MIC9131 Datasheet, PDF (1/20 Pages) Micrel Semiconductor – High-Voltage, High-Speed Telecom DC-to-DC Controller

MIC9131
Micrel
MIC9131
High-Voltage, High-Speed Telecom DC-to-DC Controller
Final Information
General Description
Features
The MIC9131 is a current-mode PWM controller that effi- • Input voltages up to 180V
ciently converts –48V telecom voltages to logic levels. The • Internal oscillator capable of > 2.5MHz operation
MIC9131 features a high voltage start-up circuit that allows • Accurate 75% maximum duty cycle
the device to be connected to input voltages as high as 180V. • Synchronisation capability to 6MHz
The high input voltage capability protects the MIC9131 from • Current sense delay of 34ns
line transients that are common in telecom systems. The • Minimum pulse width of <25ns
start-up circuitry also saves valuable board space and simpli- • 90% efficiency
fies designs by integrating several external components.
• 1.3mA quiescent current
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
• 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
currents. Its low 1.3mA quiescent current allows high effi- _{• Telecom power supplies}
ciency even at light loads.
• Line cards
The MIC9131 has a maximum duty cycle of 75%. For designs • ISDN network terminators
requiring a maximum duty cycle of 50%, refer to the MIC9130. • Micro- and pico-cell base stations
The MIC9131 is available in a 16-pin SOP and 16-pin QSOP • Low power (< 100W) dc-dc converters
package options. The junction temperature range is from • DSL line cards
–40°C to +125°C.
Ordering Information
Part Number
MIC9131BM
MIC9131BQS
Max. Duty Cycle
75%
75%
Junction Temp. Range
–40°C to +125°C
–40°C to +125°C
Package
16-Pin SOP
16-Pin QSOP
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 SYNC AGND 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. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com
July 2001
1
MIC9131