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RT8205A/B/C
High-Efficiency, Main Power Supply Controllers
for Notebook Computers
General Description
Features
z
Wide Input Voltage Range 6V to 25V
The RT8205A/B/C dual step-down, switch-mode power-
supply controller generates logic-supply voltages in
battery-powered systems. The RT8205A/B/C includes two
pulse-width modulation (PWM) controllers fixed at 5V/
3.3V or adjustable from 2V to 5.5V. An alternative LGATE1
output LG1_CP can be used for external charge pump
(RT8205B). And an optional external charge pump can be
monitored through SECFB (RT8205C). This device also
features 2 linear regulators providing fixed 5V and 3.3V
outputs. The linear regulator each provides up to 70mA
output current with automatic linear-regulator bootstrapping
to the PWM outputs. The RT8205A/B/C includes on-board
power-up sequencing, the power-good output, internal soft-
start, and internal soft-discharge output that prevents
negative voltages on shutdown.
z
Dual Fixed 5V/3.3V Outputs or Adjustable from 2V
to 5.5V, 1.5% Accuracy.
z
Alternative LGATE1 Output (LG1_CP) acts as Clock
for Charge Pump (RT8205B)
z
Secondary Feedback Input Maintains Charge Pump
Voltage (RT8205C).
z
Fixed 3.3V and 5V LDO Output : 70mA
z
2V Reference Voltage
±
1% : 50uA
z
Constant ON-Time Control with 100ns Load Step
Response
z
Frequency Selectable via TONSEL Setting
z
R
DS(ON)
Current Sensing and Programmable Current
Limit combined with Enable Control
z
Selectable PWM, DEM, or Ultrasonic Mode
z
Internal Soft-Start and Soft-Discharge
A constant on-time PWM control scheme operates without
sense resistor and provides 100ns response to load
transients while maintaining a relatively constant switching
frequency. The unique ultrasonic mode maintains the
switching frequency above 25kHz, which eliminates noise
in audio applications. Other features include diode-
emulation mode (DEM), which maximizes efficiency in
light-load applications, and fixed-frequency PWM mode,
which reduces RF interference in sensitive application
z
High Efficiency up to 97%
z
5mW Quiescent Power Dissipation
z
Thermal Shutdown
z
RoHS Compliant and Halogen Free
Applications
z
Notebook and Sub-Notebook Computers
z
3-Cell and 4-Cell Li+ Battery-Powered Devices
Marking Information
Ordering Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area, otherwise visit our website for detail.
RT8205
Package Type
QW : WQFN-24L 4x4 (W-Type)
Operating Temperature Range
G : Green (Halogen Free with Commer-
cial Standard)
Pin Function
A : Default
B : With LG1_CP
C : With SECFB
Note :
Richtek Green products are :
`
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
`
Suitable for use in SnPb or Pb-free soldering processes.
DS8205A/B/C-03 April 2009
www.richtek.com
1
RT8205A/B/C
Pin Configurations
(TOP VIEW)
24
23
22
21
20
19
24
23
22
21
20 19
24
23
22
21
20 19
ENTRIP1
FB1
REF
TONSEL
FB2
ENTRIP2
NC
VREG5
1
2
3
4
5
6
18
17
16
15
14
13
ENTRIP1
FB1
REF
TONSEL
FB2
ENTRIP2
LG1_CP
VREG5
ENTRIP1
FB1
REF
TONSEL
FB2
ENTRIP2
SECFB
VREG5
1
2
3
4
5
6
18
17
16
15
14
13
1
2
3
4
5
6
18
17
16
15
14
13
VIN
VIN
VIN
GND
GND
GND
GND
SKIPSEL
EN
PGND
SKIPSEL
EN
PGND
SKIPSEL
EN
25
25
25
789 0
11
2
789 0
11
2
789 0
11
2
RT8205A
WQFN-24L 4x4
RT8205B
WQFN-24L 4x4
RT8205C
WQFN-24L 4x4
Typical Application Circuit
For Fixed Voltage Regulator
R7
3.9
C1
RT8205A
10uF
Q2
10
16
UGATE2
VIN
BSC119
N03S
C6
0.1uF
9
BOOT2
R4
0
Q1
21
UGATE1
11
BSC119
N03S
PHASE2
LGATE2
R
3 0
Q4
BSC119
N03S
22
12
BOOT1
C2
L1
0.1uF
6
.8uH
V
OUT1
5V
20
PHASE1
LGATE1
7
VOUT2
19
Q3
BSC119
N03S
C3
R5
17
VREG5
220uF
C4
23
24
PGOOD
VOUT1
8
3
REF
VREG3
C11
0.22uF
1
4
14
ENTRIP1
TONSEL
Frequency Control
PWM/DEM/Ultrasonic
SKIPSEL
6
ENTRIP2
13
ON
EN
15, Exposed Pad (25)
2
5
OFF
FB1
GND
FB2
www.richtek.com
DS8205A/B/C-03 April 2009
2
RT8205A/B/C
R7
3.9
C1
RT8205B
10uF
Q2
10
16
UGATE2
VIN
BSC119
N03S
C10
0.1uF
9
BOOT2
R4
0
21
Q1
UGATE1
11
BSC119
N03S
PHASE2
LGATE2
R
3 0
12
Q4
BSC119
N03S
22
BOOT1
C2
L1
0.1uF
6
.8uH
V
OUT1
20
PHASE1
LGATE1
5V
7
VOUT2
19
Q3
BSC119
N03S
C3
R5
17
VREG5
220u
F
C4
23
24
PGOOD
VOUT1
C5
8
D
1
VREG3
18
C6
LG1_CP
1
ENTRIP1
C7
3
REF
D3
C15
0.22uF
6
D4
ENTRIP2
15
ON
BAT254
C8
13
PGND
EN
OFF
2
5
Exposed Pad (25)
CP
FB1
4
14
TONSEL
SKIPSEL
Frequency Control
FB2
PWM/DEM/Ultrasonic
GND
R8
3.9
C1
RT8205C
10uF
10
Q2
16
UGATE2
VIN
BSC119
N03S
C10
0.1uF
9
BOOT2
R4
0
Q1
21
UGATE1
11
BSC119
N03S
PHASE2
LGATE2
R
3 0
Q4
BSC119
N03S
22
12
BOOT1
C2
L1
0.1uF
6
.
8u
H
V
OUT1
20
PHASE1
LGATE1
7
VOUT2
19
Q3
BSC119
N03S
C3
R5
17
VREG5
220uF
C4
23
24
PGOOD
VOUT1
C5
8
D
1
VREG3
3
REF
C6
C15
0.22uF
1
ENTRIP1
C7
D
3
2
5
FB1
6
D
4
ENTRIP2
FB2
4
14
R6
BAT254
TONSEL
SKIPSEL
C8
18
SECFB
PWM/DEM/Ultrasonic
R7
15
PGND
CP
C18
Exposed Pad (25)
ON
GND
13
EN
OFF
DS8205A/B/C-03 April 2009
www.richtek.com
3
RT8205A/B/C
For Adjustable Voltage Regulator
R7
3.9
C1
RT8205A
10uF
Q2
10
16
UGATE2
VIN
BSC119
N03S
C6
0.1uF
9
BOOT2
R4
0
Q1
21
UGATE1
11
BSC119
N03S
PHASE2
LGATE2
R
3 0
12
Q4
BSC119
N03S
22
BOOT1
C2
L1
0.1uF
6
.8uH
V
OUT1
5V
20
PHASE1
LGATE1
7
VOUT2
19
Q3
BSC119
N03S
C3
5
R5
C
17
FB2
R13
6.5k
220uF
C4
1
C16
0.1uF
ENTRIP1
24
R14
10k
VOUT1
C
14
R11
15k
6
ENTRIP2
2
FB1
15, Exposed Pad (25)
GND
C15
0.1uF
3
R12
10k
REF
C11
0.22uF
17
VREG5
4
14
TONSEL
SKIPSEL
Frequency Control
PWM/DEM/Ultrasonic
23
PGOOD
8
VREG3
13
ON
EN
OFF
R7
3.9
C1
RT8205B
10uF
Q2
10
16
UGATE2
VIN
BSC119
N03S
C10
0.1uF
9
BOOT2
R4
0
21
Q1
UGATE1
11
BSC119
N03S
PHASE2
LGATE2
R
3
0
12
Q4
BSC119
N03S
22
BOOT1
C2
L1
0.1uF
6
.8uH
V
OUT1
20
PHASE1
LGATE1
7
5V
VOUT2
19
Q3
BSC119
N03S
C3
R5
C
21
R13
6.5k
220uF
C4
5
FB2
C20
0.1uF
24
R14
10k
VOUT1
1
ENTRIP1
C
18
R11
1
5k
2
FB1
6
ENTRIP2
C19
0.1uF
C5
R12
10k
D
1
Exposed Pad (25)
18
GND
C6
LG1_CP
17
C7
VREG5
3
D
3
REF
C15
0.22uF
D4
23
PGOOD
BAT254
C8
ON
8
13
VREG3
EN
OFF
CP
4
14
TONSEL
SKIPSEL
Frequency Control
15
PGND
PWM/DEM/Ultrasonic
www.richtek.com
DS8205A/B/C-03 April 2009
4
RT8205A/B/C
R8
3.9
C1
RT8205C
10uF
Q2
10
16
UGATE2
VIN
BSC119
N03S
C10
0.1uF
9
BOOT2
R4
0
Q1
21
UGATE1
11
BSC119
N03S
PHASE2
LGATE2
R
3 0
12
Q4
BSC119
N03S
22
BOOT1
C2
L1
0.1uF
6.8uH
20
V
O
UT1
PHASE1
LGATE1
7
VOUT2
19
Q3
BSC119
N03S
C3
R5
C
21
R14
6.5k
220uF
C4
5
C20
0.1uF
FB2
24
R15
10k
VOUT1
1
ENTRIP1
C
18
R12
15k
2
FB1
6
ENTRIP2
C19
0.1uF
R13
10k
C5
Exposed Pad (25)
D
1
GND
3
C6
REF
17
C
15
0.22uF
VREG5
C7
D
3
23
PGOOD
D4
8
VREG3
R6
BAT254
C8
18
SECFB
4
14
TONSEL
R7
CP
SKIPSEL
PW
M/DEM/Ultrasonic
C18
ON
15
13
EN
PGND
OFF
DS8205A/B/C-03 April 2009
www.richtek.com
5
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