT pin, and connect emitter of PNP power transistor.
1.25V
3
4
PO1
Photo diode drive pin of photocoupler for constant-current and constantvoltage control. Connect to cathode of diode.
4
5
GND
Ground pin of this IC.
6
CS
Overcurrent detection pin.
VCC
This pin doubles as output- pin. Connect Resistor for overcurrent detection between GND pin.
6
MITSUMI
Secondary Control for Energy-Saving AC Adaptor MM1548
Absolute Maximum Ratings
Item Storage temperature Operating temperature Supply voltage Allowable loss
(Ta=25C) Symbol TSTG TOPR VCC max. Pd Ratings -40~+125 -30~+85 -0.3~+18 150 (alone) Unit C C V mW
Recommended Operating Conditions
Item Operating temperature Supply voltage Symbol TOPR VOP Ratings -30~+85 +2.5~+12 Unit C V
Electrical Characteristics
(unless otherwise specified, Ta=+25C, Vcc=4.9V) Typ. Max. Unit. 60 110 A 1.5 3.0 mA 5.10 25 17 5.21 150 V nA mA
Item Symbol Test Conditions Min. Current consumption1(energy saving mode) ICC1 VCC=4.4V, VOUT=4.4V, VCS=0V Current consumption2(normal mode) ICC2 VCC=5.3V, VOUT=5.0V, VCS=0V Voltage control section Output inversion voltage VO IIN=5mA, VOUT=VCC-0.3V, VCS=0V 4.99 OUT input sink current IOUT VCC=4.9V, VOUT=4.9V, VCS=0V PO1 output sink current 1 IPO1 VCC=5.3V, VOUT=5.0V, VCS=0V VPO1=0.5V 5 Constant current control Output inversion voltage 1 VCC=4.9V, RCS1=1k, VOUT=4.6V, RCS2=40k, IIN=5mA 111.2 VCS1 (Constant current control) Output inversion voltage 2 VCC=2.0V, RCS1=1k, VOUT=0V, RCS2=40k, IIN=5mA 22 VCS2 (Constant current control drop) CS input source current ICS VCC=4.9V, VOUT=4.6V, VCS=0.1V Power supply voltage rejection ratio PSRR2 VCC=3.7V 4.4V, VCS=VCS1-10mV, RL1=5k 60 PO1 output sink current 2 IPO2 VCC=4.9V, VOUT=4.6V, VCS=0.2V, VPO1=0.5V 5 Input-output difference control Input-output difference control voltage VLS VCC=5.1V, RLS=4.7k, RLB=100, RO=5k 140 CNT output sink current ICNT VCC=5.1V, VOUT=4.8V, VCS=0V, VCNT=0.8V 5 Load detection Load detection voltage VLSP1 VCC=4.9V, RL1=47k, VOUT=4.9V L, VCS=0V 170 Energy saving detection voltage VLSP2 VCC=4.9V, RL1=47k, VOUT=L 4.9V, VCS=0V 85 (load detection release voltage) 3.5V undervoltage detection VOL1 VCC=H L, RL1=10k, VOUT=VCC, VCS=0V 3.4 3.5V undervoltage detection hysteresis VOL1H VCC=L H, RL1=10k, VOUT=VCC, VCS=0V 4.6V undervoltage detection VOL2 VCC=H L, RL1=47k, VOUT=VCC, VCS=0V 4.47 PO1 output sink current 3 IPO3 VCC=4.9V, VOUT=4.6V, VCS=0V, VPO2=1.0V 100 VCC=4.9V, VOUT=4.9V, VCS=0V, VPO2=4.6V 1.0 PO1 output source current IPO4 Constant current mode selection 2pin(CNT pin) disable voltage VCNTO VCC=H L, VCNT=0.8V, VOUT=VCC-0.3V, VCS=0V, ICNT < 1mA Constant current mode selection threshold VCSS VCC=4.9V, RCS1=1k, VOUT=4.6V, RCS2=20k, IIN=5mA, VCS < VCS min. (between VCC and OUT)
114.4 117.6 mV 34 5 70 17 200 30 200 115 3.5 350 4.60 200 5.0 2.4 0.6 100 mV nA dB mA mV mA mV mV V mV V A mA V V
260
230 145 3.6 4.73 400
MITSUMI
Secondary Control for Energy-Saving AC Adaptor MM1548
Measuring Circuit 1
ICC1, ICC2, IOUT, ICS, IPO1, IPO2, IPO3, IPO4, ICNT
I PO1
A
4
PO1
VCC
3
A
I CC
5 GND
I CS A VCS
CNT 2
A
I CNT
VPO1
6
CS
OUT 1
A
I CNT VOUT VCNT VCC
VCC ICC1 ICC2 IOUT ICS IPO1 IPO2 IPO3 IPO4 ICNT 4.4V 5.3V 4.9V 4.9V 5.3V 4.9V 4.9V 4.9V 5.1V
VOUT 4.4V 5.0V 4.9V 4.9V 5.0V 4.6V 4.6V 4.9V 4.8V
VCS 0.0V 0.0V 0.0V 0.1V 0.0V 0.2V 0.0V 0.0V 0.0V
VPO1 OPEN OPEN OPEN OPEN 0.5V 0.5V 1.0V 4.6V OPEN
VCNT OPEN OPEN OPEN OPEN OPEN OPEN OPEN OPEN 0.8V
Measuring Circuit 2
VLSP1, VLSP2, VOL1, VOL2
RL1
RL3
4
PO1
VCC
3
5 GND
RL2
CNT 2
V
6
CS
OUT 1
V
V OUT VCC
VCC VLSP1 VLSP1 VOL1 VOL2 4.9V 4.9V 3.7 4.8 3.3V 4.4V
VOUT 4.9 4.6 4.6V 4.9V VCC VCC
VCS 0V 0V 0V 0V
VPO1
VCNT
RL1=47k RL3=10k RL1=47k RL3=10k RL1=10k RL2=47k OPEN OPEN
MITSUMI
Secondary Control for Energy-Saving AC Adaptor MM1548
Measuring Circuit 3
VLS
4 PO1 VCC 3
RLB 2SB1424 VCC
RLS
5 GND
CNT 2
100 4.7k
V
6
CS
OUT 1
COUT RO 5k 100F
Measuring Circuit 4
PSRR2
4 V
10k 100 RL1 5k
PO1
VCC
3
V CC 3.7V 4.4V
5 GND
CNT 2
6
VCS
CS
OUT 1
VOUT VCC-0.3V
Measuring Circuit 5
VO
I in 5mA
4
PO1
VCC
3
V
5 GND
CNT 2
6
CS
OUT 1
VOUT
Measuring Circuit 6
VCS1, VCS2
I in 5mA
4
PO1
VCC
3
VCC
RCS2
5 GND
CNT 2
V 6
RCS1
CS
OUT 1
VOUT
MITSUMI
Secondary Control for Energy-Saving AC Adaptor MM1548
Operation
Voltage between VCC and OUT(200mV)
RLS 470 Supply transistor VCC CNT RLB 100
Load current
Output (+)
OUT
200mV
Input/output difference control
PC1
200mV
Load current detection
Voltage drop detection (V=4.6V) Voltage drop detection (VCC=3.5V) Constant voltage control (VCC=5.1V)
ROS1 REF ROS2
Overvoltage detection
(VCC, OUT=7V)
115mV Energy saving current detection Energy saving mode Normal mode
Energy saving mode control
(3.5V :ON, 5.1V :OFF) Photocoupler-turn-off(4.6V ) PO1 drive(Load 5k)
Constant current control (CS=114.4mV) (Io=520mA)
PO1 drive
Photocoupler PC1 control
PO1
GND
RCS 0.22
CS (-)
1. Operation of Blocks 1.1 Input/output difference control In the normal mode that a load current is detected and the system supplies the load current through the Supply Transistor (PNP type), MM1548 controls CNT current flowing into the base of Supply Transistor to keep the differential voltage between VCC and OUT (Vce of Supply Transistor) at 200mV. 1.2 Load current detection and Energy saving current detection When load current increases in energy saving mode and the differential voltage between VCC and OUT exceeds VLSP1 (200mV), MM1548 changes to the normal mode, PO1 switches from open to low mode, and the photocoupler PC1turns on. As a result, the system switches primary-side switching operation to normal mode from disabled. The switching voltage has following hysteresis if load current is increasing ( VLSP1) or decreasing ( VLSP2). ( hysteresis: VLSP1 = 200mV < > VLSP2 = 115mV) When the differential voltage between VCC and OUT falls to VLSP2 (115mV), MM1548 changes to the energy saving mode, and the photocoupler-turn-off circuit switches compulsory photocoupler current to zero under the condition that load current is decreasing in normal mode and Vcc = 4.6V or more. 1.3 Voltage drop detection When VCC voltage falls to 4.6V in the energy saving mode, MM1548 stops the photocoupler-turn-off circuit operation to save consumption current of MM1548. When VCC voltage falls to 3.5V in the energy saving mode, MM1548 changes to the normal mode. As a result, Out voltage (output of secondary side) swings intermittent between 4.9V and 3.5V. 1.4 Constant current control When load current is increasing in the normal mode, and the differential voltage between CS and GND exceeds VCS1(114.4mV typ.), PO1 switches from open to low mode, and the photocoupler PC1 turns on. As a result, MM1548 changes to the CC(constant current) mode, and the load current is controlled that CS voltage keeps VCS1. 1.5 Constant voltage control When MM1548 is in normal mode and isn't in constant current mode, it is in CV(constant voltage) mode, and PO1 current is controlled that VCC voltage keeps 5.1V (equal to internal 1.25V: REF voltage).
Load
MITSUMI
Secondary Control for Energy-Saving AC Adaptor MM1548
1.6 Overvoltage detection When VCC voltage or OUT voltage exceeds 7V (overvoltage), overvoltage detection circuit turn on. As a result, PO1 sink current is controlled to turn on the photocoupler PC1, and system is protected from overvoltage. This circuit also detects negative voltage applied CS pin, and when it is detected, PO1 current is turned off for overvoltage protection. 2. Design principles for each mode AC adaptor output is controlled by following 4 mode under usage with MM1548. Switching of each control mode is explained as follow.
Vo(5.1V typ.)- VLS(0.2V typ.) Output voltage (between OUT and CS) [V]
Energy saving mode (PO1:Open)
CV MODE (PO1:Control) VCS(115mV typ.)
Energy saving current detection (load detection release ) Load current detection CC MODE (PO1:Control)
CC MODE Drop curve (PO1:Control) Load current [A] (115mV/RLS) (200mV/RLS) 34mV/RCS 114.4mV/RCS
2.1 for Output voltage In MM1548 series, the output voltage can't be adjusted by external resistor, because referential voltage terminal (REF pin) for adjustment is build in the chip. Instead of voltage adjustment, you can chose output voltage by select the rank of MM1548 series. Output voltage is lower 0.2V (equal to in-out differential control voltage) than 5.1V(equal to the value set by ROS1 and ROS2). [Formula] Output voltage = Vo - VLS = {1+(ROS1/ ROS2)} 1.25 - VLS = {1+(2460k/800k)} 1.25 - 0.2 = 4.9V
(Vo = 5.1V) ( VLS = 0.2V)
MITSUMI
Secondary Control for Energy-Saving AC Adaptor MM1548
2.2 for Constant current detection (RCS adjust method) Constant current value is set by RCS value as load detection resistor. On the design, constant current operation changes when [load current] > 520[mA] in the case of 0.22 use. [Formula] [Constant current control] = VCS1 / RCS [Drop curve] = VCS2 / RCS
(VCS1 = 114.4mV) (VCS2 = 34mV)
RCS(constant current detection resistor) - constant current control value
1200 1100 constant current control value [mA]
I= (VCS1) / RCS
1000 900 800 700 600 500 400 300 200 0.1 RCS(constant current detection resistor) [] min. typ.
0.22
max.
1.0
2.3 Description of load detection and energy saving detection (RLS adjust method) Load detection current and energy saving detection current is set by RLS as load detection resistor. On the design, each current changes when [current flows through RLS] > 240A, in the case of 470 use. [Formula] [Load detection current] = ( VLSP1 / RLS) ( VLSP1 = 200mV) [Energy saving detection current] = ( VLSP2 / RLS) ( VLSP2 = 115mV)
RLS (Load detection resistor) - Energy saving detection current
1200 1100 Energy saving detection current [A] 1000 900 800 700 600 500 400 300 200 100 0 0.1 min. typ.
I= (
VLSP2) / RLS
470
max.
1 RLS (Load detection resistor)
10 [k]
MITSUMI
Secondary Control for Energy-Saving AC Adaptor MM1548
Timing Chart
Constant voltage control
Normal mode [Io>115mV / RLS]
VCC 2 1 4.9V VCC, OUT PIN (secondary side output)
0V 5.1V 5.1V 4.9V 3.5V 0V
Energy saving mode [Io<115mV / RLS]
VCC
OUT
OUT
3 PO1 current (load det. + constant voltage control output)
0mA ON
0mA ON
4 Primary side switching
OFF OFF
Normal mode
Energy saving mode
Energy saving mode Normal mode
Normal mode
Constant current control
Normal control [VCC>2.0V]
2 1 VCC, OUT PIN (secondary side output) 2V
0V 200mV
Drop control [VCC<2.0V]
VCC OUT
2V 0V over 0.6V
OUT 3 PO1 current (load det. + constant voltage control output)
0mA ON 0mA ON
4 Primary side switching
OFF
OFF
114.4mV 5 CS terminal (constant current control input) 0mV
34mV 0mV 1 RLS 2 output
AC input
4
+
Rectifying circuit
VCC CNT OUT MM1548 PO1 GND CS RCS
Delay circuit
Smoothing circuit
Switching interruption control
-
5
Switching circuit
3
Signal detection circuit
Photocoupler
MITSUMI
Secondary Control for Energy-Saving AC Adaptor MM1548
Timing Chart
Load / Energy-saving detection
Load current decrease
Load current decrease 5 Load current
Load detection current (200mV/RLS) Energy saving current (115mV/RLS) 0mA
VCC
1 VCC PIN 2 OUT PIN
5.1V
4.9V 115mV 200mV
OUT
0V
3 PO1 PIN
Open
Low(Load 5k)
4 CNT PIN
Open
Control
Load current increase
Load current increase 5 Load current
Load detection current (200mV/RLS) Energy saving current (115mV/RLS) 0mA
VCC
1 VCC PIN 2 OUT PIN
5.1V
4.9V 200mV
OUT
0V
3 PO1 PIN
Open
Low(Load 5k)
4 CNT PIN
Open
Control
1
2 RLS 5
AC input
Output +
4 Rectifying circuit Delay circuit Smoothing circuit
VCC CNT OUT
MM1548
PO1 GND CS
RCS Switching interruption control Switching circuit 3
-
signal detection circuit
Photocoupler
MITSUMI
Secondary Control for Energy-Saving AC Adaptor MM1548
Application Circuit
INPUT
10 R20 4.7 C2 L1 4.7
6.8
1M R1 R2
T1
L2
470 R15
OUTPUT
+
C9
C7 470
AC100V
D1
C8 220
C12
Q5 220
2.2M
R3
D4
R18
270k R4
1.5M
R5
DC4.9V 520mA
D3 Q1 C13 0.0056
VCC CNT OUT
470 R7 C6 0.22 3.3M Q2 R8 100k Q3 470 R10 0.1 C4 C5 R9 4700p C3 D2 1000p
PO1
100
MM 1548
GND CS 470 0.22 C10 R17 0.22 R16
-
Q4
R11
R13
10k
R14 100k R12 10k Q6
10k
R19 10
PH1
C11 2200p

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