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MAX1846EUB+

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20
General Description
MAX1846/MAX1847 high-efficiency PWM inverting con-
trollers allow designers to implement compact, low-
noise, negative-output DC-DC converters for telecom
and networking applications. Both devices operate
from +3V to +16.5V input and generate -500mV to
-200V output. To minimize switching noise, both
devices feature a current-mode, constant-frequency
PWM control scheme. The operating frequency can be
set from 100kHz to 500kHz through a resistor.
The MAX1846 is available in an ultra-compact 10-pin
µMAX
®
package. Operation at high frequency, compat-
ibility with ceramic capacitors, and inverting topology
without transformers allow for a compact design.
Compatibility with electrolytic capacitors and flexibility
to operate down to 100kHz allow users to minimize the
cost of external components. The high-current output
drivers are designed to drive a P-channel MOSFET and
allow the converter to deliver up to 30W.
The MAX1847 features clock synchronization and shut-
down functions. The MAX1847 can also be configured
to operate as an inverting flyback controller with an N-
channel MOSFET and a transformer to deliver up to
70W. The MAX1847 is available in a 16-pin QSOP
package.
Current-mode control simplifies compensation and pro-
vides good transient response. Accurate current-mode
control and over current protection are achieved
through low-side current sensing.
Applications
Cellular Base Stations
Networking Equipment
Optical Networking Equipment
SLIC Supplies
CO DSL Line Driver Supplies
Industrial Power Supplies
Automotive Electronic Power Supplies
Servers
VOIP Supplies
Features
o 90% Efficiency
o +3.0V to +16.5V Input Range
o -500mV to -200V Output
o Drives High-Side P-Channel MOSFET
o 100kHz to 500kHz Switching Frequency
o Current-Mode, PWM Control
o Internal Soft-Start
o Electrolytic or Ceramic Output Capacitor
o The MAX1847 also offers:
Synchronization to External Clock
Shutdown
N-Channel Inverting Flyback Option
MAX1846/MAX1847
High-Efficiency, Current-Mode,
Inverting PWM Controller
________________________________________________________________
Maxim Integrated Products
1
MAX1846
MAX1847
VL IN
COMP
FREQ
REF
GND
FB
PGND
CS
EXT
P
POSITIVE
V
IN
NEGATIVE
V
OUT
Typical Operating Circuit
19-2091; Rev 2; 9/10
EVALUATION KIT
AVAILABLE
Ordering Information
PART TEMP RANGE PIN-PACKAGE
MAX1846EUB -40°C to +85°C 10 µMAX
MAX1846EUB+ -40°C to +85°C 10 µMAX
MAX1847EEE -40°C to +85°C 16 QSOP
MAX1847EEE+ -40°C to +85°C 16 QSOP
Pin Configurations appear at end of data sheet.
+
Denotes a lead(Pb)-free/RoHS-compliant package.
µMAX is a registered trademark of Maxim Integrated Products, Inc.
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim's website at www.maxim-ic.com.
MAX1846/MAX1847
High-Efficiency, Current-Mode,
Inverting PWM Controller
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
SHDN
= V
IN
= +12V, SYNC = GND, PGND = GND, R
FREQ
= 147kΩ ±1%, C
VL
= 0.47µF, C
REF
= 0.1µF, T
A
= 0°C to +85°C, unless
otherwise noted.)
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.
IN, SHDN to GND ...................................................-0.3V to +20V
PGND to GND .......................................................-0.3V to +0.3V
VL to PGND for V
IN
≤ 5.7V...........................-0.3V to (V
IN
+ 0.3V)
VL to PGND for V
IN
> 5.7V .......................................-0.3V to +6V
EXT to PGND ...............................................-0.3V to (V
IN
+ 0.3V)
REF, COMP to GND......................................-0.3V to (VL + 0.3V)
CS, FB, FREQ, POL, SYNC to GND .........................-0.3V to +6V
Continuous Power Dissipation (T
A
= +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW
16-Pin QSOP (derate 8.3mW/°C above +70°C)...........696mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow)
Lead(Pb)-free...............................................................+260°C
Containing lead(Pb) .....................................................+240°C
PARAMETER CONDITIONS MIN TYP MAX UNITS
PWM CONTROLLER
Operating Input Voltage Range 3.0 16.5 V
V
IN
rising 2.8 2.95
UVLO Threshold
V
IN
falling 2.6 2.74
V
UVLO Hysteresis 60 mV
FB Threshold No load -12 0 12 mV
FB Input Current V
FB
= -0.1V -50 -6 50 nA
Load Regulation
C
COMP
= 0.068µF, V
OUT
= -48V,
I
OUT
= 20mA to 200mA (Note 1)
-1 0 %
Line Regulation
C
COMP
= 0.068µF, V
OUT
= -48V,
V
IN
= +8V to +16.5V, I
OUT
= 100mA
0.04 %
Current-Limit Threshold 85 100 115 mV
CS Input Current CS = GND 10 20 µA
Supply Current V
FB
= -0.1V, V
IN
= +3.0V to +16.5V 0.75 1.2 mA
Shutdown Supply Current
SHDN = GND, V
IN
= +3.0V to +16.5V
10 25 µA
REFERENCE AND VL REGULATOR
REF Output Voltage I
REF
= 50µA 1.236 1.25 1.264 V
REF Load Regulation I
REF
= 0 to 500µA -2 -15 mV
VL Output Voltage I
VL
= 100µA 3.85 4.25 4.65 V
VL Load Regulation I
VL
= 0.1mA to 2.0mA -20 -60 mV
MAX1846/MAX1847
High-Efficiency, Current-Mode,
Inverting PWM Controller
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
SHDN
= V
IN
= +12V, SYNC = GND, PGND = GND, R
FREQ
= 147kΩ ±1%, C
VL
= 0.47µF, C
REF
= 0.1µF, T
A
= 0°C to +85°C, unless
otherwise noted.)
OSCILLATOR
R
FREQ
= 500kΩ ±1% 90 100 110
R
FREQ
= 147kΩ ±1% 255 300 345 Oscillator Frequency
R
FREQ
= 76.8kΩ ±1% 500
kHz
R
FREQ
= 500kΩ ±1% 93 96 97
R
FREQ
= 147kΩ ±1% 85 88 90
Maximum Duty Cycle
R
FREQ
= 76.8kΩ ±1% 80
%
SYNC Input Signal Duty-Cycle
Range
7 93 %
Minimum SYNC Input Logic-Low
Pulse Width
50 200 ns
SYNC Input Rise/Fall Time (Note 2) 200 ns
SYNC Input Frequency Range 100 550 kHz
DIGITAL INPUTS
POL, SYNC, SHDN Input High
Voltage
2.0 V
POL, SYNC, SHDN Input Low
Voltage
0.45 V
POL, SYNC Input Current POL, SYNC = GND or VL 20 40 µA
V
SHDN
= +5V or GND -12 -4 0
SHDN Input Current
V
SHDN
= +16.5V 1.5 6
µA
SOFT-START
Soft-Start Clock Cycles 1024
Cycles
Soft-Start Levels 64
EXT OUTPUT
EXT Sink/Source Current V
IN
= +5V, V
EXT
forced to +2.5V 1 A
EXT high or low, tested with 100mA load, V
IN
= +5V 2 5
EXT On-Resistance
EXT high or low, tested with 100mA load, V
IN
= +3V 5 10
Ω
Note 1: Production test correlates to operating conditions.
Note 2: Guaranteed by design and characterization.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20

MAX1846EUB+

Mfr. #:
Buy MAX1846EUB+
Manufacturer:
Maxim Integrated
Description:
Switching Controllers Current-Mode Invert PWM Controller
Lifecycle:
New from this manufacturer.
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