PM6685 [STMICROELECTRONICS]
DUAL STEP-DOWN CONTROLLER WITH AUXILARY VOLTAGES FOR NOTEBOOK SYSTEM POWER; 与辅助的电压，用于笔记本电脑系统电源双路降压型控制器
| 型号： | PM6685 |
| 厂家： | 
ST |
| 描述： | DUAL STEP-DOWN CONTROLLER WITH AUXILARY VOLTAGES FOR NOTEBOOK SYSTEM POWER |
| 文件： | 总16页 (文件大小：892K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PM6685
DUAL STEP-DOWN CONTROLLER WITH AUXILARY VOLTAGES
FOR NOTEBOOK SYSTEM POWER
Preliminary Data
Features
■ CONSTANT ON TIME TOPOLOGY ALLOWS
VERY FAST LOAD TRANSIENTS
■ 6V TO 28V INPUT VOLTAGE RANGE
■ FIXED 5V-3.3V OUTPUT VOLTAGES
■ 5V AND 3.3V ALWAYS VOLTAGES
AVAILABLE DELIVER 100mA PEAK
CURRENT
VFQFPN-32 5X5
■ 1.23V ± ±1% REFERENCE VOLTAGE
AVAILABLE
Description
■ NO R
CURRENT SENSING USING
SENSE
PM6685 is
a
dual step-down controller
LOW SIDE MOSFETs’ R
DS(on)
specifically designed to provide extremely high
efficiency conversion, with lossless current
sensing technique. The constant on-time
architecture assures fast load transient response
and the embedded voltage feed-forward provides
nearly constant switching frequency operation. An
embedded integrator control loop compensates
the DC voltage error due to the output ripple.
Pulse skipping technique increases efficiency at
very light load. Moreover a minimum switching
frequency of 25kHz is selectable to avoid audio
noise issues. The PM6685 provides a selectable
switching frequency, allowing either 200kHz/
300kHz, 300kHz/400Khz or 400kHz/500kHz
operation of the 5V/3.3V switching sections...
■ ACCURATE CURRENT SENSE WITH
R
SENSE
■ NEGATIVE CURRENT LIMIT
■ SOFT START INTERNALLY FIXED AT 2ms
■ SOFT OFF FOR OUTPUT DISCHARGE
■ LATCHED OVP AND UVP
■ SELECTABLE PULSE SKIPPING AT LIGHT
LOADS
■ SELECTABLE MINIMUM FREQUECY
(25kHz) IN PULSE SKIP MODE
■ 4 mW MAXIMUM QUIESCENT POWER
■ INDIPENDENT POWER GOOD SIGNALs
■ OUTPUT VOLTAGE RIPPLE
Applications
COMPENSATION
■ NOTEBOOK COMPUTERS
■ TABLET PC OR SLATES
■ MOBILE SYSTEM POWER SUPPLY
■ 3-4 CELLS Li+ BATTERY POWERED
DEVICES
Order codes
Part number
Marking
Package
Packing
PM6685
PM6685
VFQFPN-32 5X5
TAPE & REEL
Rev 1
1/16
September 2005
This is preliminary information on a new product now in development or undergoing evaluation.
Details are subject to change without notice.
www.st.com
16
PM6685
Contents
1
2
3
4
5
6
7
Typical application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Electrical ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Block & pin connection diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Functional & block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Package Mechanical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2/16
PM6685
1 Typical application circuit
1
Typical application circuit
Figure 1. Circuit
3/16
2 Electrical ratings
PM6685
2
Electrical ratings
Table 1.
Absolute maximum ratings
Parameter
Symbol
Value
Unit
SGND1 to SGND2
Shorted
COMPx, FSEL, LDO3_SEL, VREF, SKIP to SGND1,
SGND2
-0.3 to V + 0.3
V
CC
Enx, SHDN, PGOD_LDO3, OUTx, PGOODx, V to
CC
-0.3 to 6
SGND1, SGND2
LDO3 to SGND1, SGND2
LGATEx to PGND
-0.3 to LDO5 + 0.3
-0.3 to LDO5 + 0.3
-0.3 to 6
V
V
V
V
V
V
V
V
V
W
HGATEx and BOOTx, to PHASEx
PHASEx to PGND
-0.6 to 36
-0.6 to 42
-6 to 0.3
CSENSEx, to PGND
CSENSEx to BOOTx
V5SW, LDO5 to PGND
VIN to PGND
-0.3 to 0.6
-0.3 to 36
-0.3 to 0.3
2
PGND to SGND1, SGND2
Power dissipation at T
= 25°C
amb
Table 2.
Symbol
Thermal data
Description
Value
Unit
Thermal Resistance Junction to ambient (mounted on
demoboard)
R
T
45
°C/W
thJA
Storage temperature range
-40 to 150
-10 to 125
°C
°C
STG
T
Junction operating temperature range
J
4/16
PM6685
3 Block & pin connection diagrams
3
Block & pin connection diagrams
Figure 2. Pin connection diagram (top view)
5/16
3 Block & pin connection diagrams
PM6685
Table 3.
Pin No
Pin description
PM6685
Function
1
2
SGND
Signal ground. Reference for internal logic circuitry.
COMP3
DC voltage error compensation pin for the 3.3V switching section.
Frequency selection pin. It provides a selectable switching frequency, allowing
either 200kHz/300kHz, 300kHz/400kHz or 400kHz/500kz operation of the 5V/
3.3V switching sections.
3
FSEL
EN3
3.3V SMPS enable input. The 3.3V section is enabled appling a high logic level
(>2.4V) to this pin, while is disabled appling a low logic level (<0.8V). When the
section is disabled the High Side gate driver goes low and Low Side gate driver
goes high. If both EN3 and EN5 pins are low and SHDN pin is high the device
enters in standby mode.
4
Shutdown control input. The device enters its shutdown mode with 9µA of supply
current if VSHDN is less than the device off threshold voltage and doesn't restart
until VSHDN is greater than the device on threshold voltage. The SHDN pin can
be connected to Vbatt through a voltage divider to program an undervoltage
lockout. In shutdown mode, the gate drivers of the two switching sections are in
high impedance.
5
6
SHDN
Power Good ouput signal for the 3.3V linear regulator. This pin is an open drain
PGOOD LDO3 output. It is shorted to GND if LDO3_SEL pin is at its low level or if the ouput
voltage on LDO3 pin is lower than 2.6V.
3.3V Linear regulator output. LDO3 can provide 100mA peak current. If
LDO3_SEL pin is connected to VREF and OUT3 is greater than the LDO3
bootstrap switch threshold, the LDO3 regulator shuts down and the LDO3 pin will
7
8
LDO3
be directly connected to OUT3 through a 3 (max) switch.
If LDO3_SEL pin is at its low level the LDO3 is always OFF.
If LDO3_SEL pin is at its high level the LDO3 is always ON.
Output voltage sense for the 3.3V switching section.This pin must be directly
connected to the output voltage of the switching section.
OUT3
Bootstrap capacitor connection for the switching 3.3V section. It supplies the high-
side gate driver.
9
BOOT3
10
11
HGATE3
PHASE3
High-side gate driver ouput for the 3.3V section.
Switch node connection and return path for the high side driver for the 3.3V
section.
Current sense input for the switching 3.3V section. This pin must be connected
through a resistor to the drain of the synchronous rectifier (RDSON sensing) or to
the source of the synchronous rectifier (RSENSE sensing) to set the current limit
threshold.
12
CSENSE3
13
14
15
16
LGATE3
PGND
Low-side gate driver output for the 3.3V section.
Power ground.
LGATE5
SGND2
Low-side gate driver output for the 5V section.
Signal ground for analog circuitry.
Internal 5V regulator bypass connection. When the main 5V ouput voltage is
greater than the boostrap switch threshold, the LDO5 regulator shuts down and
the LDO5 pin will be directly connected to OUT5 through a 3 (max) switch.
17
V5SW
If not used, it must be tied to ground.
6/16
PM6685
3 Block & pin connection diagrams
Table 3.
Pin description
5V internal regulator output. LDO5 pin supplies all gate drivers, the internal
circuitry and an external load. It can provide up to 100mA peak current.
18
LDO5
Device input supply voltage. A bypass filter (4 Ω and 4.7 µF) between the battery
19
20
VIN
and this pin is recommended.
Current sense input for the switching 5V section. This pin must be connected
through a resistor to the drain of the synchronous rectifier (R
sensing) or to
DSON
CSENSE5
the source of the synchronous rectifier (R
threshold.
sensing) to set the current limit
SENSE
21
22
PHASE5
HGATE5
Switch node connection and return path for the high side driver for the 5V section.
High-side gate driver ouput for the 5V section.
Bootstrap capacitor connection for the switching 5V section. It supplies the high-
side gate driver.
23
BOOT5
Pulse skipping mode control input. It is a three states pin.
If the pin is at its high level(e.g. cnnected to LDO5) the PWM mode is enabled.
If the pin is at its low level (e.g. connected to GND), the pulse skip mode is
enabled.
24
SKIP
If the pin is at its middle level (e.g. connected to Vref) the pulse skip mode is
enabled but limiting the min frequency to 25KHz.
5V SMPS enable input. The 5V section is enabled appling a high logic level
(>2.4V) to this pin, while is disabled appling a low logic level (<0.8V). When the
section is disabled the High Side gate driver goes low and Low Side gate driver
goes high. If both EN3 and EN5 pins are low and SHDN pin is high the device
enters in standby mode.
25
EN5
Power Good ouput signal for the 5V section. This pin is an open drain ouput.
26
27
PGOOD5
PGOOD3
The pin is pulled low if the output is disabled or is out of the specified window
(approximately +/- 10% of its nominal value).
Power Good ouput signal for the 3.3V section. This pin is an open drain ouput.
The pin is pulled low if the output is disabled or is out of the specified window
(approximately +/- 10% of its nominal value).
Control pin for the 3.3V internal linear regulator. This pin determines three
operative modes for the LDO3.
If LDO3_SEL pin is at its low level the LDO3 is always OFF.
If LDO3_SEL pin is at its high level the LDO3 is always ON
28
29
LDP3SEL
If LDO3_SEL pin is connected to VREF and OUT3 is greater than the LDO3
bootstrap switch threshold, the LDO3 regulator shuts down and the LDO3 pin will
be directly connected to OUT3 through a 3 (max) switch.
Output voltage sense for the 5V switching section.This pin must be directly
connected to the output voltage of the switching section.
OUT5
30
31
COMP5
DC voltage error compensation pin for the 5V switching section.
Device Supply Voltage pin. Connect this pin to LDO5
V
CC
High accuracy output voltage reference (1.237V). It can deliver 50uA. Bypass to
SGND with a 100nF capacitor.
32
VREF
7/16
4 Electrical characteristics
PM6685
4
Electrical characteristics
(V = 12V; T
= 0°C to 85°C unless otherwise specified)
IN
amb
Table 4.
Simbol
Supply section
Parameter
Test Condition
Min.
6
Typ.
Max.
Unit
V
V
=V , LDO5 in regulation
Input voltage range
28
5.5
4.9
V
IN
out
ref
V
IC supply voltage
4.5
V
V
CC
Turn-on voltage threshold
Turn-off voltage threshold
Hysteresis
4.8
4.75
50
V
4.6
V
V5SW
mV
V
V
Maximum operating range
5.5
3
V5SW
LDO5 Internal Bootstrap
Switch Resistance
R
V5SW >4.9V
1.8
1.8
12
Ω
Ω
Ω
DS(on)
LDO3 Internal Bootstrap
Switch Resistance
VOUT3 = 3.3V
3
OUT_ Discharge-Mode
On-resistance
25
R
DS(on)
OUT3, OUT5_ Discharge-Mode
Synchronuos Rectifier
0.2
0.35
0.5
4
V
Turn-on level
VOUT5>5.1V,VOUT3>3.34V
V5SW to 5V
Pin
Operating Power consumption
mW
LDO5, LDO3 no load
V
V
Shutdown Current
Standby Current
Ish
Isb
SHDN connected to GND,
ENx to GND, V5SW to GND
14
18
µA
µA
IN
IN
150
250
Table 5.
Simbol
Shutdown section
Parameter
Test Condition
Min.
Typ.
Max.
Unit
Device ON threshold
Device OFF threshold
0.95
0.8
1.35
0.85
1.6
0.9
V
V
V
SHDN
8/16
PM6685
Table 6.
Simbol
Electrical characteristics (continued)
Parameter
Test Condition
Min.
2
Typ.
Max.
6
Unit
ms
Soft Start Ramp time
Input bias current limit
I
90
-5
100
110
5
µA
CSENSE
V
V
- V
Comparator offset
mV
mV
CSENSE
PGND
PGND
- V
Zero Crossing Comparatot Offset
-5
5
PHASE
PHASE
Fixed Negative current limit
Threshold
V
- V
-120
mV
ns
PGND
OUT5=5V
OUT3=3.3V
OUT5=5V
OUT3=3.3V
OUT5=5V
OUT3=3.3V
2083
917
FSEL to GND
FSEL to VREF
FSEL to LDO5
1390
688
T
ON-Time duration
ON
1040
550
T
Minimum OFF-Time
Voltage Accuracy
Load regulation
300
350
ns
V
OFFMIN
4.2V < V
< 5.5V
1.224 1.237 1.249
LDO5
-100µA < I
< 100µA
-4
4
mV
REF
V
REF
Undervoltage Lockout fault
threshold
Falling edge of REF
0.95
V
COMP
COMP
Over voltage clamp
Under voltage clamp
Line regulation
250
mV
-150
Both SMPS, 6V< V <28V
0.004 %/V
5.1
IN
6V < V < 28V,
IN
LDO5 linear Output Voltage
LDO5 line regulation
LDO5 Current limit
4.9
5.0
V
0 < I
< 50mA
LDO5
V
I
LDO5
6V < V < 28V, I
= 50mA
LDO5
IN
0.004 %/V
LDO3_SEL tied to GND
> UVLO, I = 0A V
OUT5
V
LDO5
LDO3
300
350
400
mA
LDO5
> 5.1V, V
> 3.34V
OUT3
UVLO
Under Voltage Lockout of LDO5
LDO3 linear Ouput Voltage
LDO3 Current limit
3.94
3.23
130
4
4.13
3.37
V
V
V
0 < I
< 50mA
LDO3
3.3
LDO3
I
V
> UVLO
LDO5
200
3
mA
Ω
LDO3
HGATEx high state(pullup)
2.0
1.8
1.4
0.6
HGATE driver on-resistance
LGATE driver on-resistance
HGATEx low state (pulldown)
LGATEx high state(pullup)
LGATEx low state (pulldown)
2.7
2.1
0.9
Ω
Ω
Ω
9/16
4 Electrical characteristics
PM6685
Table 6.
Simbol
Electrical characteristics (continued)
Parameter
Test Condition
Min.
Typ.
Max.
Unit
High side rise time
20
20
40
40
120
72
113
94
1
HGATEx-PHASE from 1V to 4V
CLOAD = 3.3nF
ns
High side fall time
Low side rise time
LGATEx-PGND from 1V to 4V
CLOAD = 8.2nF
ns
OVP
UVP
Over voltage threshold
113
66
116
70
%
%
Both SMPS sections with respect
to VREF.
Under voltage threshold
Upper threshold (VFB-VREF)
Lower threshold (VFB-VREF)
PGOOD leakeage current
107
90
110
92
%
PGOOD3,5
%
I
VPGOOD3,5 forced to 5.5V
ISink = 4mA
µA
PGOOD3,5
V
Ouput Low Voltage
Rising voltage threshold
Falling voltage threshold
Hytseresis
150
2.58
2.55
25
250
mV
V
PGOOD3,5
PGOOD
LDO3
V
mV
I
PGOOD_LD
O3
V
forced to 5.5V
PGOOD leakeage current
Ouput Low Voltage
1
µA
PGOOD LDO3
V
PGOOD_LD
O3
ISink = 4mA
150
250
mV
°C
T
Shutdown Temperature
SMPS disabled level
SMPS enabled level
150
0.8
SDN
EN3,5
FSEL
V
2.4
1.0
Low level
0.5
V
LDO5
Middle level
Frequency selection range
-1.5
V
V
LDO5
High level
-0.8
Always-off level
Boostrap level
0.5
V
LDO5
1.0
3.3V Linear Regulator Selection
Pin
LDO3 SEL
-1.5
V
V
V
LDO5
Always-on level
-0.8
Pulse Skip Mode
PWM Mode
0.5
V
LDO5
1.0
SKIP
-1.5
V
LDO5
Ultrasonic Mode
-0.8
10/16
PM6685
4 Electrical characteristics
Table 6.
Simbol
Electrical characteristics (continued)
Parameter
Test Condition
= 0 to 5V
Min.
Typ.
Max.
Unit
V
TBV
TBV
TBV
TBV
TBV
EN3,4
V
= 0 to 5V
SKIP
I
V
V
V
= 0 to 5V
SHDN
Input leakage current
µA
LEAK
= 0 to 5V
FSEL
LDO3_SEL
= 0 to 5V
11/16
5 Functional & block diagram
PM6685
5
Functional & block diagram
Figure 3. Block diagram
12/16
PM6685
6 Package Mechanical Data
6
Package Mechanical Data
®
In order to meet environmental requirements, ST offers these devices in ECOPACK
packages. These packages have a Lead-free second level interconnect . The category of
second Level Interconnect is marked on the package and on the inner box label, in compliance
with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also
marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are
available at: www.st.com.
13/16
6 Package Mechanical Data
PM6685
Table 7.
Dim.
VFQFPN 5x5x1.0 32L Pitch 0.50
Databook (mm.)
Drawing (mm.)
Typ.
Min.
Typ.
Max
Min.
Max
A
A1
A3
b
0.80
0
0.90
0.02
0.20
0.25
5.00
1.00
0.05
0.80
0
1.00
0.05
0.25
5.00
0.18
4.85
0.30
5.15
0.225
4.90
0.275
5.10
(3)
D
(5)
3.65
4.85
3.65
3.95
5.15
3.95
3.65
4.90
3.65
3.95
5.10
3.95
D2
(3)
5.00
5.00
0.50
E
(5)
E2
e
0.50
0.40
L
0.30
0.50
0.35
0.45
1. – VFQFPN stands for Thermally Enhanced Very thin Fine pitch Quad Flat Package No lead.
___Very thin: A = 1.00mm Max.
2. – The leads size have been increased by Pb/Sn thickness in tin plating electrolytic process.
3. – Dimensions D & E do not include mold protusion, not to exceed 0,15mm.
4. – Package outline exclusive of metal burr dimensions.
5. – Dimensions D2 & E2 are not in accordance with JEDEC.
Figure 4. Scheme Drawings
14/16
PM6685
7 Revision history
7
Revision history
Date
23-Sep-2005
Revision
Changes
1
Initial release.
15/16
7 Revision history
PM6685
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences
of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted
by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject
to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not
authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.
The ST logo is a registered trademark of STMicroelectronics.
All other names are the property of their respective owners
© 2005 STMicroelectronics - All rights reserved
STMicroelectronics group of companies
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www.st.com
16/16
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