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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) 60? 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 mitsumi pin assignment 1 6 2 5 3 4 sot-26 1 out 4 po1 2 cnt 5 gnd 3 v cc 6 cs
mitsumi secondary control for energy-saving ac adaptor MM1548 mitsumi block diagram gnd 5 cs 6 po1 4 v cc 3 cnt 2 out 1 c out ros1 ros2 rcs constant current detection resistor (cs=34mv) reference voltage decrease (drop) constant current control (cs=114.4mv) constant voltage control (v cc =5.1v) load detection(voltage) (v cc =3.5v) over voltage detection (7v) 5k load detection(current) (115mv 200mv) input/output difference control (vcc-out=200mv) voltage buffer photocoupler-turn-off primary-side switching control rls load detection resistor rlb v cc 1.25v reference voltage pc1 rl1 transformer secondary side v cc =4.6v
mitsumi secondary control for energy-saving ac adaptor MM1548 pin description pin no. pin name function internal equivalent circuit 1 out output (+) pin. connect registor for load detection between v cc pin, and connect collector of pnp power transistor. v cc 1 2 1.25v 3 4 6 v cc 2 cnt pnp power transistor control pin. connect base of pnp power transistor. 4 po1 photo diode drive pin of photocoupler for constant-current and constant- voltage control. connect to cathode of diode. 5 gnd ground pin of this ic. 6 cs overcurrent detection pin. this pin doubles as output- pin. connect resistor for overcurrent detection between gnd pin. 3 v cc (+) power supply pin. this pin doubles load detection pin. connect load detection resistor between out pin, and connect emitter of pnp power transistor.
mitsumi secondary control for energy-saving ac adaptor MM1548 absolute maximum ratings (ta=25?) recommended operating conditions electrical characteristics (unless otherwise specified, ta=+25c, vcc=4.9v) item symbol ratings unit storage temperature t stg ?0~+125 c operating temperature t opr ?0~+85 c supply voltage v cc max. ?.3~+18 v allowable loss pd 150 (alone) mw item symbol ratings unit operating temperature t opr ?0~+85 c supply voltage v op +2.5~+12 v item symbol test conditions min. typ. max. unit. current consumption1(energy saving mode) i cc1 v cc =4.4v, v out =4.4v, v cs =0v 60 110 ? current consumption2(normal mode) i cc2 v cc =5.3v, v out =5.0v, v cs =0v 1.5 3.0 ma voltage control section output inversion voltage v o i in =5ma, v out =v cc ?.3v, v cs =0v 4.99 5.10 5.21 v out input sink current i out v cc =4.9v, v out =4.9v, v cs =0v 25 150 na po1 output sink current 1 i po1 v cc =5.3v, v out =5.0v, v cs =0v v po1 =0.5v 5 17 ma constant current control output inversion voltage 1 v cs1 v cc =4.9v, r cs1 =1k ? , v out =4.6v, r cs2 =40k ? , i in =5ma 111.2 114.4 117.6 mv (constant current control) output inversion voltage 2 v cs2 v cc =2.0v, r cs1 =1k ? , v out =0v, r cs2 =40k ? , i in =5ma 22 34 mv (constant current control drop) cs input source current i cs v cc =4.9v, v out =4.6v, v cs =0.1v 5 100 na power supply voltage rejection ratio psrr2 v cc =3.7v 4.4v, v cs =v cs1 ?0mv, r l1 =5k ? 60 70 db po1 output sink current 2 i po2 v cc =4.9v, v out =4.6v, v cs =0.2v, v po1 =0.5v 5 17 ma input-output difference control input-output difference control voltage v ls v cc =5.1v, r ls =4.7k ? , r lb =100 ? , r o =5k ? 140 200 260 mv cnt output sink current i cnt v cc =5.1v, v out =4.8v, v cs =0v, v cnt =0.8v 5 30 ma load detection load detection voltage v lsp1 v cc =4.9v, r l1 =47k ? , v out =4.9v l, v cs =0v 170 200 230 mv energy saving detection voltage v lsp2 v cc =4.9v, r l1 =47k ? , v out =l 4.9v, v cs =0v 85 115 145 mv (load detection release voltage) 3.5v undervoltage detection v ol1 v cc =h l, r l1 =10k ? , v out =v cc , v cs =0v 3.4 3.5 3.6 v 3.5v undervoltage detection hysteresis v ol1h v cc =l h, r l1 =10k ? , v out =v cc , v cs =0v 350 mv 4.6v undervoltage detection v ol2 v cc =h l, r l1 =47k ? , v out =v cc , v cs =0v 4.47 4.60 4.73 v po1 output sink current 3 i po3 v cc =4.9v, v out =4.6v, v cs =0v, v po2 =1.0v 100 200 400 ? po1 output source current i po4 v cc =4.9v, v out =4.9v, v cs =0v, v po2 =4.6v 1.0 5.0 ma constant current mode selection 2pin(cnt pin) disable voltage v cnto v cc =h l, v cnt =0.8v, v out =v cc ?.3v, v cs =0v, i cnt < 1ma 2.4 v constant current mode selection threshold v css v cc =4.9v, r cs1 =1k ? , v out =4.6v, r cs2 =20k ? , i in =5ma, v cs < v cs min. 0.6 v (between v cc and out)
mitsumi secondary control for energy-saving ac adaptor MM1548 measuring circuit 1 i cc1 , i cc2 , i out , i cs , i po1 , i po2 , i po3 , i po4 , i cnt v lsp1 , v lsp2 , v ol1 , v ol2 measuring circuit 2 4 po1 v cc gnd cnt cs out 3 5 2 6 1 a v cc v po1 a a v cnt v out i cnt i cnt i cc a i po1 v cs a i cs 4 po1 v cc gnd cnt cs out 3 5 2 6 1 v v v cc v r l 3 r l 1 r l 2 out v cc v out v cs v po1 v cnt i cc1 4.4v 4.4v 0.0v open open i cc2 5.3v 5.0v 0.0v open open i out 4.9v 4.9v 0.0v open open i cs 4.9v 4.9v 0.1v open open i po1 5.3v 5.0v 0.0v 0.5v open i po2 4.9v 4.6v 0.2v 0.5v open i po3 4.9v 4.6v 0.0v 1.0v open i po4 4.9v 4.9v 0.0v 4.6v open i cnt 5.1v 4.8v 0.0v open 0.8v v cc v out v cs v po1 v cnt v lsp1 4.9v 4.9 4.6v 0v r l 1=47k ? r l 3=10k ? v lsp1 4.9v 4.6 4.9v 0v r l 1=47k ? r l 3=10k ? v ol1 3.7 3.3v v cc 0v r l 1=10k ? open v ol2 4.8 4.4v v cc 0v r l 2=47k ? open
mitsumi secondary control for energy-saving ac adaptor MM1548 4 po1 v cc gnd cnt cs out 3 5 2 6 1 v cc c 100 f ro 5k ? r l s 4.7k 100 ? out v 2sb1424 r l b r l 1 5k ? 100 ? 10k ? 4 po1 v cc gnd cnt cs out 3 5 2 6 1 v cs v v 3.7v 4.4v cc v out v cc 0.3v 4 po1 v cc gnd cnt cs out 3 5 2 6 1 v out i in 5ma v 4 po1 v cc gnd cnt cs out 3 5 2 6 1 v out i in 5ma v cc rcs2 rcs1 v v ls psrr2 v o v cs1 , v cs2 measuring circuit 3 measuring circuit 4 measuring circuit 5 measuring circuit 6
mitsumi secondary control for energy-saving ac adaptor MM1548 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 v cc 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 v cc and out exceeds v lsp1 (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 ( v lsp1 ) or decreasing ( v lsp2 ). ( hysteresis: v lsp1 = 200mv < > v lsp2 = 115mv) when the differential voltage between v cc and out falls to v lsp2 (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 v cc 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 v cc 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 v cs1 (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 v cs1 . 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 v cc voltage keeps 5.1v (equal to internal 1.25v: ref voltage). voltage between v cc and out(200mv) r l s 470 ? r l b 100 ? supply transistor cnt load current v cc 200mv 200mv 115mv energy saving mode normal mode input/output difference control load current detection energy saving current detection po1 drive po1 drive(load 5k ? ) photocoupler pc1 control po1 out pc1 output ( ) gnd rcs cs 0.22 ? load ( + ) voltage drop detection (v=4.6v) voltage drop detection (v cc =3.5v) constant voltage control (v cc =5.1v) constant current control (cs=114.4mv) (io=520ma) ros1 ros2 ref overvoltage detection (v cc , out = 7v) energy saving mode control (3.5v :on , 5.1v :off) photocoupler-turn-off(4.6v ) operation
mitsumi secondary control for energy-saving ac adaptor MM1548 1.6 overvoltage detection when v cc 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. 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 (vo = 5.1v) = {1+(2460k/800k)} 1.25 ?0.2 ( vls = 0.2v) = 4.9v [a] c v mode (po1:control) cc mode (po1:control) vcs(115mv typ.) energy saving mode (po1:open) energy saving current detection (load detection release ) load current detection cc mode drop curve (po1:control) 114.4mv/rcs (115mv/r l s) (200mv/r l s) 34mv/rcs load current vo(5.1v typ.) vls(0.2v typ.) output voltage (between out and cs) [v]
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] = v cs1 / rcs (v cs1 = 114.4mv) [drop curve] = v cs2 / rcs (v cs2 = 34mv) 200 300 400 500 600 700 800 900 1000 1100 1200 i= (vcs1) / rcs rcs(constant current detection resistor) - constant current control value constant current control value [ma] rcs(constant current detection resistor) [ ? ] 0.1 1.0 min. typ. max. 0.22 ? 2.3 description of load detection and energy saving detection (r l s adjust method) load detection current and energy saving detection current is set by r l s as load detection resistor. on the design, each current changes when [current flows through r l s] > 240?, in the case of 470 ? use. [formula] [load detection current] = ( v lsp1 / r l s) ( v lsp1 = 200mv) [energy saving detection current] = ( v lsp2 / r l s) ( v lsp2 = 115mv) 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 i= ( v lsp2 ) / rls r l s (load detection resistor) - energy saving detection current energy saving detection current [ a] r l s (load detection resistor) [k ? ] 0.1 10 1 min. typ. max. 470 ?
mitsumi secondary control for energy-saving ac adaptor MM1548 5.1v 4.9v v cc out 0v 0ma on off 5.1v 4.9v 3.5v v cc out 0v 0ma on off v cc , out pin (secondary side output) 1 po1 current (load det. + constant voltage control output) 3 primary side switching 4 2 normal mode normal mode energy saving mode energy saving mode normal mode constant voltage control normal mode [io>115mv / r l s] energy saving mode [io<115mv / r l s] 2v out 0v 0ma on 114.4mv 0mv 200mv off 2v out v cc 0v 0ma on 0mv 34mv over 0.6v off v cc , out pin (secondary side output) 1 po1 current (load det. + constant voltage control output) 3 primary side switching 4 cs terminal (constant current control input) 5 2 constant current control normal control [v cc >2.0v] drop control [v cc <2.0v] ac input output delay circuit switching interruption control switching circuit smoothing circuit MM1548 + signal detection circuit photocoupler r l s v cc cnt out po1 gnd cs rcs 4 1 2 3 5 rectifying circuit timing chart
mitsumi secondary control for energy-saving ac adaptor MM1548 timing chart 1 v cc pin 2 out pin 3 po1 pin 4 cnt pin 5.1 v 4.9v 0v open open 115mv 200mv v cc out low(load 5k ? ) control 0ma 5 load current load detection current (200mv/r l s) energy saving current (115mv/r l s) load current decrease 5 load current 1 v cc pin 2 out pin 3 po1 pin 4 cnt pin load current increase load detection current (200mv/r l s) energy saving current (115mv/r l s) 5.1 v 4.9v 0v open open 200mv v cc out low(load 5k ? ) control 0ma load current increase ac input rectifying circuit delay circuit switching interruption control switching circuit smoothing circuit MM1548 output + signal detection circuit photocoupler rls v cc cnt out po1 gnd cs rcs 4 3 5 2 1 load / energy-saving detection load current decrease
mitsumi secondary control for energy-saving ac adaptor MM1548 application circuit input ac100v output + dc4.9v 520ma ph1 10 r20 d1 l1 r1 6.8 c6 0.22 c2 4.7 470 220 220 0.22 4.7 0.1 c12 1m 2.2m 3.3m 100k r3 270k r4 r7 r8 c4 c5 1.5m r5 c7 d4 c8 c9 r18 100 r11 10k 1000p r13 10k r2 q2 q3 q4 r12 10k 470 r10 470 r9 4700p c3 r14 100k d2 q6 q1 d3 c13 0.0056 l2 470 r15 q5 470 r17 0.22 r16 c10 r19 10 v cc cnt out po1 gnd cs mm 1548 t1 c11 2200p

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