General Description The MAX742 DC DC converter is a controller for dual out put power supplies in the 3W to 60W range Relying on simple two terminal inductors rather than transformers the MAX742 regulates both outputs independently to within over all conditions of line voltage temperature and load current

Max Over

Description

Niveau: Secondaire, Lycée, Terminale
_______________General Description The MAX742 DC-DC converter is a controller for dual-out- put power supplies in the 3W to 60W range. Relying on simple two-terminal inductors rather than transformers, the MAX742 regulates both outputs independently to within ±4% over all conditions of line voltage, temperature, and load current. The MAX742 has high efficiency (up to 92%) over a wide range of output loading. Two independent PWM current- mode feedback loops provide tight regulation and opera- tion free from subharmonic noise. The MAX742 can operate at 100kHz or 200kHz, so it can be used with small and lightweight external components. Also ripple and noise are easy to filter. The MAX742 provides a regulated output for inputs ranging from 4.2V to 10V (and higher with additional components). External power MOSFETs driven directly from the MAX742 are protected by cycle-by-cycle overcurrent sensing. The MAX742 also features undervoltage lockout, thermal shut- down, and programmable soft-start. If 3W of load power or less is needed, refer to the MAX743 data sheet for a device with internal power MOSFETs. ________________________Applications DC-DC Converter Module Replacement Distributed Power Systems Computer Peripherals _________________________

• load current


• noise without


• applications dc-dc


• dual output


• pump


• charge-pump load


• duty-cycle limit

Sujets

• Première
• Régulation

Informations

• Publié par: profil-zyan-2012
• Nombre de lectures: 30
• Langue: English

Extrait

19-3105; Rev 2; 8/96

Switch-Mode Regulator with
+5V to ±12V or ±15V Dual Output
_______________General Description____________________________Features
The MAX742 DC-DC converter is a controller for dual-out-
©
Specs Guaranteed for In-Circuit Performance
put power supplies in the 3W to 60W range. Relying on
©
Load Currents to ±2A
simple two-terminal inductors rather than transformers, the
©
4.2V to 10V Input-Voltage Range
MAX742 regulates both outputs independently to within
±4% over all conditions of line voltage, temperature, and
©
Switches From ±15V to ±12V Under Logic Control
load current.
©
±4% Output Tolerance Max Over Temp, Line,
The MAX742 has high efficiency (up to 92%) over a wide
and Load
range of output loading. Two independent PWM current-
©
90% Typ Efficiency
mode feedback loops provide tight regulation and opera-
©
Low-Noise, Current-Mode Feedback
tion free from subharmonic noise. The MAX742 can
©
Cycle-by-Cycle Current Limiting
operate at 100kHz or 200kHz, so it can be used with small
©
Undervoltage Lockout and Soft-Start
and lightweight external components. Also ripple and
noise are easy to filter. The MAX742 provides a regulated
©
100kHz or 200kHz Operation
output for inputs ranging from 4.2V to 10V (and higher with
______________Ordering Information
additional components).
External power MOSFETs driven directly from the MAX742
PARTTEMP. RANGEPIN-PACKAGE
are protected by cycle-by-cycle overcurrent sensing. The
MAX742
CPP0°C to +70°C20 Plastic DIP
MAX742 also features undervoltage lockout, thermal shut-
MAX742CWP0°C to +70°C20 Wide SO
down, and programmable soft-start.
MAX742C/D0°C to +70°CDice*
If 3W of load power or less is needed, refer to the MAX743
MAX742EPP-40°C to +85°C20 Plastic DIP
data sheet for a device with internal power MOSFETs.
MAX742EWP-40°C to +85°C20 Wide SO
MAX742MJP-55°C to +125°C20 CERDIP
________________________Applications
* Contact factory for dice specifications
DC-DC Converter Module Replacement
__________Simplified Block Diagram
Distributed Power Systems
V5+Computer Peripherals
INPUT
MAX742
-CC__________________Pin Configuration
TOP VIEW

FB+120CSH+
CC+219CSL+
AGND318GND
AV417EXT+
100/2005
MAX742
16PUMP
12/15615PDRV
VREF714EXT-
SS813V+
CC-912CSH-
FB-1011CSL-
DIP/SO

+V2R.E0FV

+CC

R-SENSE
MWPS-DRIVEP
CSOS+DRIVEN
MWPR+SENSE

OV-OV+

________________________________________________________________Maxim Integrated Products1
For free samples & the latest literature: http://www.maxim-ic.com, or phone [phone]

Switch-Mode Regulator with
+5V to ±12V or ±15V Dual Output
ABSOLUTE MAXIMUM RATINGS
V+, AV+ to AGND, GND.........................................-0.3V to +12VContinuous Power Dissipation (any package)
PDRV to V+.............................................................+0.3V to -14Vup to +70°C.....................................................................500mW
FB+, FB- to GND..................................................................±25Vderate above +70°C by..........................................100mW/°C
Input Voltage to GNDOperating Temperature Ranges
(CC+, CC-, CSH+, CSL+, CSH-, CSL-,MAX742C_ _.......................................................0°C to +70°C
SS, 100/200, 12/15)..................................-0.3V to (V+ + 0.3V)MAX742E_ _....................................................-40°C to +85°C
Output Voltage to GNDMAX742MJP..................................................-55°C to +125°C
(EXT+, PUMP)..........................................-0.3V to (V+ + 0.3V)Storage Temperature Range.............................-65°C to +150°C
EXT- to PDRV................................................-0.3V to (V+ + 0.3V)Lead Temperature (soldering, 10sec).............................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

ELECTRICAL CHARACTERISTICS
(Circuit of Figure 2, +4.5V < V+ < +5.5V.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
Output Voltage, ±15V Mode0mA < I
L
< 100mA, T
A
= +25°C14.5515.45V
(Notes 1, 2)12/15= 0VT
A
= T
MIN
to T
MAX
14.4015.60
Output Voltage, ±12V Mode0mA < I
L
< 125mA, T
A
= +25°C11.6412.36V
(Notes 1, 2)12/15= V+T
A
= T
MIN
to T
MAX
11.5212.48

ELECTRICAL CHARACTERISTICS
(Circuit of Figure 2, V+ = 5V, 100/200= 12/15= 0V; T
A
= T
MIN
to T
MAX
, unless otherwise noted.)
PARAMETERSYMBOLCONDITIONS
Line RegulationV+ = 4.5V to 5.5V, PDRV from PUMP
Load Regulation (Note 2)I
LOAD
= 0mA to 100mA
No EXT- or PUMP load,V+ = 5V
No-Load Supply CurrentFB+ = FB- = open circuitV+ = 10V
Undervoltage LockoutUVLO
Undervoltage Lockout Hysteresis
Reference Output Voltage
Oscillator Frequencyf
OSC
100/200= 0V
100/200= V+
PUMP Frequency
Duty-Cycle Limit (Note 3)EXT+ or EXT-
Positive Current-Limit ThresholdCSL+ = 0V, FB+ = open circuit
(CSH+ to CSL+)
Negative Current-Limit ThresholdCSH- = V+, FB- = open circuit
(CSH- to CSL-)

MINTYPMAXUNITS
0.010.05%/%
30100mV
3Am013.84.2V
2.0V0.2V170200230kHz
75100125
f
OSC
/2kHz
0958%150225300mV
150225300mV

2_______________________________________________________________________________________

Switch-Mode Regulator with
+5V to ±12V or ±15V Dual Output
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 2, V+ = 5V, 100/200= 12/15= 0V; T
A
= T
MIN
to T
MAX
, unless otherwise noted.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
Output Voltage HighV
OH
EXT+, EXT-, I
L
= 1mA, V+ = 4.5V, PDRV= -3V4.3V
Output Voltage LowV
OL
EXT+, EXT-, I
L
= -1mA, V+ = 4.5V, PDRV= -3V-2.8V
Output Sink CurrentTV+ == +4.255V°,C PDRV = -3V,EXT+ = 4.5V100200mA
A
EXT- = 4.5V200350
Output Source CurrentTV+ == +4.255V°,C PDRV = -3V,EXT+ = 0V-200-100mA
A
EXT- = -3V-350-200
EXT+, C
LOAD
= 2nF70
Output Rise/Fall TimeEXT-, C
LOAD
= 4nF, PDRV = -3V100ns
PUMP Output Voltage (Note 4)V+ = 4.5V, I
L
= -5mA, T
A
= +25°C-3V
Compensation Pin ImpedanceCC+, CC-10k
½
Thermal-Shutdown Threshold190°C
Soft-Start Source CurrentSS = 0V37µA
Soft-Start Sink CurrentV+ = 3.8V, SS = 2V-2-0.5mA
Note 1:
TDheev icaebisli tayr teo 1d0r0iv%e tleosatdesd utpo ttoh e1sAe ilsi mgitusa ruanndteere d0 mbyA ttho e1 c0u0rrmeAn ta-linmd itt ot h1r2e5shmoAld c, oonutdiptiuot nssw iunsign, ga nadu ttohme aotiuct pteuts t ceuqrrueinptment.
source/sink tests. See Figures 2 and 3.
Note 2:
Actual load capability of the circuit of Figure 2 is ±200mA in ±15V mode and ±250mA in ±12V mode. Load regulation is
Note 3:
tGeustaerad natte leodw bery lidmeistisg dn.ue to test equipment limitations.
Note 4:
Measured at Point A, circuit of Figure 2, with PDRV disconnected.

_______________________________________________________________________________________3

Switch-Mode Regulator with
+5V to ±12V or ±15V Dual Output
__________________________________________Typical Operating Characteristics
(Circuit of Figure 2, V+ = 5V, T
A
= +25°C, unless otherwise noted.)
UNDERVOLTAGE LOCKOUT HYSTERESISCHARGE-PUMP LOAD REGULATIONPDRV CURRENT vs. C
EXT-
25-5.06
2±0105kVH zM OMDOED, EMEASURED AT POINT APPUDRMVP FDOIRSCCEODN NTEO C-T4EV D
20-4.55
415-4.0V+ = 5V200kHz
310-3.5
2LOCKOUT
5ENABLED-3.0V+ = 4.5V100kHz
1 -2.5
0123456012345678910 01234
SUPPLY VOLTAGE (V)CHARGE-PUMP LOAD CURRENT (mA)CAPACITANCE AT EXT- (nF)
EFFICIENCY vs. LOAD CURRENT, EFFICIENCY vs. LOAD CURRENT, EFFICIENCY vs. LOAD CURRENT,
22W CIRCUIT, ±15V MODE6W CIRCUIT, ±15V MODE6W CIRCUIT, ±12V MODE
9090100kHz90100kHz
100kHz
8080200kHz80200kHz
200kHz
707070
ICNIRDCUUCITT OORFS F=I GGUORWE A3N, DA 121-AT2502
60 (MPP CORE), 6060
Q2 = TWO IRF9Z30 IN PARALLEL I N D U C T O R S = (GMOPWP ACNODRAE )050-AT1003 I N D U C T O R S = (GMOPWP ACNODRAE )050-AT1003
±15V MODE
50 50 50
0±200±400±600±800±10000±50±100±150±200±2500±75±150±225±300
LOAD CURRENT (mA)LOAD CURRENT (mA)LOAD CURRENT (mA)
PEAK INDUCTOR CURRENT vs. CURRENT-LIMIT THRESHOLD vs.
LOAD CURRENTSOFT-START VOLTAGE
1200100kHz
00111000200
900200kHz
800150
007006500100
004003200MEASURED AT LX-, 50
100±15V MODE
050100150