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MIC9130 Schematic ( PDF Datasheet ) - Micrel Semiconductor

Teilenummer MIC9130
Beschreibung High-Speed Telecom DC-to-DC Controller
Hersteller Micrel Semiconductor
Logo Micrel Semiconductor Logo 




Gesamt 19 Seiten
MIC9130 Datasheet, Funktion
MIC9130
MIC9130
Micrel, Inc.
High-Voltage, High-Speed Telecom DC-to-DC Controller
General Description
The MIC9130 is a current-mode PWM controller that efciently
converts –48V telecom voltages to logic levels. The MIC9130
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 MIC9130 from line transients
that are common in telecom systems. The start-up circuitry
also saves valuable board space and simplies designs by
integrating several external components.
The MIC9130 is capable of high speed operation. Typically
the MIC9130 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 MIC9130 is made safe by
the very fast, 34ns response from current sense to output,
minimizing power dissipation in a fault condition.
The MIC9130 allows for the designs of high efciency power
supplies. It can achieve efciencies over 90% at high output
currents. Its low 1.3mAquiescent current allows high efciency
even at light loads.
The MIC9130 has a maximum duty cycle of 50%. For de-
signs requiring a high duty cycle, refer to the MIC9131. The
MIC9130 is available in a 16-pin SOP and 16-pin QSOP
package options. The rated junction temperature range is
from –40°C to +125°C.
Features
• Input voltages up to 180V
• Internal oscillator capable of >2.5MHz operation
• Synchronisation capability to 4MHz
• Current sense delay of 34ns
• Minimum pulse width <25ns
• 90% efciency
• 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 (< 30W) dc-dc converters
Typical Application
VIN
36V to 72V
MBR0540
12V
40V/0.5A
20Ω
N=5
1μF
16V
T1
1M 0.1μF
38.3k
13 1 2 10
N = 20
N=4
Si4800DY
Si4884DY
B330
2.5μH
330μF (x2)
6.3V
20k 7 FB
6 COMP
1.21k 5 SYNC
332k
0.1μF
8 CPWR
3 RBIAS
12 SS
9 VBIAS
OSC
4
MIC9130
OUT 16
FQD10N20
0.2Ω
200V
ComSpleonpseation
ISNS 14
AGND PGND
11 15
332k
0.2Ω
1W
10nF
4.75k
47pF
OPTO
FEEDBACK
1.5MHz DSL Power Supply
VOUT
3.3V @ 4A
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
November 2008
1
M9999-111108






MIC9130 Datasheet, Funktion
MIC9130
5.010
VBIAS vs. VCC
5.008 RB IAS= 560K
5.006
5.004
5.002
5.000
4.998
4.996
4.994
4.992
4.990 8 9 10 11 12 13 14 15 16 17 18
VCC (V)
VCC Turn On/Off Thresholds
vs. Temperature
7.8
7.6
VC C=10V
RB IAS=560K
Vcc G LO On
7.4
7.2
7
6.8 Vcc G LO Off
6.6
6.-440 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
2
1.95
1.9
1.85
1.8
1.75
1.7
1.65
1.6
1.55
1.58
Enable Threshold
vs. VCC
9 10 11 12 13 14 15 16 17 18
VCC (V)
Peak Short Circuit Depletion
80 FET Current vs. VLINE
75 VC C = 0V
70
65
60 –40°C
55 25°C
50
45 125°C
400 40 80 120 160 200
VLINE (V)
M9999-111108
5V VBIAS Voltage
vs. Temperature
5.06
5.04
5.02
5
4.98
VC C = 10V
RB IAS= 560K
4.96
Rt = 9.47K
4.94
Ct = 470pF
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
ISNS Current Limit Threshold
822.0
821.5
vs. VCC Voltage
RB IAS=560K
821.0
820.5
820.0
819.5
819.0
818.5
818.08 9 10 11 12 13 14 15 16 17 18
VCC (V)
Gate Drive Current
2.5 vs. VCC
2.3
2.1 S I NK
1.9
1.7
1.5
1.3
1.1
0.9 S OURC E
0.7
0.58 9 10 11 12 13 14 15 16 17 18
VCC (V)
Depletion FET Current
12 vs. VLINE
25°C
–40°C
10
8
VC C=7.5V
6
125°C
4
2
00 40 80 120 160
VLINE (V)
6
Micrel, Inc.
5
4.99
4.98
4.97
4.96
4.95
4.94
0
Bias Voltage Load
Regulation
VC C = 10V
1234
IBIAS (mA)
5
ISNS Current Limit Threshold
vs. Temperature
840
VC C= 10V
835 RB IAS= 560K
830
825
820
81-540
0 40 80 120 160
TEMPERATURE (°C)
Peak Short Circuit Depletion
FET Current vs. Temperature
80
75 180V Line
VC C = 0V
70
65
60
55 48V Line
50
45
4-040 0
40 80 120 160
TEMPERATURE (°C)
Depletion FET Current
vs. Low VLINE Voltage
10
9 –40°C
8 25°C
7 125°C
6
5
4
3
2
1
07 7.5 8 8.5 9 9.5 10
VLINE (V)
November 2008

6 Page









MIC9130 pdf, datenblatt
MIC9130
TP_OSCILLATOR= tCHARGE + t DISCHARGE + tDELAY
Where tDELAY= 75ns
fS _
OSCILLATOR
=
TP _
1
OSCILLATOR
fS _ OUTPU
=
1
4
× fS _OSCILLATOR
The timing capacitor, COSC, should be an NPO ceramic or a
temperature stable lm capacitor. Care must be taken when
using capacitor values less than 47pF. The high impedance of
a small value capacitor makes the OSC pin more susceptible
to switching noise. Also, the input capacitance of the OSC pin
and the stray capacitance of the board will have a noticeable
effect on the oscillator frequency.
SYNC 5
VBIAS 9
ROSC OSC 4
3V
COSC
11
AGND
75ns
1-shot
VOSC
1μF
2N3904
4.7μF
ROSC
1.6k
COSC
33pF
VCC 2
SYNC 5
VBIAS 9
4.7μF
OSC 4
AGND 11
3V
Micrel, Inc.
75ns
1-shot
Figure 5b
Oscillator Synchronization
The switching frequency of the MIC9130 can be synchronized
to an external oscillator or frequency source. Figure 6 shows
the relationship between the sync input, oscillator waveform
and gate drive output. The external frequency should be set
at least 15% greater than the free running oscillator frequency
to account for tolerances in the oscillator circuit and external
components. The positive edge of the sync signal resets the
oscillator. The sync pulse frequency, like the oscillator, is twice
the gate drive frequency. When an external sync signal is
applied, the peak amplitude of the oscillator signal (pin 4) is
less than when it is free running because the oscillator signal
is terminated before it reaches its 3V (typical) amplitude.
When not used, the sync pin should be connected to ground
to prevent noise from erroneously resetting the oscillator.
Gate Drive
(pin 16)
tON
tPERIOD
Figure 5a
Higher Switching Frequencies
The MIC9130 is capable of very high switching frequencies.
One of the limitations on the maximum frequency is the cur-
rent capability of the 5V regulator supplying the oscillator
and VBIAS. By powering VBIAS with an external source, e.g.
linear regulator much higher switching frequencies can be
achieved. A simple way of using an external current source
is to set an NPN as an emitter follower. Figure 5b shows the
MIC9130 oscillator frequency set to 4MHz using an external
NPN. The emitter followerj circuit allows the current to be
supplied by VCC while the voltage is regulated to a diode
drop below VBIAS. This conguration is quite stable over
temperature and voltage variations.
TIME (500ns/div)
Figure 6. Sync Waveform
Soft Start Circuit
The soft start is programmed by a capacitor on the soft start
pin. A 4μA current source charges up the capacitor. At power
up, the SS pin is discharged. Once the UVLO and enable
functions release the soft start circuit, the voltage of the ca-
pacitor increases. The active voltage range of the soft start
pin is from typically from 0.9V to 1.7V. The internal current
source increases the voltage on the soft start capacitor to
approximately 4V. The soft start pin and the current sense
voltage are connected to a comparator in tç
PMIC9130. The voltage from the soft start pin effectively
limits the peak current through the current sense resistor by
prematurely terminating the on-time of the gate drive output.
Referring to Figure 1, with the soft start voltage low, the duty
cycle of the output is at a minimum. As the soft start voltage
increases, the duty cycle of the gate drive output increases
M9999-111108
12 November 2008

12 Page





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