SI9177BM-TI [VISHAY]
200-mA PSM Step Down Converter with Bypass Capability; 200 - mA的PSM降压转换器，具有Bypass功能
| 型号： | SI9177BM-TI |
| 厂家： | 
VISHAY |
| 描述： | 200-mA PSM Step Down Converter with Bypass Capability |
| 文件： | 总9页 (文件大小：96K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Si9177
Vishay Siliconix
New Product
200-mA PSM Step Down Converter with Bypass Capability
APPLICATIONS
FEATURES
ꢀ 2.7-V to 6-V Input Voltage Range
ꢀ 1.2-V to 5-V Output
ꢀ Efficiency of 95% for VOUT of 3.3 V @ 200-mA Load
ꢀ Selectable Pulse Skipping Modulation (PSM) or
Bypass Mode (BP) Operation
ꢀ Cellular Phones, Cordless Phones
ꢀ Computer Point of Use, Notebook
ꢀ PDAs
ꢀ Battery Powered Devices
ꢀ MP3 Players
ꢀ
1
5
0
-
m
W
B
y
p
a
s
s
S
w
i
t
c
h
f
o
r
8
0
0
-
m
A
L
o
a
d
s
ꢀ Integrated MOSFET with Low External Part Count
ꢀ Shutdown Current <1 mA
ꢀ Integrated UVLO and Power on Reset
ꢀ Integrated Soft-Start
ꢀ Over Temperature Protection
ꢀ MLP33-10 or MSOP-10 Packages
DESCRIPTION
The Si9177 is a dual-mode power adjustable output converter.
When it is set to PSM mode, the Si9177 operates as a
pulse-skipping-modulation controlled step-down (buck)
converter with an output voltage range of 1.2 V to 5 V. It has an
integrated MOSFET, capable of supplying 200-mA load
current with a 1.5-mH inductor. The output voltage is adjusted
by a resistive divider on the FB pin. The typical conversion
efficiency is above 90%. A logic HIGH at the BP/PSM pin puts
Si9177 in bypass mode. The main PMOS buck switch is forced
to turn on at 100% duty cycle, overriding the FB signal. The
voltage differential between input and output is the resistive
voltage drop on the internal 150-mW PMOS and the inductor.
The Si9177 delivers 800-mA load in bypass mode.
The Si9177 is available in the space saving MLP33-10 and
MSOP-10 packages. In order to satisfy the stringent ambient
temperature requirements, the Si9177 is rated to handle the
industrial temperature range of -25ꢁC to 85ꢁC.
TYPICAL APPLICATION CIRCUIT
10
1
V
V
V
IN
IN
L
L
1.5 mH
X
2
9
V
OUT
IN
X
C
IN
C
OUT
8
GND
R
R
1
SI9177
7
6
3
4
5
F
ENABLE
BP/PSM
B
ON/OFF
BP/PSM
REF
2
C
REF
NC
Document Number: 70312
S-03663—Rev. B, 07-Apr-03
www.vishay.com
1
Si9177
New Product
Vishay Siliconix
ABSOLUTE MAXIMUM RATINGS (T = 25ꢁ C)
A
V
IN
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5 V
Thermal Impedance (Q )
JA
MLP33-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135ꢁC/W
MSOP-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71ꢁC/W
BP/PSM, ENABLE, F
L . . . . . . . . . . . . . . . . . . . . . . . . -0.3 V to V + 0.3 V
X IN
B,
Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55 to 150ꢁC
Operating Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150ꢁC
Notes
a. Device mounted with all leads soldered or welded to PC board.
b. Derate 7.4 mW/ ꢁC above 25ꢁC.
c. Derate 14 mW/ ꢁC above 25ꢁC.
a.
Power Dissipation (Package)
b.
MLP33-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 481 mW
c
MSOP-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 915 mW
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
V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7 V to 6 V
Inductor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 mH
C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Open
REF
IN
C
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mF
IN
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mF
Operating Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . -25 to 85 ꢁC
OUT
SPECIFICATIONS
Test Conditions Unless Specified
Limits
Typb
-40ꢁC to 85ꢁC, V = V , C = 10 mF
IN
DD,
IN
C
= 4.7 mF, L = 2.2 mH, 2.6 V v V v 5.5 V
OUT
IN
Parameter
Symbol
Mina
Maxa
Unit
R
1
= 11.3 kW, R = 20 kW
2
Converter Operation
Input Voltage
V
2.7
800
200
6
V
IN
Maximum Bypass Mode Current
Maximum PSM Mode Current
MOSFET On-resistance
Power Supply Rejection
I
mA
OUT
r
V
IN
w 3.3 V
150
60
300
mW
DS(on)
PSRR
dB
I
= 0
1.175
1.195
1.215
1.215
1.255
1.235
REF
Feedback Voltage
V
FB
V
I
= 0, TA = 25ꢁC
REF
Start-Up
Start-Up Delay Time
Soft Start Time
t
C
REF
= 0.1 mF, See Figure 1
5
ms
DELAY
t
ss
See Figure 1
100
ms
ENABLE, BP/PSM
Logic High
V
1.5
2.2
IH
V
Logic Low
V
0.4
2.5
IL
I
IH
ENABLE, BP/PSM = V
1
1
IN
Input Current
mA
I
IL
ENABLE, BP/PSM = GND
Protection
Under Voltage Lockout
Under Voltage Lockout Hysteresis
Thermal Shutdown
V
2.35
0.1
165
25
UVLO
V
V
HUVLO
T
Temperature rising
SD
ꢁ
C
Thermal Shutdown Hysteresis
T
V
V
= 3.3 V
= 3.3 V
HSD
IN
Supply Current
BP Mode
75
110
250
1
IN
PSM Mode
190
I
IN
mA
Shutdown
V
IN
= 3.3 V, ENABLE = 0 V
Notes
a. The algebraic convention whereby the most negative value is a minimum and the most positive a maximum, is used in this data sheet.
b. Typical values are for DESIGN AID ONLY, not guaranteed or subject to production testing.
c. Guaranteed by design and characterization, not subject to production testing.
Document Number: 70312
S-03663—Rev. B, 07-Apr-03
www.vishay.com
2
Si9177
Vishay Siliconix
New Product
PIN CONFIGURATION
MSOP-10
10
9
1
2
3
V
V
L
L
IN
X
ORDERING INFORMATION
IN
X
Part Number
Temperature Range
Package
8
ENABLE
BP/PSM
NC
GND
Si9177BM-TI
Si9177BH-TI
F
B
4
5
7
6
-25ꢁC to 85ꢁC
Tape and Reel
REF
Top View
Eval Kit
Temperature Range
Board Type
MLP33
Si9177DB
-25ꢁC to 85ꢁC
Surface Mount
L
L
V
X
10
9
IN
V
IN
X
2
3
4
5
GND
F
REF
ENABLE
BP/PSM
NC
8
7
B
6
Top View
PIN DESCRIPTION
Pin No.
Name
Function
1, 2
V
IN
Input voltage source for buck converter, MOSFET driver, and IC control circuits.
3
ENABLE
BP/PSM
NC
Logic high enables the converter. Logic low shuts down the IC and decreases current consumed to <1 mA.
4
5
Logic high = Bypass mode, logic low = PSM mode.
No Connection
6
REF
1.215-V reference.
7
F
Direct output voltage sense feedback
IC ground
B
8
GND
9, 10
L
X
Inductor connection node
TIMING WAVEFORMS
90%
V
OUT
10%
t
t
= Start-Up Delay Time
= Soft-Start Time
DELAY
SS
V
IN
t
t
DELAY
SS
FIGURE 1. Soft-Start Timing
Document Number: 70312
S-03663—Rev. B, 07-Apr-03
www.vishay.com
3
Si9177
New Product
Vishay Siliconix
FUNCTIONAL BLOCK DIAGRAM
V
IN
V
IN
Reference
Generator
UVLO
POR
REF
BP/PSM
BP
L
L
X
PSM/BP
Controller
Driver
PSM
X
ENABLE
V
ADJ
Turn-On
Control
Zero Current
Detect
NC
F
B
Turn off Control
Peak Current
Comparater
0.6 A
GND
APPLICATION CIRCUIT
10
9
1
V
V
V
IN
IN
L
L
X
1.5 mH
C
10 mF
2
IN
V
OUT
IN
X
C
OUT
10 mF
8
R
R
GND
1
SI9177
7
6
3
4
5
F
ENABLE
BP/PSM
B
ON/OFF
BP/PSM
REF
2
C
REF
NC
MLP33-10
Document Number: 70312
S-03663—Rev. B, 07-Apr-03
www.vishay.com
4
Si9177
Vishay Siliconix
New Product
DETAIL OPERATIONAL DESCRIPTION
Start-Up
load. This mode is enabled by setting the BP/PSM pin to a logic
HIGH. In this mode the IC ignores the feedback signal at the
FB pin, forcing the internal p-channel MOSFET to turn on
continuously. The input-to-output voltage differential is
reduced to the voltage drop across the 150-mΩ MOSFET and
the inductor. Si9177 can bypass 800 mA at 95% typical
efficiency or provide nearly the entire input voltage to the load.
Whenever the converter enters BYPASS mode, the p-channel
MOSFET turns on gradually within 40 µs to reduce surge
current to the input capacitor.
When voltage is first applied to the VIN pin, the UVLO circuitry
prevents the internal p-channel MOSFET from turning on.
Once the VIN voltage exceeds the UVLO threshold of 2.4 V,
and with no other shutdown condition detected, an internal
power-on-reset timer is activated to delay the start of switching
if the BP/PSM pin is held a logic LOW level. The amount of
delay is set by the capacitor CREF on the REF pin and the peak
current in the inductor is limited to 600 mA. If the BP/PSM pin
has a logic HIGH applied, then Bypass Mode soft-start is
achieved by gradually turning on the p-channel MOSFET in
40 µs insuring that the output voltage rises smoothly.
Shutdown
Si9177 is designed to conserve as much battery life as
possible by decreasing current consumption during normal
operation, as well as the shutdown mode. With logic LOW level
on the ENABLE pin, the current consumption of the IC is
decreases to less than 1 µA by shutting off all circuits. A logic
HIGH enables the controller, allowing start up as described in
the “Start-Up” section above.
Pulse Skipping Mode
Si9177 is designed to operate with light loads. When the
BP/PSM pin is connected to logic LOW level, the Si9177
operates in pulse-skipping mode. PSM enhances efficiency in
light load conditions when compared to fixed frequency PWM
mode because switch conduction losses, gate charge and
switching losses are reduced. By delivering energy to the load
only when needed, the p-channel MOSFET gate capacitance
is charged and discharged less frequently and MOSFET
conduction loss is minimized thereby reducing total losses and
increasing converter efficiency. In PSM, the switching
frequency, fSW, increases as and decreases as the load
current increases and decreases. The typical conversion
efficiency in PSM mode is 90%.
Reference and Power-On-Reset Timer
The reference voltage of Si9177 is set to 1.215 V. It is internally
connected to the non-inverting input of the error amplifier. The
power on reset delay time is set by the capacitance on the REF
pin and can be determined from the following relationship:
4
t
4 10 C
PORDELAY =
REF
By operating as a constant on-time converter, the Si9177
achieves PSM operation. The p-channel MOSFET switching
transistor is turned on to deliver energy to the load. The switch
remains on for the minimum on-time or until the inductor
current reaches 600 mA. If the applied on-time is sufficient to
increase the output voltage above the in-regulation set point
(FB pin voltage is greater than VFB), the p-channel MOSFET
turns off for a minimum off-time and continues to apply
constant on-time pulses to insure regulation is maintained. If
the on-time of the p-channel switch causes the output voltage
to rise above the set point, the converter turns off and remains
Output Voltage
The Si9177 is designed with an adjustable output voltage,
VOUT, which is set by resistors R1 and R2, and the feedback
voltage, VFB
.
VOUT is defined according to the following
relationship:
R1
R2
+ ǒ1 ) Ǔ
VOUT
VFB
off until the voltage on FB decreases below VFB
.
where VFB is 1.215 V.
The on-time and minimum off-time are set internally to
minimize ripple voltage at the maximum load current. The
Si9177 has internal compensation reducing the number of
required components and is designed for an inductor value of
1.5 µH and an output capacitor value of 10 µF.
The values of R1 and R2 should be kept between 5 kΩ and
100 kΩ.
Power Switches
BYPASS Mode
The p-channel MOSFET switch is integrated in Si9177 for
optimum performance and minimum overall converter size.
This MOSFET is designed to minimize the gate charge loss as
well as the conduction loss. The typical on-resistance is
150 mΩ with a minimum input voltage of 3.3 V.
Si9177 can also operate in BYPASS mode to handle heavy
load currents or to provide the maximum output voltage to the
Document Number: 70312
S-03663—Rev. B, 07-Apr-03
www.vishay.com
5
Si9177
New Product
Vishay Siliconix
DETAIL OPERATIONAL DESCRIPTION (CONT’D)
An external Schottky diode is required for PSM mode
operation. The Schottky diode handles the freewheeling
inductor current after the p-channel MOSFET is turned off.
speed to improve efficiency. The diode must be connected
from the LX pin to GND.
Over Temperature Protection
The current rating of the Schottky is based on the maximum
load current in PSM mode with the conduction time being the
greatest at maximum input voltage. Combined with the
maximum load current of 200 mA, the Schottky must be able
to conduct 200 mA continuously. Since the forward voltage
drop of the diode, VF, determines the conduction losses, select
the diode with the lowest VF to maximize the converter’s
efficiency. The diode should also be selected for fast switching
Si9177 includes an over temperature protection circuit to
prevent thermal runaway in the MOSFET switch. If the junction
temperature reaches 165ꢁC, an internal soft-start capacitor is
discharged, shutting down the output stage. The converter
remains disabled until the junction temperature falls below
140ꢁC, allowing the converter to resume operation.
TYPICAL CHARACTERISTICS (25ꢁ C UNLESS NOTED)
Supply Current vs. Input Voltage
r
vs. Input Voltage
DS(on)
180
240
220
200
180
160
140
120
100
160
PSM Mode
85 ꢁC
140
120
100
25 ꢁC
-25 ꢁC
80
BP Mode
60
2
3
4
5
6
7
2
3
4
5
6
7
Voltage (V)
Voltage (V)
Efficiency vs. Load Current
Switching Frequency vs. Load Current
100.00
500
450
400
350
300
250
200
150
100
50
V = 3.3 V
OUT
V
IN
= 3.6 V
V
= 3.0 V
= 2.2 V
OUT
95.00
90.00
85.00
80.00
75.00
70.00
V
= 4.0 V
IN
V
OUT
V
IN
= 6.0 V
150
0
0
50
100
150
200
250
0
50
100
200
Current (mA)
Current (mA)
Document Number: 70312
S-03663—Rev. B, 07-Apr-03
www.vishay.com
6
Si9177
Vishay Siliconix
New Product
TYPICAL WAVEFORMS
Typical Switching Waveforms
Typical Switching Waveforms
V
IN
= 4 V, V
= 2.0 V, I
= 6 mA
V
IN
= 4 V, V
= 2.0 V, I
= 100 mA
OUT
OUT
OUT
OUT
V
OUT
V
OUT
50 mV/div
AC Coupled
50 mV/div
AC Coupled
V
LX
V
LX
2 V/div
2 V/div
I
LX
I
LX
200 mA/div
200 mA/div
2 ms/div.
5 ms/div.
Typical Switching Waveforms
Load Transient
= 4 V, V = 2.0 V
V
IN
= 4 V, V
= 2.0 V, I
= 200 mA
V
IN
OUT
OUT
OUT
V
OUT
50 mV/div
AC Coupled
V
OUT
100 mV/div
AC Coupled
V
LX
2 V/div
I
I
LX
OUT
200 mA/div
100 mA/div
0.5 ms/div.
100 ms/div.
Start-Up
V
IN
= 4 V, V
= 2.0 V, I
= 100 mA
Start-Up from Disable
= 4 V, V = 2.0 V, I = 100 mA
OUT
V
OUT
= V
V
IN
ENABLE
IN
OUT
OUT
V
V
IN
ENABLE
2 V/div
2 V/div
V
OUT
V
OUT
1 V/div
1 V/div
50 ms/div.
50 ms/div.
Document Number: 70312
S-03663—Rev. B, 07-Apr-03
www.vishay.com
7
Si9177
New Product
Vishay Siliconix
TYPICAL WAVEFORMS
Start-Up in Bypass Mode
V
IN
= 4 V, I
= 100 mA
OUT
V , BP = V
ENABLE IN
V
IN
2 V/div
V
OUT
2 V/div
50 ms/div.
Document Number: 70312
S-03663—Rev. B, 07-Apr-03
www.vishay.com
8
This datasheet has been download from:
www.datasheetcatalog.com
Datasheets for electronics components.
相关型号：
©2020 ICPDF网 联系我们和版权申明