Richtek RT8204LGQW, RT8204LZQW Schematic [ru]
Single Synchronous Buck Controller
RT8204L
General Description
The RT8204L PWM controller provides high efficiency,
excellent transient response, and high DC output accuracy
needed for stepping down high voltage batteries to
generate low voltage CPU core, I/O, and chipset RAM
supplies in notebook computers.
The constant-on-time PWM control scheme handles wide
input/output voltage ratios with ease and provides 100ns
“instant-on” response to load transients while maintaining
a relatively constant switching frequency.
The RT8204L achieves high efficiency at a reduced cost
by eliminating the current sense resistor found in
traditional current mode PWMs. Efficiency is further
enhanced by its ability to drive very large synchronous
rectifier MOSFETs. The buck conversion allows this device
to directly step down high voltage batteries for the highest
possible efficiency. The RT8204L is intended for CPU core,
chipset, DRAM, or other low voltage supplies as low as
0.75V. The RT8204L is available in a WQFN-16L 3x3
package.
A built in LDO controller can drive an external N-MOSFET
to provide a second output voltage from PWM output or
other power source. The RT8204L can provide adjustable
voltage down to 0.75V and maximum output voltage is
dependen on the selected MOSFET. The internal 0.75V
reference voltage with ±1.5% accuracy provides tight
regulation of the output voltage. Other features such as
independent enable control, open drain power good
indicator, under voltage protection, and soft start make
the RT8204L a system friendly power management solution
for various applications.
Features
zz
PWM Controller
z
zz
``
` Ultra High Efficiency
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` Resistor Progra mmable Current Limit by Low Side
``
R
``
` 4700ppm/
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``
` Quick Load Step Response within 100ns
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` 1% V
``
``
` Adjustable 0.75V to 3.3V Output Range
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``
` 4.5V to 26V Battery Input Range
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``
` Resistor Programmable Frequency
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` Integrated Bootstrap Switch
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` Over/Under Voltage Protection
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` Voltage Ramp Soft-Start
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` Power Good Indicator
``
zz
z LDO Controller
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` 1.5% accuracy Over Line and Load
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` Independent Enable and Power Good Indicator
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``
` Drive N-MOSFETs within Rail to Rail Controller
``
Sense (Lossless Limit)
DS(ON)
°°
°C R
°°
Accuracy Over Line and Load
FB
Current Sensing
DS(ON)
Voltage
``
` MLCC and POSCAP Stable
``
zz
z RoHS Compliant and Halogen Free
zz
Applications
z Notebook Computers
z CPU Core Supply
z Chipset/RAM Supply as Low as 0.75V
Ordering Information
RT8204L
Package Type
QW : WQFN-16L 3x3 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Z : ECO (Ecological Element with
Halogen Free and Pb free)
Note :
Richtek 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.
DS8204L-04 April 2011 www.richtek.com
1
RT8204L
Marking Information
RT8204LGQW
J8= : Product Code
YMDNN : Data Code
J8=YM
DNN
RT8204LZQW
J8 : Product Code
YMDNN : Data Code
J8 YM
DNN
Typical Application Circuit
Pin Configurations
VOUT
VDD
FB
PGOOD
V
N
I
V
5
.
4
o
2
t
6
V
R
T
O
N
(TOP VIEW)
TON
EN/DEM
BOOT
LEN
13141516
1
2
GND
3
4
WQFN-16L 3x3
17
LFB
LDRV
LPGOOD
8765
LGATE
12
11
10
9
UGATE
PHASE
OC
VDDP
C
R
T
8
0
2
4
16
O
N
T
V
P
D
D
V
5
O
G
P
C
C
D
M
/
D
O
L
E
n
a
L
P
D
O
G
O
V
1
C
D
O
M
E
b
e
l
O
D
D
D
P
1
R
3
R
17 (Exposed Pad)
:
*
O
p
o
i
t
9
V
D
D
P
2
R
2
D
D
V
2
C
4
O
O
G
P
15
E
D
N
E
/
14
L
E
N
5
L
P
O
G
D
G
N
n
a
l
L
B
O
T
O
U
G
A
T
E
P
H
S
A
E
L
G
A
T
E
O
C
D
M
O
D
F
B
V
O
U
T
L
D
R
V
L
F
B
13
12
11
8
10
3
1
7
6
R
4
C
R
5
R
I
I
L
M
R
C
3
Q
Q
2
3
Q
R
1
9
0
R
1
C
1
9
1
0
R
1
2
4
V
O
U
T
1
1
L
1
6
R
*
R
7
C
5
*
C
1
C
1
2
1
*
C
6
*
R
8
C
C
V
O
U
T
1
3
C
8
7
*
C
1
4
2
DS8204L-04 April 2011www.richtek.com
2
Function Block Diagram
TRIG
+
+
GM
-
-
SS Ramp
On-time
Compute
1-SHOT
+
-
+
-
90% V
OV
UV
VOUT
TON
FB
VDD
GND
SS (Internal)
115% V
70% V
REF
REF
+
Latch
S1 Q
Latch
S1 Q
REF
Thermal
Shutdown
Comp
+
R
QS
Min. T
OFF
QTRIG
1-SHOT
Emulation
Diode
RT8204L
BOOT
DRV
DRV
20µA
+
-
UGATE
PHASE
VDDP
LGATE
PGND
OC
EN/DEM
LEN
LFB
0.75V V
SS Ramp
90% V
50% V
REF
+
-
+
REF
-
REF
+
LDO Controller
SS
X1
PGOOD
LDRV
LPGOOD
DS8204L-04 April 2011 www.richtek.com
3
RT8204L
Functional Pin Description
Pin No. Pin Name Pin Function
1 VOUT
2 VDD
3 FB
4 PGOOD
5 LPGOOD
6 LFB
7 LDRV Drive Signal for LDO’s Path MOSFET.
8 LGATE
9 VDDP
10 OC
11 PHASE
12 UGATE
13 BOOT
14 LEN
15 EN/DEM
16 TON
17 (Exposed Pad) GND
Output Voltage Sense Pin. Connect this pin to the output of the PWM converter.
VOUT is an inp ut of the PWM controller.
Analog Supply Voltage Inpu t for Internal Analog In tegrated Circuit. Bypass this
pin to GND with a 1μF ceramic capacitor.
Feedback Input o f PWM Cont roll er. Conn ect FB to a resistive voltage divider
from VOUT to GND t o adjust the output voltage from 0.75V to 3 .3V.
Power Good Signal Open-Drain Output of PW M Cont roller. Th is pin will be
pulled high when the ou tput voltage is within the target r ange .
Power Good Signal Open-Drain Output of the LDO Regulat or. This pin will be
pulled high when the ou tput voltage is within the target range.
Feedback Input of LDO Reg ulator. Th is pin will b e pulled high when the outp ut
voltage is within the target range.
Low Side N-MOSFET Gate-Drive Output for the PWM Controller. This pin
swings between GND to V DDP.
Gate Driver Su pply for external MOSFETs. Bypass this pin to GND with a 1μF
ceramic capacitor.
PWM Current Limit Setting and Sense. Connect a resistor between OC to
PHASE for current limit setting.
Inductor Connect ion. This p in is no t only the zero cur rent se nse inpu t for t he
PWM converter, but also the UGATE high s ide gate driver retu rn.
High Side N-MOSFET Floating Gate-Driver Output for PWM Controller. This pin
swings between PHASE and BOOT.
Boost Capacitor Connecti on for PWM Controller. Connect an external ceram ic
capacitor fro m this pin to PHASE.
LDO Enable Inp ut with In ternal Pull Low Resistor. LDO is enabled if LEN voltage
is greater than t he Logic Hi gh voltage level and disabled if LEN voltag e is les s
than the L ogic Low volt age level.
PWM Enable and Operation Mode Selec tion Input. Connect to VDD for diode
emula tion mode, connect GND for shutdown mo de, and float the pin for CCM
mode .
On Time/Fre quency Adjustment Pin. Connect this pin to VIN through a resistor.
TON is an input of the PWM controller.
Analog Grou nd and Power Groun d. Th e exposed pad must be soldered to a
large PCB and connected to GND for maximum power dissipation.
DS8204L-04 April 2011www.richtek.com
4
RT8204L
Absolute Maximum Ratings (Note 1)
z Input Voltage, TON to GND ------------------------------------------------------------------------------------------------ –0.3V to 32V
z BOOT to PHASE ------------------------------------------------------------------------------------------------------------ –0.3V to 6V
z UGATE to PHASE
DC------------------------------------------------------------------------------------------------------------------------------- –0.3V to 6V
< 20ns ------------------------------------------------------------------------------------------------------------------------- −5V to 7.5V
z LGATE to GND
DC------------------------------------------------------------------------------------------------------------------------------- –0.3V to 6V
< 20ns ------------------------------------------------------------------------------------------------------------------------- −2.5V to 7.5V
z PHASE to GND
DC------------------------------------------------------------------------------------------------------------------------------- –0.3V to 32V
< 20ns ------------------------------------------------------------------------------------------------------------------------- −8V to 38V
z VDD, VDDP, VOUT, EN/DEM, LEN, LFB, FB, PGOOD, LPGOOD, LDRV to GND ------------------------- –0.3V to 6V
z OC to GND -------------------------------------------------------------------------------------------------------------------- –0.3V to 28V
z Power Dissipation, P
WQFN-16L 3x3 -------------------------------------------------------------------------------------------------------------- 1.471W
z Package Thermal Resistance (Note 2)
WQFN-16L 3x3, θJA--------------------------------------------------------------------------------------------------------- 68°C/W
WQFN-16L 3x3, θJC-------------------------------------------------------------------------------------------------------- 7.5°C/W
z Lead Temperature (Soldering, 10 sec.) --------------------------------------------------------------------------------- 260°C
z Junction Temperature ------------------------------------------------------------------------------------------------------- 150°C
z Storage Temperature Range ---------------------------------------------------------------------------------------------- –65°C to 150°C
z ESD Susceptibility (Note 3)
HBM (Human Body Mode) ------------------------------------------------------------------------------------------------ 2kV
MM (Machine Mode) -------------------------------------------------------------------------------------------------------- 200V
@ TA = 25°C
D
Recommended Operating Conditions
z Input Voltage, V
z Supply Voltage, V
z Junction Temperature Range --------------------------------------------------------------------------------------------- −40°C to 125°C
z Ambient Temperature Range --------------------------------------------------------------------------------------------- −40°C to 85°C
------------------------------------------------------------------------------------------------------------ 4.5V to 26V
IN
DD, VDDP
------------------------------------------------------------------------------------------------ 4.5V to 5.5V
(Note 4)
Electrical Characteristics
(VDD = V
PWM Controller
Quiescent Current IQ
TON Operating Current -- 15 -- μA
Shutdown Current I
FB Reference Voltage VFB V
= 5V, VIN = 15V, V
DDP
EN/DEM
= VDD, R
= 1MΩ, T
TON
= 25°C, unless otherwise specified)
A
Parameter Symbol Test Conditions Min Typ Max Unit
V
SHDN
+ V
DD
the regulati on point
VDD + V
TON -- 1 5
V
EN/DEM
= 4.5V to 5.5V 0.742 0.75 0.758 V
DD
, VFB = 0.8 V, forced abo ve
DDP
-- 1 10
DDP
-- -- 1250 μA
μA
= 0V −10 −1 --
To be continued
DS8204L-04 April 2011 www.richtek.com
5
RT8204L
Parameter Symbol Test Conditions Min Typ Max Unit
FB Input Bias Current VFB = 0.75V −1 0.1 1 μA
Output Voltage Range V
On-Time
Minimum Off-Time 250 400 550 ns
VOUT Shutdown Discharge
Resistance
Current Sensing
Current Limit Source Current LGATE = High 18 20 22 μA
0.75 -- 3.3 V
OUT
= 15V, V
V
IN
R
TON
= 1MΩ
= 1.25V,
OUT
267 334 401 ns
EN/DEM = GND -- 20 -- Ω
Current Limiter Temperature
Coefficient
Current Comparator Offset
Voltage
Zero Crossing Threshold
Voltage
TC
On the basis of 25°C -- 4700 -- ppm/°C
ICS
GND to OC −10 -- 10 mV
PHASE to GND, V
EN/ DEM
= 5V −10 -- 5 mV
Fault Pr otection
Current Limit Sense Voltage GND − PHASE, R
Output Under Voltage Threshold V
Over Voltage Protection
Threshold
60 70 80 %
UVP
V
OVP
With respect to error comparator
threshold
= 10kΩ 170 200 230 mV
ILIM
110 115 120 %
Over Voltage Fault Delay FB forced above OV threshold -- 20 -- μs
Under Voltage Lockout
Threshold
Under Voltage Lockout
Hysteresis
-- 150 -- mV
Soft-Start Ramp Time tSS
Falling edge, PWM disabled below
this level
From EN high to internal V
REF
reaches 0.71V (0Æ95%)
3.7 3.9 4.1 V
-- 1.5 -- ms
Under Voltage Blank Time From EN signal going high -- 4.5 -- ms
Thermal Shutdown T
Thermal Shutdown Hysteresis ΔT
SD_PWM
-- 155 -- °C
SD_PWM
-- 10 -- °C
Driver On-Resistance
UGATE Driver Source R
UGATE Driver Sink R
LGATE Driver Source R
LGATE Driver Sink R
Dead Time
Internal BOOT Charging Switch
On Resistance
Logic I/O
EN/DEM Input
Threshold Voltage
Logic-Low VIL EN/DEM Low -- -- 0.8
Logic-High V
6
UGATEsr
UGATEsk
LGATE sr
LGATE sk
BOOT to PHASE forced to 5V -- 2 -- Ω
BOOT to PHASE forced to 5V -- 1.5 -- Ω
LGATE, High State -- 1.5 -- Ω
LGATE, Low State -- 0.7 -- Ω
LGATE Rising (V
UGATE Rising -- 30 --
= 1.5V) -- 30 --
PHASE
ns
VDDP to BOOT, 10mA -- -- 90 Ω
IH
EN/DEM High 2.9 -- -EN/DEM Float -- 2 --
V
To be continued
DS8204L-04 April 2011www.richtek.com
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