Rainbow Electronics MAX1847 - Manual

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
♦ 90% Efficiency
♦ +3.0V to +16.5V Input Range
♦ -2V to -200V Output
♦ Drives High-Side P-Channel MOSFET
♦ 100kHz to 500kHz Switching Frequency
♦ Current-Mode, PWM Control
♦ Internal Soft-Start
♦ Electrolytic or Ceramic Output Capacitor
♦ 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 0; 8/01
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Ordering Information
PART TEMP. RANGE PIN-PACKAGE
MAX1846EUB -40 °C to +85°C 10 µMAX
MAX1847EEE -40 °C to +85°C 16 QSOP
Pin Configurations appear at end of data sheet.