2
ADC 3
6
15
LED 22
23
1000 ADC ( 3 )
IC1
0.1µF
16.2kΩ IC3ADC 1
REFOUT
REFIN
REFP
REFN
COM
IC4ADC N
REFOUT
REFIN
REFP
REFN
COM
N.C.
N.C.
IC2162Ω
100µF
0.1µF 0.1µF0.1µF
1µF
0.1µF 0.1µF0.1µF
2.048V
10Hz LOWPASSFILTER
+
-
10Hz LOWPASSFILTER
2.2µF10V
0.1µF
NOTE: ONE FRONT-END REFERENCE CIRCUIT DESIGN MAY BE USED WITH UP TO 1000 ADCs.
3V
0.1µF
0.1µF
0.1µF
5
2
3
4 1
1
2
3
29
2
1
32
31
29
2
1
32
31
3V
LOW-NOISE REFERENCE CIRCUIT
ADC
(ADC)
ADC
ADC
ADC 16
24 32
ADC
ADC
• ADC
• ADC
( ADC
)
• ADC
ADC
( )
ADC
ADC
ADC
ADC
(FS)
ADC
ADC
ADC
ADC
ADC
ADC
10 ADC
MAX1448 ( 60dB)
-60dBFS 1Hz
80MHz
40MHz √40MHz = 76dB ADC
-60dBFS-76dBFS = -136dBFS
20dB (-156dBFS)
2.0V 33nVP-P (
8nVRMS /√Hz)
ADC
( MAX144x
±1%)
ADC
3
4
MAX144x (IC3 IC4)
REFIN
REFIN (
REFIN )
MAX6062 (IC1) 2.048V
( 1) 150nV/√ Hz
( 10Hz)
MAX4250 (IC2)
10Hz IC2
( )
10Hz
ADC
MAX144x ±4.4% (
±0.5dB)
/
ADC
( 2 )
MAX144x REFIN
A D C
0.1% ( ) ADC
4kΩ ADC
MAX6066 (IC1) 2.500V
10Hz
2.0V 1.5V 1.0V
1. 1000 ADC
IC1
0.1µF
16.2kΩ IC3ADC 1
REFOUT
REFIN
REFP
REFN
COM
IC4ADC N
REFOUT
REFIN
REFP
REFN
COM
N.C.
N.C.
IC2162Ω
100µF
0.1µF 0.1µF0.1µF
1µF
0.1µF 0.1µF0.1µF
2.048V
10Hz LOWPASSFILTER
+
-
10Hz LOWPASSFILTER
2.2µF10V
0.1µF
NOTE: ONE FRONT-END REFERENCE CIRCUIT DESIGN MAY BE USED WITH UP TO 1000 ADCs.
3V
0.1µF
0.1µF
0.1µF
5
2
3
4 1
1
2
3
29
2
1
32
31
29
2
1
32
31
3V
IC2
10Hz
3nV/√Hz 2.0V 1.0V
ADC 2VP-P 2.0V
1.0V ADC
4kΩ ADC 32
ADC 8mA
IC2
IC1
ADC
0.1% ( ) 100Hz
3nV/√ Hz 1
0.1%
32 ADC
32 ADC
ADC MAX144x 10
ADC
( 1/24/02 EDN )
5
2. 32 ADC
IC1
0.1µF
21.5kΩIC3
ADC 1
REFOUT
REFIN
REFP
REFN
COM
IC4ADC 2
REFOUT
REFIN
REFP
REFN
COM
N.C.
N.C.
IC2A47Ω
330µF6V
0.1µF 0.1µF0.1µF
1µF
0.1µF 0.1µF0.1µF
2.2µF10V
0.1µF
NOTE: ONE FRONT-END REFERENCE CIRCUIT DESIGN MAY BE USED WITH UP TO 32 ADCs.
IC2C
IC2B
330µF6V
330µF6V
21.5kΩ
21.5kΩ
21.5kΩ
21.5kΩ
1.47kΩ6V
10µF
10µF
6V
47Ω
1.47kΩ
1.47kΩ
47Ω
10µF6V
+
+
+
-
-
-
3V
3V
3V
2V
1.5V
1.0V1.0V AT -8mA
1.5V AT 0
2.0V AT 8mA
3V
0.1µF
MAX4254 POWER-SUPPLY BYPASSING.PLACE CAPACITOR AS CLOSE ASPOSSIBLE TO THE OP AMP.
1
3
2 3
2
4
11
1
4
11
11
4
5
67
10
98
29
2
1
32
31
29
21
32
31
3V
1. Maxim MAX1444 Rev. 0, 10/00.2. Maxim MAX1448EVKIT Rev. 1, 12/01.3. Maxim MAX4249–MAX4252 Rev. 4, 1/02.4. Maxim MAX6061–MAX6068 Rev. 1, 5/01.
(36V 75V) 48V
5W
MAX5021
MAX5021 IC PWM
262kHz
IC
(
) MOSFET
1
36V 72V 5W
1:2 5W
6
1. MAX5021 PWM 5V 5W
R182Ω
R624.9kΩ
R78.06kΩ
R8510Ω
R1051Ω
R3100Ω
CS1
GND 2
NDRV3
VCC4
VIN5
OPTO6
U1
C5330µF,
10V
C31nF
C40.22µF
C6220µF
C710nF
C80.22µF
C910µF
C10560pF
D1
MMBD914
D3 BAS21LT1
R117.5kΩ
R1247kΩ
7
5
6 1
2
U3MOC207
C11µF,100V
5
3
4
U2TLV431AC
NS_A
C112.2µF, 250VAC
T1
EPC13-CTX03-15498 COOPERL2
120Ω AT 100MHz
L12kΩ AT 100MHz
1J3
+VOUT
1
J4
COM
1J1
48 VIN
1J2
GND
Q1IRF5802
D2 MBRS340
5V, 1A
R91.3Ω
R41.3Ω
MAX5021
C21µF,100V
R5249kΩ
7
(
) (
)
/
RMS
IC
MOSFET
MAX5021 MOSFET
15W
( RMS
)
MAX5021 40˚C
•
•
•
•
•
• AL
• RMS RMS
•
1)
η =
KP = ( 0.5)
KT = RMS (
0.55 0.65)
KU = (0.4 0.5)
J = (9.862 x 106A/m2
40˚C)
BMAX = (
0.12T 0.15T)
(AP)
AP
(Ae)
( 13 )
2)
A(1.1 P D )
K K J K BPOUT MAX
P U MAXT SW MIN)≥ × ×
× × × × × × ƒη (...( )m
4
AP
BPOUT
MAX
m≥−× ×
×( )
...( )2 10 12
4
η
LV V D
IHS
O D OFF MIN
OUT SW MAX
≤ + ×× × ƒ
( ) ( )...( )( )
( )
2
2
LV V
IHS
O D
OUT
≤ × × +−430 10 9 ( )...( )
5 8
3 4
2
(W)
9 12
EPC-13
EEM-12.7
EPC-10
EPD-15
145
90
30
AP (mm4)
216
12.5
12
9.4
Ae (mm2)
13.5
VD = ( )
IOUT = ( )
3)
4)
V-s
Ae = ( )
5)
0.2V 0.7V
6) AL MOSFET
7)
RMS
28AWG
RMS 50% (
)
RMS
10mA
8)
MOSFET
MOSFET /
RMS (
) MOSFET
( 2
) MOSFET VDS
( )
8
LV D
PPIN MIN MAX
OUT S MAX=
× ×× × ƒ
( )
( )
2 2
2
η
LV
PHP
IN MIN
OUT
= × × ×−0 4 10 6 2....( )( ) η
NV D
A BPIN MIN MAX
e MAX S MIN
= ×× × ƒ
( )
( )
NV
A BPIN MIN
e MAX
= × ××
−2 1 10 6. ( )
N NL
LS PS
P
= ×
NVBIAS
OUT
=+
11 7
0 2
.
.
AL
N
nHL
P
P
= ×2
9210 ...
IP
D V
DAPRMS
OUT
MAX IN MIN
MAX=× × ×
×0 5 3.
...( )( )η
IP
VAPRMS
OUT
IN MIN= ×
×1 63.
...( )( )η
II
D
DASRMS
OUT
OFF MAX
OFF MAX=×0 5 3.
...( )( )
( )
I I ASRMS OUT= ×1 63. .....( )
V VN
NV V V VDS MAX IN MAX
P
SOUT D SPIKE( ) ( ) ( ) ...( )= + × + +
9
VDS
RDS(ON)
NP/NS
VDS(MAX) / / (RCD)
RMS MOSFET
MOSFET
MOSFET
MOSFET
QG = MOSFET ( )
VCC = ( )
tOFF = ( )
CDS = ( )
RCD
MOSFET VDS
RCD
MOSFET
MOSFET
LL = (
1µH 3µH ) VSPIKE =
30V 50V IPK =
( ) RSENSE
MOSFET VDS(MAX)
RC 2 3
DMIN = = DMAX/2 (
50% )
RMS
ESR
ESR
2. 1 VIN = 36V VOUT =
5V IOUT = 1A MOSFET(Q1) (
) 5 0 V / d i v ( )
0.65A/div
P R IMOS DS ON PRMS= × × +( . )( ) 1 4
Q VV I t
G CC S MAXIN MAX PK off S MAX× × ƒ +
× × × ƒ( )
( )( )
( ) ( )
4
CL I
VFL PK
SPIKE
=× 2
2...( )
P C VR SNUBBER SPIKE= × × × ƒ ( )(1
22
S MAX)
V VNN
D
R
O DP
SMIN
SNUBBER
++ × × −[( ) ] ( )12
1µs/div
C VWDS DS S MAX+
× × ƒ( )...( )( )
2
2
DRAINVOLTAGE
50V/div
PRIMARYCURRENT0.65A/div
ESR
ESR (∆VESR)
(∆VC)
ESR ESR
3:1
ESR
RMS
( 3)
RMS
E S R
(∆VESR)
(∆VC) MAX5021
ESR
ESR
ESR
DOFF
di/dt ESL
LC
4 LC
1µF 10µF ESR
fC =
MAX5021
MAX5021
10
CP
V VFIN
OUT
IN MIN C= × ×
× ×
−4 10 6
η ( )...( )
∆
ESRV
IINESR
PK
= ∆ Ω....( )
CD I
VFOUT
OFF O
C
= × − × × −4 1 10 6( )...( )
∆
ESRV
IOESR
O
= ∆ Ω...( )
DI L
V VOFFO S
O D
= ×× × +−2 10 6 ( )
LC
HC
≤× × ƒ ×
1
4 103 2...( )
IP
VACRMS
OUT
IN MIN= ×
×1 63.
...( )( )η
1µs/div
3. 1 VIN = 72V VOUT =
5V IOUT = 1A
500mV/div ( ) 50V/div (
)
DRAINVOLTAGE
50V/div
INPUT-VOLTAGE
RIPPLE500mV/div
11
MOSFET
MOSFET
( 5) MOSFET
QG = MOSFET ( )
VCC = VCC (MAX5021 4);
tF = ( )
VD = ( )
fSW = (262kHz)
IPK = ( )
VFB
VFB = ISPK/2 ( )
(RHP)
-
RHP
MAX5021
PWM
PWM ESR
PWM
ESR
(fP)
4. 1 VIN = 72V VOUT =
5V IOUT = 1A LC
( 100mV/div)
( 200mV/div)
5. 1
EFFICIENCY vs. OUTPUT CURRENT
IOUT (A)
EFFI
CIEN
CY (%
)
1.00.80.2 0.4 0.6
45
50
55
60
65
70
75
80
85
400 1.2
72VIN
48VIN
36VIN
P R IMOS DS ON PRMS= ×( . )( )1 4
P V ID FB O= ×
Q VI V t
G SW CCPK D F SW+ × ƒ × +
× × × ƒ( ) ( )
6
A
R L
R RCTRPWM
L P SW
S LED
=
× × ƒ ×
× × ×
η2 6 2 103.
APWM =
× × × × ×
× × ×
−5 61 10 262 10 0 82
0 65
6 2 10
5101
6 3
3.
.
.
APWM =105
2µs/div
OUTPUTRIPPLE
WITHOUTLC FILTER200mV/div
OUTPUTRIPPLE
WITHLC FILTER100mV/div
ƒ =× × ×P
L OR CHz
1
2 π...( )
ƒ =× × × × −P Hz
1
2 5 330 10 6π...( )
ƒ =P Hz96...( )
12
ESR (fZ)
RL =
CTR =
RS =
CO =
PWM (APWM)
( )
(PM)
PWM
-1
ESR
(fZE) (fPE)
8kHz
44˚ 6 1
(20µs 100mA 1A)
( 7)
8
6. 1
100 1k 10k 100k
CLOSED-LOOP RESPONSE
FREQUENCY (Hz)
GAIN
(dB)
PHAS
E (D
EGRE
ES)
80
-40
-20
0
20
40
60
180
-180
-135
-45
45
-90
90
135
0
GAIN
PHASE
ƒ =× × ×z
OC ESRHz
1
2 π...( )
ƒ =× × × ×−z Hz
1
2 330 10 0 066π .....( )
ƒ =z Hz8038....( )
ƒ =× × ×ƒ ƒ
ZE R CHz
1
2 π...( )
ƒ =× × × × × −ZE Hz
1
2 47 10 10 103 9π...( )
ƒ =ZE Hz338...( )
7. 1 IOUT 1A/div ( ) VOUT
100mV/div ( )
ƒ =× × ×ƒ ƒƒ
PE R CHz
1
2 π....( )
ƒ =× × × × × −PE Hz
1
2 47 10 220 103 12π....( )
ƒ =PE Hz15 392, ....( )
50µs/div
OUTPUTCURRENT
1A/div
OUTPUTVOLTAGE
100mV/div
•
MOSFET
• MAX5021 MOSFET
• RCD
MOSFET
• MAX5021 VCC VIN CS
IC
•
• MOSFET
(SELV TNV-1 TNV-2 TNV-3)
( )
Underwriters Laboratory UL60950
VIN = 36V 72V VOUT = 5.1V IOUT =
1.1A
(AP)
EPC13 (TDK PC44EPC13-Z)
AP Ae
(LS)
(LP)
(NP)
NP = 48
13
8. 1
48V ( 20V/div) 1A 5V
( 2V/div)
AP
BmP
OUT
MAX
≥ × ××
−( )...( )
2 10 124
η
A mP ≥ × ××
−( . )
. ....( )
2 5 61 10
0 8 0 12
124
A mP ≥ × −117 10 12 4....( )
A mP = × −145 10 12 4....( )
A me = × −12 5 10 6 2. ....( )
LV V
IHS
O D
OUT
≤ × × +−430 10 9 ( )...( )
S ≤ × × +−430 10 5 1 0 4
1 1
9 ( . . )
....( )H
L HS ≤ × −2 15 10 6. ...( )
LV
PHP
IN MIN
OUT
= × × ×−0 4 10 6 2....( )( ) η
P = × × ×−0 4 10 34 0 8
5 6
6 2. .
....( )H
L HP = × −65 10 6....( )
2ms/div
OUTPUTVOLTAGE
2V/div
INPUTVOLTAGE
20V/div
NV
A BPIN MIN
e MAX
= × ××
−2 1 10 6. ( )
P = × ×× ×
−
−2 1 10 36
12 5 10 0 12
6
6.
. .
P = 47 6.
14
(NS Nbias)
NS = 9
Nbias = 20
RMS (IPRMS ISRMS)
N NL
LS PS
P
= ×
S = 8 7.
NV
NbiasOUT
S=+
×11 7
0 2
.
.
Nbias =19 8.
AL
NnH
LP
P
= ×2
9210 ...
AL = 26...nH
2
IP
VAPRMS
OUT
IN MIN
= ××
1 63.....( )
η
IPRMS = × ××
1 63 5 1 1 1
0 8 34
. . .
.....( )A
I APRMS = 0 33. ....( )
I I ASRMS OUT= ×1 63. ....( )
I ASRMS =1 79. ....( )
(APD)
(PZT)
(VFD) (MEMS)
( 1a 1b
1c)
APD (75V)
3V
• MOSFET 3V
• MOSFET
1/2 fswitch x CDSVOUT2
• MOSFET
IC
MOSFET
•
1c
MOSFET
MAX1605 28V MOSFET
6mm x 8.5mm ( 8
DIP ) ( 2)
DC-DC
1c
(
)
LX MOSFET
•
•
• MOSFET
1a 1b 1c DC-DC
NS
GND
NCONTROL
LOGIC
VCCILIM LX
FB
VOUT = VIN
2.5V TO 5.5V
MAX1605
NP
D1
COUT
GND
VCCILIM LX
FBBOOST CONVERTER
NODE 1
VCCILIM LX
FBFLYBACK
CONVERTER
VIN VINVOUT VOUT
A SMALL 6-PIN SOT23 WITH INTERNAL FET CONVERTS 2.5V TO 130V OR MORE THAN 6mA AT 75V.
T1
6-PINSOT23
75V AT MORE THAN 6mA
Figure 1a Figure 1b Figure 1c
15
2. MAX1605 6mm 8.5mm DC-DC 2.5V
75V
16
MOSFET
•
•
•
MAX1605
MOSFET
1a MOSFET
MOSFET
LX VOUT + VD
1/n
(VOUT) (VIN) n
D 3
VIN
1 1b 1a
1:1
1
LX
1 LX
1c
MOSFET MOSFET
MOSFET
1b LX
LX N x I
P S initial
MOSFET final
MOSFET
3. 1a
IL
VINLBST
VOUT - VINLBST
D x T
T
STEADY-STATE CURRENT RIPPLE FOR VIN = 2.5V AND VOUT = 50V
IPK
dIdt
=
dIdt =
0
IINMAX
IOUTMAX
V
V DOUT
IN
=−1
1
∆ ∆I IUP DOWN=
∆IV
Lt
V
LD TUP
IN
BSTON
IN
BST
= = ×
∆IV V
Lt
V V
LD TDOWN
OUT IN
BSTOFF
OUT IN
BST
= − = − − ×( )1
V
LD T
V V
LD TIN
BST
OUT IN
BST
× = − − ×( )1
V D V V DIN OUT IN× = − × −( )1
V
V DOUT
IN
=−1
1( )D
V
VIN
OUT
= −1
I N I N I N I NP initial P S initial S P final P S final S_ _ _ _× + × = × + ×
V V
V N N VPRIMARY IN
SECONDARY S P
== ×
−
/ PRIMARY
17
IS_initial = IP_final = 0
1c IP_final = IS_final
‘N’
1c
N
1c
4 1c
2
LBST
4
LBST N IPK/N
IPK N
:
LTOT LP
LTOT N2 LTOT LBST N
LP LBST/N
4
∆ I U P
∆IDOWN ∆IUP ∆IDOWN
VOUT/VIN
3 4
( ) 3 4
1/2L x I2 ( 4 L N
I N ) 1c
N
1c
4 1c
N N
IPK/N
ISAT N N
N
N
( )
IN
N NIS final
P
P SP initial_ _=
+
NN N
NP S
P
= +
4. 1c
dIdt
=IL
STEADY-STATE CURRENT RIPPLE FOR VIN = 2.5V and VOUT = 50V
VIN x N2
LTOT
IOUTMAX
N
t
VOUT - VIN
dIdt
=
MOSFET SWITCHES OFF
LTOT IINMAX
tON = D X T
tOFF = (1 - D) x T
IPK
IPK
LL
NPTOT= 2
I I NSAT PK= /
L L N L NP TOT BST= =/ /2
L L NTOT BST= ×
∆I IUP PK= ∆ ∆I
I
N
I
NDOWNPK UP= =
∆IV
Lt
V
L ND TUP
IN
PON
IN
BST
= = ×/
∆IV V
Lt
V V
L ND TDOWN
OUT IN
TOTOFF
OUT IN
BST
=−
=−×
− ×( )1
V V
L ND T
V
L N ND TOUT IN
BST
IN
BST
−×
− × =×
×( )/
1
V
V
N D
DOUT
IN
= ×−
+1
1 DV V
V N VOUT IN
IN OUT=
−− +( )1
IN
NIS final
P
SP initial_ _=
18
/
L = LBST I = IPK 1c
L = LBST N I = IPK/N
∆VOUTA ∆VOUTC
1c 1c
1/N N
5 1a 1c
( 50%)
N
/
MOSFET (
tRR)
ER_LOSS
Edelivered
D R
1a 1c
Lleakage
Toko D32FU 680µH/
12
2 12
2 12
2LI C V C VOUT final OUT initial= −
12
2 12
LI C V V V VOUT final initial final initial= − × +( ) ( )
12
2LI C V VOUT OUT OUT= ×∆
∆VLI
C VOUTOUT OUT
=12
2
∆VL I
CVOUTABST PK
OUT
=12
2( )
∆ ∆V
N LIN
CV
V
NOUT C
BSTPK
OUT
OUTA=×
=12
2( )
5. 1a 1c
CAPACITIVE RIPPLE
BOOST WITH TRANSFORMER LEVERAGE
STANDARD BOOST
ESR RIPPLE
E
E ER LOSS
R LOSS delivered
_
_
%+
×100
13
13
12
100I R
I R V
PK
PK IN+× %
L
L Lleakage
leakage primary+×100%
19
74mA/20Ω/3.5mm x 3.5mm x 2.2mm
1:9
6.8µH/740mA/
2Ω N2 ( N
) 1:9
10
N 10 N
N
N
6 75V APD
6 SOT23 MAX1605
IC 28V/500mA MOSFET
VIN + VOUT - VIN /N =
17V
7 MAX1605
( 5%
)
1c
LP IPK
(500mA) COUT (0.47µF) VOUT
75V 16mVP-P
1a
16mVP-P
APD
RC LC RC
(
)
100V
( ) 8
ß VBE
VOUT
ß
6. 2 2.5V 75V
GND
N
LIM LX
FB
VOUT = 75V AT MORE THAN 6mA
VIN2.5V TO 5.5V
MAX1605
NP
D1
COUT
T1
SHDN
SUMIDA CMD4D13 4365-T020,NP:NS IS 1:5, LP = 4.53µH
IP_SAT = 562mA, RP = 0.852ΩSIZE IS 4.1mm x 4.3mm x 1.45mm
13.7kΩ
470pF
0.47µF 100V CERAMIC CAPACITOR IN 1210 CASE(TDK C322X7R2A474K)
CENTRAL SEMICONDUCTORCMOD4448 BK SOD-523
0.47µF
VCC
NS 750kΩ
CONTROL LOGIC
7. 6
120110100908070605040
2
4
6
8
10
030 130
MAXIMUM LOAD vs. OUTPUT VOLTAGE
OUTPUT VOLTAGE (V)
MAX
IMUM
LOA
D (m
A)
VIN = 2.5V
VIN = 3.3V
VIN = 5V
VL I
C VRIPPLEP PK
OUT OUT
=×
×
12
2
20
• MOSFET
•
•
•
MAX668
9
MOSFET
MAX668 MOSFET
48nC IRF7401 MOSFET
150V
MAX668
• Coilcraft DO1813P-472HC
4.7µH/2.6A/0.054Ω• ES1D 200V 15ns
• MOSFET IRF640NS 200V 0.15ΩQG = 67nC, CDSS = 185pF, 5.5V
2A
• 50mΩ
FB
FB
150V 6V
150V
18mA (2.7W) 6V
(65%) ( )
91mA
MOSFET 10
1c
( 11)
Sumida CMD-8LN 6313-T036,
LP = 5.6µH, IP = 2.3A, NP:NS= 1:9,
RP = 0.5Ω
1 9 22V
MOSFET 30V
MOSFET ( 200V MOSFET)
150V 25.5mA (3.8W) 77%
88% ( 15mA )
1.8mA
200V MOSFET
200V MOSFET
1:9 2kV
>1kV
Central Semiconductor 400V CMR1U-04
(50ns tRR) ES1D
400V
ES1D 346V
MOSFET -9 x VIN
VOUT = 330V 9.6mA (3.1W)
60% 66% (
4mA)
8.
RFILTER
CFILTER
OUT
FILTERED OUT
9.
PGND
N1IRF7811W
VCCLX
VIN = 5V
MAX668
NP
D1
COUTFOUR 0.1µF 250VCERAMIC CAPACITORS
T1
SYNC/SHDN
CEE98 6343-T361,NP:NS is 1:9, LP = 2.4µH, IP_SAT = 7A, RP = 0.055ΩSIZE IS 8.2mm x 9.5mm x 6.0mm
ES1D ULTRA-FAST, 200V, 15ns DIODE
68µF
CSEXT
FBGND
220pF
FREQR4
121kΩ
R150mΩ
R210MΩ
VOUT
VADJ
R375kΩ
NS
150V 30V MOSFET
IRF7811W (30V/0.012Ω/QG =
18nC/CDSS = 500pF) IRF640NS
( 0.15Ω 0.012Ω)
25.7mA (150V)
82.3% ( 77%) 88% (15.5mA)
12
( )
MOSFET
0.5Ω
IPSAT = 5A LP = 1.7µH
2
MOSFET
IRF7811W
MOSFET MOSFET
21
10. ( ) ES1D 15ns ( )
INDUCTOR CURRENT500mA/div
0
VLX50V/div
0
MOSFET IS ON
INDUCTOR CURRENT SLEWS CLX DPWN
DIODE ISCONDUCTING
CHARGE INTO OUTPUT
CHARGE OUT OF OUTPUT
0.8A REVERSE-INDUCTOR CURRENT
MOSFET BODY DIODECLAMPS NEGATIVE
CURRENT
20ns/div400ns/div
ZOOM OF NO-LOAD SWITCHING WAVEFORMNO-LOAD SWITCHING WAVEFORM FOR AN INDUCTOR SOLUTION
INDUCTOR CURRENT SLEWS CLX UP
ILPRIM0.5A/div
VLXI20V/div
OUTPUT RIPPLEAC-COUPLED
200mV/div
O
O
12. DC-DC
DC-DC
EFFICIENCY vs. LOAD
LOAD (mA)
EFFI
CIEN
CY (%
)
2015105
10
20
30
40
50
60
70
80
90
100
00 25
INDUCTOR-BASED, 200V MOSFET, 150V OUTPUT
TRANSFORMER-BASED, 30V MOSFET, 150V OUTPUT
TRANSFORMER-BASED, 200V MOSFET, 150V OUTPUT
TRANSFORMER-BASED, 200V MOSFET, 330V OUTPUT
11. MAX668 9 150V
DC-DC
22
DESIGN SHOWCASE
LEDLCD
(CCFL)
(EL)
LED
LED LED
LED 3.5V ±10%
LED
LED
LED
( )
LED
1
/
µMAX (U1) 100mA
LED
LED
U1
SHDN
(POK)
RC π
40mVP-P (VIN = 3.6V)
(0.22µF)
400mVP-P
( 3/5/01 Electronic Design )
U1
MAX1759
SHDN
PGND
7
6
8
3,4
2 1
10
9
5
0.22µF
0.22µF
To µC
1µF 1µFIN OUT
FB
POK
CXPCXN
IN1Ω
16ΩOFF
ON
GND
WHITE LED
1. IC
LED
23
( 1)
V2/RCOIL
5V
( )
( )
3.5V 1.5V
2.5V 1
1
SW1 C1 C2
RC C2
C1
C2 C1 2.5V
5V ( )
C1
2.5V D1
(1.5V)
R1 C1
C1
(U1) 400mA
IPEAK = (VIN - VD1) /(R1 + RON)
RON ( 1.2Ω)
C1 VIN
C1
R2 C2 C1 C2
C1
C2R2 C1 (R1 + RON)
C2R2
( 12/20/01 EDN )
DESIGN SHOWCASE
MAX4624
U1
D1
+
1
2
3
45
6
R14.7Ω
R227kΩ
C20.15µF
C1100µF
D2
SW1
VIN = 2.5V
1.
1.
45
63
90
(mA)
2.5 ( )
3.5
( )
5 ( )
(V)
250
221
450
(mW)