MIC9131_06 Datasheet, PDF (1/19 Pages) Micrel Semiconductor – High-Voltage, High-Speed Telecom

MIC9131
MIC9131
Micrel, Inc.
High-Voltage, High-Speed Telecom
DC-to-DC Controller
General Description
The MIC9131 is a current-mode PWM controller that efficiently
converts –48V telecom voltages to logic levels. The MIC9131
features a high voltage start-up circuit that allows the device to
be connected to input voltages as high as 180V. The high input
voltage capability protects the MIC9131 from line transients
that are common in telecom systems. The start-up circuitry
also saves valuable board space and simplifies designs by
integrating several external components.
The MIC9131 is capable of high speed operation. Typically
the MIC9131 can control a sub-25ns pulse width on the gate
out pin. Its internal oscillator can operate over 2.5MHz, with
even higher frequencies available through synchronisation.
The high speed operation of the MIC9131 is made safe by
the very fast, 34ns response from current sense to output,
minimizing power dissipation in a fault condition.
The MIC9131 allows for the designs of high efficiency power
supplies. It can achieve efficiencies over 90% at high output
currents. Its low 1.3mA quiescent current allows high efficiency
even at light loads.
The MIC9131 has a maximum duty cycle of 75%. For designs
requiring a maximum duty cycle of 50%, refer to the MIC9130.
The MIC9131 is available in a 16-pin SOP and 16-pin QSOP
package options. The junction temperature range is from
–40°C to +125°C.
Features
• Input voltages up to 180V
• Internal oscillator capable of > 2.5MHz operation
• Accurate 75% maximum duty cycle
• Synchronisation capability to 6MHz
• Current sense delay of 34ns
• Minimum pulse width of <25ns
• 90% efficiency
• 1.3mA quiescent current
• 1µA shutdown current
• Soft-start
• Resistor programmable current sense threshold
• Selectable soft-start retry
• 4Ω sink, 12Ω source output driver
• Programmable under-voltage lockout
• Constant-frequency PWM current-mode control
• 16-pin SOIC and 16-pin QSOP
Applications
• Telecom power supplies
• Line cards
• ISDN network terminators
• Micro- and pico-cell base stations
• Low power (< 100W) dc-dc converters
• DSL line cards
Typical Application
12V
VIN
36V to 72V
1MΩ
0.1µF
37.4kΩ
13
1
2
10
6:1
L = 530µH
10Ω
10µF
25V
1N5818
4:1
Si4884DY�
(x2)
B320A
Si4884DY�
(x2)
1.5µH
100µF
10kΩ
562kΩ
0.1µF
7 _FB
6 _COMP
3 _RBIAS
12 _SS
8 _CPWR
9 _VBIAS
MIC9131
OUT ¹⁶
SLOPE
COMPENSATION
ISNS
14 _8.2kΩ
OSC SYNCAGND PGND
4
5
11
15
10nF
2.61kΩ
270pF
IRFS3IN20D
0.1Ω
1W
OPTO
FEEDBACK
90% Efficient Telecommunications Power Supply
VOUT
3.3V @ 20A
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com
August 2006
1
M9999-080206