MAX1846 Datasheet, PDF (1/20 Pages) Maxim Integrated Products – High-Efficiency, Current-Mode, Inverting PWM Controller

19-2091; Rev 0; 8/01
High-Efficiency, Current-Mode,
Inverting PWM Controller
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 -2V to -200V
output. To minimize switching noise, both devices fea-
ture 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, compati-
bility 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
Features
o 90% Efficiency
o +3.0V to +16.5V Input Range
o -2V 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
PART
MAX1846EUB
MAX1847EEE
Ordering Information
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
10 µMAX
16 QSOP
Typical Operating Circuit
POSITIVE
V_IN
VL
IN
EXT
MAX1846
MAX1847
COMP
CS
FREQ
PGND
P
NEGATIVE
V_OUT
REF
GND
FB
Pin Configurations appear at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
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