SI9121DY-3 [VISHAY]
High-Voltage, Non-Isolated Buck-Boost Converter for ISDN Digital Phones; 高压，非隔离降压 - 升压型转换器，用于ISDN数字话机
| 型号： | SI9121DY-3 |
| 厂家： | 
VISHAY |
| 描述： | High-Voltage, Non-Isolated Buck-Boost Converter for ISDN Digital Phones |
| 文件： | 总9页 (文件大小：98K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Si9121
Vishay Siliconix
High-Voltage, Non-Isolated Buck-Boost Converter
for ISDN Digital Phones
FEATURES
D Fixed +5-V or +3.3-V Output
D −10-V to −60-V Input Voltage Range
D 95-kHz PWM Operation
D Current Mode Control
D Integrated Floating Feedback Amplifier
D Hiccup Mode Short Circuit
Protection
D On-Chip 70-V, 1.5-W N-Channel
D Integrated Soft-Start and Oscillator
D High Efficiency Over Full Load Range
MOSFET Switch
D Thermal Shutdown
D Integrated High Voltage Start-Up Circuit,
D SOIC-8 Narrow-Body Package
D Under Voltage Lockout
with VCC Regulator
DESCRIPTION
The Si9121 simplifies the −48-V to +5-V or +3.3-V converter
design for ISDN application by integrating the floating
feedback error amplifier providing direct output voltage
regulation. This approach eliminates the need for an external
shunt regulator. The Si9121 also integrates a high voltage
depletion mode MOSFET which allows the converter to be
powered directly from the high input bus voltage without
requiring an external start-up circuit. Combined with simple
magnetic design due to its non-isolated topology, the Si9121
provides a one-chip solution for complete ISDN power supply.
In order to reduce external component count, the Si9121 has
a fully integrated 95-kHz oscillator and soft-start circuit.
The Si9121 is available in both standard and lead (Pb)-free
SOIC-8 pin packages, and is offered in either +5-V or +3.3-V
fixed output options (Si9121DY-5 or Si9121DY-3,
respectively). In order to satisfy the stringent ambient
temperature requirements in many applications, the Si9121 is
rated to the industrial temperature range of −40_C to 85_C.
FUNCTIONAL BLOCK DIAGRAM
GND
V
CC
Regulator
V
CC
Reference Generator
V
OUT
BYPASS
V
OUT
L
X
+5 V/400 mA
or
+3.3 V/400 mA
Control
COMP
V
NEG
C
S
V
NEG
−48 V
Document Number: 71112
S-40708—Rev. C, 19-Apr-04
www.vishay.com
1
Si9121
Vishay Siliconix
ABSOLUTE MAXIMUM RATINGS (ALL VOLTAGES REFERENCED TO GND = 0 V)
V
V
V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −63 V
Operating Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150_C
NEG
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V
−0.3 V to V + 0.3 V
CC
a
CS
CC
NEG
Power Dissipation (Package)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V
+ 13.2 V
b
NEG
8-Pin SOIC (Y Suffix) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.25 W
I
(peak current ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 A
LX
a
Thermal Impedance (Q
)
JA
V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V
OUT
8-Pin SOIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 _C/W
Bypass, CS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
V −0.3 V to V +0.3 V
NEG CC
Notes
(V − V ) internal power MOSFET . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 V
Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −65 to 150_C
LX
CS
a. Device mounted with all leads soldered or welded to PC board.
b. Derate 10 mW/_C above 25_C.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation
of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
RECOMMENDED OPERATING RANGE (ALL VOLTAGES REFERENCED TO GND = 0 V)
V
V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −10 V to −60 V
V
(externally supplied) . . . . . . . . . . . . . . . . V
+ 9.5 V to V
+ 12.0 V
NEG
CC
NEG
NEG
(internally regulated) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V
+ 8.5 V
Digital Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V to V
CC
CC
NEG
RECOMMENDED EXTERNAL COMPONENTS ( SEE TYPICAL APPLICATIONS CIRCUIT )
L = 68 mH, C
= 220 mF // 0.1 mF, CIN = 33 mF, C
= 0.1 mF, C
= 1 mF, R
= 0.25 W, 0.5 W
OUT
BYPASS
VCC
SENSE
a
SPECIFICATIONS (All Voltages Are With Respect To V
Unless Otherwise Specified)
NEG
Limits
Test Conditions (Internally Regulated)
Unless Otherwise Specified
−40 to 85_C
Typd
Parameter
Symbol
Tempb Minc
Maxc
Unit
V
NEG
= −10 to −60 V
Output Voltage (with respect to GND = 0 V)
+5-V Converter
Full
Full
4.80
3.17
5.00
3.30
5.20
3.43
V
OUT
10 mA <I
< 250 mA
V
LOAD
+3.3-V Converter
Line Regulation (with respect to GND = 0 V)
Line Regulation
−60 V v V
v −40 V
Full
Full
1
%
V
NEG
VCC (Internal Regulator)
V
CC
Bias Voltage
V
CC
7.5
6.6
8.5
9.5
UVLO
V
−
CC
Under Voltage Lockout
Turn-On
Full
7.6
0.6
8.7
V
NEG
V
Hysteresis
DV
Room
Soft-Start
Error Amplifier Start-Up Current
Oscillator
I
V
= 0 V
Room
Room
10
95
mA
SS
OUT
Switching Frequency
f
80
10
110
20
kHz
OSC
Error Amplifier
Transconductance
gm
Room
Room
15
umho
V
Internal Error Amplifier
Output Clamp Voltage
Clamp Voltage
V
3.5
CL
Current Limit
Threshold Voltage
MOSFET Switch
N-Channel MOSFET
V
Full
0.57
0.67
1.5
0.77
2.5
V
CS
r
Room
W
DS(on)
Document Number: 71112
S-40708—Rev. C, 19-Apr-04
www.vishay.com
2
Si9121
Vishay Siliconix
a
SPECIFICATIONS (All Voltages Are With Respect To V
Unless Otherwise Specified)
NEG
Limits
Test Conditions (Internally Regulated)
Unless Otherwise Specified
−40 to 85_C
Typd
Parameter
Symbol
Tempb Minc
Maxc
Unit
V
NEG
= −10 to −60 V
Supply
Supply Current
I
GND to V
Full
Full
1.2
1.5
1.5
2.0
GND
NEG
(Internally Regulater)
Supply Current
I
V
CC
to V
+10 V; V
>−20 V
CC
NEG
NEG
mA
(External V Applied)
CC
V
supply Current
I
V
to V
NEG
Full
Full
0.2
5
0.3
30
OUT
OUT
OUT
Start-Up Current
I
V
= 0 V
START
CC
Thermal Shutdown
Thermal Shutdown Temperature
Thermal Hysteresis
T
T
170
25
OTP
_C
HYS
Efficiency
+5 V
Room
Room
77
73
Efficiency
400-mA Output, V
= −48 V
%
NEG
+3.3 V
Notes
a. Refer to PROCESS OPTION FLOWCHART for additional information.
b. Room = 25_C, Full = as determined by the operating temperature suffix.
c. The algebraic convention whereby the most negative value is a minimum and the most positive a maximum.
d. Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing.
DETAILED BLOCK DIAGRAM
4
5
COMP
V
OUT
10 mA
2 mA
R1*
R2*
V
V
NEG
CC
Soft Start
+
−
−
H
L
GM
3.5 V
1.5 V
+
Hiccup Discharge Mode
−
V
+
−
REF
1.25 V
+
6
7
GND
OSC
OTP
V
CC
8
0.6 V
L
X
50% Max.
Duty Cycle
PWM
OCL
−
−
Low Side
Error Amp
+
−V
IN
R
S
Q
Bias/
Reference
Circuit
3
BYPASS
+
−
0.67 V
1
CS
−
+
−
0.6-V Hysteresis
+
+
*R1 and R2 are internal voltage setting resistors used to set
output voltage to fixed 3.3 V or 5 V.
−
2
8.5 V
V
NEG
Document Number: 71112
S-40708—Rev. C, 19-Apr-04
www.vishay.com
3
Si9121
Vishay Siliconix
TYPICAL CHARACTERISTICS (INTERNALLY REGULATED, 25_C UNLESS NOTED)
5-V V
vs. Temperature
3.3-V V
vs. Temperature
OUT
OUT
5.15
5.10
5.05
5.00
4.95
4.90
4.85
3.45
3.40
3.35
3.30
3.25
3.20
3.15
−40
−20
0
20
40
60
80
100
−40
−20
0
20
40
60
80
100
Temperature (_C)
Temperature (_C)
r
vs. Temperature
Frequency vs. Temperature
DS(on)
2.5
2.0
1.5
1.0
0.5
105
100
95
90
85
−40
−20
0
20
40
60
80
100
−40
−20
0
20
40
60
80
100
Temperature (_C)
Temperature (_C)
Supply Current vs. V
NEG
1.4
1.3
1.2
1.1
1.0
25_C
85_C
−40_C
−60
−50
−40
−30
− (V)
−20
−10
V
NEG
Document Number: 71112
S-40708—Rev. C, 19-Apr-04
www.vishay.com
4
Si9121
Vishay Siliconix
TYPICAL CHARACTERISTICS (INTERNALLY REGULATED, 25_C UNLESS NOTED)
Output Load vs. Efficiency (Si9121DY-3)
No V Winding
Output Load vs. Efficiency (Si9121DY-5)
No V Winding
CC
CC
90
80
70
60
50
40
30
20
10
0
90
80
70
60
50
40
30
20
10
0
10 V
IN
V
IN
= 10 V
48 V
IN
60 V
IN
V
IN
= 48 V
V
IN
= 60 V
10
100
(mA)
1000
10
100
1000
I
(mA)
I
OUT
OUT
Output Load vs. Efficiency (Si9121DY-3)
With V Winding
Output Load vs. Efficiency (Si9121DY-5)
With V Winding
CC
CC
90
80
70
60
50
40
30
20
10
0
90
80
70
60
50
40
30
20
10
0
48 V
IN
V
NEG
= −10 V
10 V
IN
60 V
IN
V
NEG
= −48 V
V
NEG
= −60 V
10
100
(mA)
1000
10
100
(mA)
1000
I
OUT
I
OUT
Document Number: 71112
S-40708—Rev. C, 19-Apr-04
www.vishay.com
5
Si9121
Vishay Siliconix
PIN CONFIGURATION AND ORDERING INFORMATION
ORDERING INFORMATION
SOIC-8
Part Number
Temperature Range
Package
Si9121DY-5-T1
CS
L
X
1
2
3
4
8
7
6
5
Si9121DY-5-T1—E3
Si9121DY-3-T1
V
V
CC
NEG
Tape and Reel
Si9121
BYPASS
COMP
GND
−40 to 85C
Si9121DY-3-T1—E3
V
OUT
Si9121DY-5
Si9121DY-3
Bulk
Top View
Eval Kit
Temperature Range
Board Type
Si9121DB-5
Si9121DB-3
Surface Mount and
Thru-Hole
−10 to 70_C
PIN DESCRIPTION
Pin Number
Name
Function
1
2
3
4
5
6
CS
Current sense pin to detect the inductor current for current mode control and over current protection
Negative supply voltage (−10 V to −60 V)
V
NEG
BYPASS
+1.5-V bandgap reference. Decouple with 0.1 mF capacitor.
Compensation node to stabilize the converter
COMP
V
OUT
Output voltage feedback connected to the PWM summing comparator
Low impedance system ground
GND
Internally generated supply voltage for the internal circuit and MOSFET drive circuit. Decouple with an external
bypass capacitor.
7
8
V
CC
L
X
Inductor connection node
DETAILED DESCRIPTION
Start-Up
the UVLO threshold. For the recommended frequency
compensation components (see Typical Application Circuit)
the soft-start time is approximately 10 ms.
The UVLO circuit prevents the internal circuits from turning on
if VCC is less than 7.6 V (typical) above the negative supply
voltage at VNEG pin. With a typical hysteresis of 0.6 V, the
controller is continuously powered on until the VCC voltage
drops below 7.0 V. This hysteresis prevents the converter
from oscillating during the start-up phase and unintentionally
locking up the system. Once (VCC − VNEG) exceeds the UVLO
threshold the internal reference, oscillator, and soft-start
circuits are enabled.
Oscillator
The oscillator is designed to operate at a nominal frequency
of 95 kHz with no external components. The 95-kHz operating
frequency allows the converter to operate in PWM mode
during the full load condition even though the duty cycle is very
low. The 95kHz switching frequency also allows the converter
to operate at optimal efficiency without a large output inductor
and capacitor.
Soft-Start
PWM Mode and Current Limit
The Si9121 has an on-chip soft-start circuit which utilizes the
error amplifier external compensation network to ramp the
output NMOS transistor current limit which, in turn, allows the
output voltage to rise gradually without excessive overshoot.
The soft-start circuit is enable once the VCC voltage exceeds
The Si9121 is a current-mode converter designed to operate
in PWM mode. It features pulse-by-pulse peak current limiting
such that when the peak current sensed voltage on the CS pin
is greater than 0.67 V the switch is turned off for the remainder
of the clock cycle.
Document Number: 71112
S-40708—Rev. C, 19-Apr-04
www.vishay.com
6
Si9121
Vishay Siliconix
DETAILED DESCRIPTION
Bypass
dissipation the regulator’s thermal circuit will continue to pulse
the regulator on and off. This is called thermal cycling.
The bypass voltage of the Si9121 is set at a particular positive
reference relative to the VNEG pin. The bypass voltage is used
to set an accurate voltage and bias current for the on-chip
oscillator and soft-start circuits. The 0.1-mF ceramic
decoupling capacitor is recommended between the bypass
and VNEG. No other components should be connected to this
pin.
Hiccup Mode Short Circuit Protection
In addition to the thermal shutdown and the cycle-by-cycle
current limiting features already described, the Si9121 has a
built-in hiccup mode timer to handle a continuous output
short-circuit and to automatically restart the device when the
short-circuit is removed.
Error Amplifier
If an output short-circuit occurs, the device immediately enters
a cycle-by-cycle current limiting mode. As long as the thermal
shutdown is not activated then the Si9121 automatically
determines whether the internal hiccup timer should be started
by monitoring the COMP pin. If VCOMP exceeds an upper
threshold voltage (approximately 3.5 V) the timer is started
and the external network at the COMP pin is discharged by an
internal 2-mA current sink until VCOMP reaches approximately
1.5 V. (Note: all voltages are with respect to VNEG). At this
point, the circuit reverts to the normal soft-start mode, whereby
the COMP network is charged by its internal soft-start 10-mA
current source and the circuit will attempt to start up in the
normal manner. However, if the output short circuit is still
present, the converter will again enter the cycle-by-cycle
current limiting mode until the COMP pin voltage reaches
3.5 V, whereupon this cycle repeats until the short circuit is
removed.
With a −48-V bus voltage, the converter is referenced to the
−48-V (VNEG) node as its system ground. However, the +5-V
or +3.3-V output is referenced to the GND pin, which is
normally connected to 0 V. To regulate this output voltage, the
Si9121 has an on-chip error amplifier which continuously
monitors the output voltage and compares it to a reference
voltage. This difference signal is level-shifted to the low side
circuit to control the power switch duty-cycle and hence the
regulation of the output voltage. Frequency compensation for
the error amplifier is achieved by connecting an external
network between the COMP pin and the VNEG pin.
VCC Regulator
VCC is an internally generated bias supply voltage which
should be externally bypassed with a 0.1-mF capacitor
connected to the negative supply voltage, VNEG. No load
current should be drawn from the VCC pin. VCC may be
supplied from an external source of 9.5-V to 12-V referenced
to VNEG. In this configuration, the internal VCC regulator is
The duty cycle imposed by the hiccup timer allows the Si9121
to handle continuous short-circuit without damage as long as
the recommended component values shown in the Typical
Application Circuit are used.
disabled when the VCC receives 9.5-V, or greater, above VNEG
.
Thermal Shutdown
MOSFET Switch
The Si9121 also includes thermal shutdown which shuts down
the device when junction temperature exceeds 170_C due to
over heating. In thermal shutdown once the die temperature
cools to below 145_C the regulator is enabled. If the die
temperature is excessive due to high package power
The low-side n-channel MOSFET switch is integrated to
provide optimum performance and to minimize the overall
converter size. The typical 1.5-W rDS(on) of the MOSFET
allows the converter to deliver up to 2 W of output power.
Document Number: 71112
S-40708—Rev. C, 19-Apr-04
www.vishay.com
7
Si9121
Vishay Siliconix
TYPICAL APPLICATION CIRCUIT
GND
L1
68 mH
220 mF
C2
0.1 mF*
C3
+
V
OUT
6
3
7
2
8
5
4
1
+5 V/400 mA
or
GND
L
X
10MQ100N
+3.3 V/400 mA
BYPASS
V
OUT
V
V
COMP
CS
CC
NEG
R2
+
75 kW
33 mF
80 V
C4
0.1 mF
C5*
0.1 mF
C1
1 mF
C6
180 pF
C7
(27 kW for Si9121DY-3)
R1
Si9121DY-5
0.25 W
or
+
1
/
2
W
0.1 mF
Si9121DY-3
C8
V
NEG
−10 to −60 V
*Optional
FIGURE 1. Typical Applications Circuit
Silk Screen
T1
GND
GND
68 mH
Np
Ns
C7
220 mF
10 V
+
C8*
C1
33 mF
80 V
0.1 mF
+
C2*
0.1 mF
D2
BAS21
D1
+V
OUT
10MQ100N
1
2
3
4
8
7
6
5
CS
COIL
V
NEG
V
CC
+5 V
@ 400 mA
BYPASS
COMP
GND
V
OUT
C5
0.1 mF
R1
0.25
C6
1 mF
Si9121DY-5
C3
0.1 mF
C4
180 pF
1
/
2
W
R2
*Optional
75 kW
(27 kW for Si9121DY-3)
−V
IN
−10 to −60 V
FIGURE 2. Si9121 Application with External Vcc Through Winding
Document Number: 71112
S-40708—Rev. C, 19-Apr-04
www.vishay.com
8
Legal Disclaimer Notice
Vishay
Notice
Specifications of the products displayed herein are subject to change without notice. Vishay Intertechnology, Inc.,
or anyone on its behalf, assumes no responsibility or liability for any errors or inaccuracies.
Information contained herein is intended to provide a product description only. No license, express or implied, by
estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Vishay's
terms and conditions of sale for such products, Vishay assumes no liability whatsoever, and disclaims any express
or implied warranty, relating to sale and/or use of Vishay products including liability or warranties relating to fitness
for a particular purpose, merchantability, or infringement of any patent, copyright, or other intellectual property right.
The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications.
Customers using or selling these products for use in such applications do so at their own risk and agree to fully
indemnify Vishay for any damages resulting from such improper use or sale.
Document Number: 91000
Revision: 08-Apr-05
www.vishay.com
1
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