RT8204L
Single Synchronous Buck Controller
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
PWM Controller
Ultra High Efficiency
Resistor Programmable Current Limit by Low Side
R
DS(ON)
Sense (Lossless Limit)
4700ppm/°C R
DS(ON)
Current Sensing
°
Quick Load Step Response within 100ns
1% V
FB
Accuracy Over Line and Load
Adjustable 0.75V to 3.3V Output Range
4.5V to 26V Battery Input Range
Resistor Programmable Frequency
Integrated Bootstrap Switch
Over/Under Voltage Protection
Voltage Ramp Soft-Start
Power Good Indicator
LDO Controller
1.5% accuracy Over Line and Load
Independent Enable and Power Good Indicator
Drive N-MOSFETs within Rail to Rail Controller
Voltage
MLCC and POSCAP Stable
RoHS Compliant and Halogen Free
Applications
Notebook Computers
CPU Core Supply
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
Pin Configurations
(TOP VIEW)
TON
EN/DEM
LEN
BOOT
16 15 14 13
J8=YM
DNN
VOUT
VDD
FB
PGOOD
1
2
3
4
5
6
12
GND
17
7
8
11
10
9
UGATE
PHASE
OC
VDDP
J8 : Product Code
J8 YM
DNN
YMDNN : Data Code
WQFN-16L 3x3
Typical Application Circuit
V
IN
4.5V to 26V
R
TON
RT8204L
TON
C4
C3
Q1
L1
R6*
C5*
R7
C6*
C8
V
OUT1
16
V
DDP
5V
BOOT
13
R4
R5
9
VDDP
C1
R1
R2
UGATE
12
2
VDD
C2
PHASE
11
LGATE
8
OC
10
R
ILIM
Q2
PGOOD
CCM/DEM
LDO Enable
LDO PGOOD
R3
V
DDP
4
PGOOD
15
EN/DEM
14
LEN
5
LPGOOD
FB
3
R8
C7*
VOUT
1
C14
V
OUT2
R11
C10
C9
R12
C11*
C12
C13
LDRV
7
R9
R10
Q3
17 (Exposed Pad)
GND
LFB
6
* : Optional
www.richtek.com
2
LPGOOD
LFB
LDRV
LGATE
RT8204LZQW
DS8204L-04 April 2011
RT8204L
Function Block Diagram
VOUT
TON
SS (Internal)
TRIG
On-time
Compute
1-SHOT
+
GM
- -
+
-
+
Comp
R
S
Min. T
OFF
Q
TRIG
Q
DRV
BOOT
UGATE
PHASE
+
OV
115% V
REF
FB
70% V
REF
Latch
S1
Q
Latch
S1
Q
-
1-SHOT
DRV
Diode
Emulation
VDDP
LGATE
PGND
-
+
-
UV
90% V
REF
VDD
GND
SS Ramp
+
Thermal
Shutdown
20µA
+
-
OC
EN/DEM
PGOOD
LEN
0.75V V
REF
SS Ramp
LFB
90% V
REF
+
-
-
+
-
SS
X1
LDRV
LPGOOD
50% V
REF
+
LDO Controller
DS8204L-04 April 2011
www.richtek.com
3
RT8204L
Functional Pin Description
Pin No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Pin Name
VOUT
VDD
FB
PGOOD
LPGOOD
LFB
LDRV
LGATE
VDDP
OC
PHASE
UGATE
BOOT
LEN
Pin Function
Output Voltage Sense Pin. Connect this pin to the output of the PWM converter.
VOUT is an input of the PWM controller.
Analog Supply Voltage Input for Internal Analog Integrated Circuit. Bypass this
pin to GND with a 1μF ceramic capacitor.
Feedback Input of PWM Controller. Connect FB to a resistive voltage divider
from VOUT to GND to adjust the output voltage from 0.75V to 3.3V.
Power Good Signal Open-Drain Output of PWM Controller. This pin will be
pulled high when the output voltage is within the target range.
Power Good Signal Open-Drain Output of the LDO Regulator. This pin will be
pulled high when the output voltage is within the target range.
Feedback Input of LDO Regulator. This pin will be pulled high when the output
voltage is within the target range.
Drive Signal for LDO’s Path MOSFET.
Low Side N-MOSFET Gate-Drive Output for the PWM Controller. This pin
swings between GND to VDDP.
Gate Driver Supply 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 Connection. This pin is not only the zero current sense input for the
PWM converter, but also the UGATE high side gate driver return.
High Side N-MOSFET Floating Gate-Driver Output for PWM Controller. This pin
swings between PHASE and BOOT.
Boost Capacitor Connection for PWM Controller. Connect an external ceramic
capacitor from this pin to PHASE.
LDO Enable Input with Internal Pull Low Resistor. LDO is enabled if LEN voltage
is greater than the Logic High voltage level and disabled if LEN voltage is less
than the Logic Low voltage level.
PWM Enable and Operation Mode Selection Input. Connect to VDD for diode
emulation mode, connect GND for shutdown mode, and float the pin for CCM
mode.
On Time/Frequency Adjustment Pin. Connect this pin to VIN through a resistor.
TON is an input of the PWM controller.
Analog Ground and Power Ground. The exposed pad must be soldered to a
large PCB and connected to GND for maximum power dissipation.
15
16
EN/DEM
TON
17 (Exposed Pad) GND
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4
DS8204L-04 April 2011
RT8204L
Absolute Maximum Ratings
(Note 1)
Input Voltage, TON to GND
------------------------------------------------------------------------------------------------
–0.3V
to 32V
BOOT to PHASE ------------------------------------------------------------------------------------------------------------
–0.3V
to 6V
UGATE to PHASE
DC -------------------------------------------------------------------------------------------------------------------------------
–0.3V
to 6V
< 20ns -------------------------------------------------------------------------------------------------------------------------
−5V
to 7.5V
LGATE to GND
DC -------------------------------------------------------------------------------------------------------------------------------
–0.3V
to 6V
< 20ns -------------------------------------------------------------------------------------------------------------------------
−2.5V
to 7.5V
PHASE to GND
DC -------------------------------------------------------------------------------------------------------------------------------
–0.3V
to 32V
< 20ns -------------------------------------------------------------------------------------------------------------------------
−8V
to 38V
VDD, VDDP, VOUT, EN/DEM, LEN, LFB, FB, PGOOD, LPGOOD, LDRV to GND -------------------------
–0.3V
to 6V
OC to GND --------------------------------------------------------------------------------------------------------------------
–0.3V
to 28V
Power Dissipation, P
D
@ T
A
= 25°C
WQFN-16L 3x3 -------------------------------------------------------------------------------------------------------------- 1.471W
Package Thermal Resistance (Note 2)
WQFN-16L 3x3,
θ
JA
--------------------------------------------------------------------------------------------------------- 68°C/W
WQFN-16L 3x3,
θ
JC
-------------------------------------------------------------------------------------------------------- 7.5°C/W
Lead Temperature (Soldering, 10 sec.) --------------------------------------------------------------------------------- 260°C
Junction Temperature ------------------------------------------------------------------------------------------------------- 150°C
Storage Temperature Range ----------------------------------------------------------------------------------------------
–65°C
to 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Mode) ------------------------------------------------------------------------------------------------ 2kV
MM (Machine Mode) -------------------------------------------------------------------------------------------------------- 200V
Recommended Operating Conditions
(Note 4)
Input Voltage, V
IN
------------------------------------------------------------------------------------------------------------ 4.5V to 26V
Supply Voltage, V
DD,
V
DDP
------------------------------------------------------------------------------------------------ 4.5V to 5.5V
Junction Temperature Range ---------------------------------------------------------------------------------------------
−
40°C to 125°C
Ambient Temperature Range ---------------------------------------------------------------------------------------------
−
40°C to 85°C
Electrical Characteristics
(V
DD
= V
DDP
= 5V, V
IN
= 15V, V
EN/DEM
= V
DD
, R
TON
= 1MΩ, T
A
= 25°C, unless otherwise specified)
Parameter
PWM Controller
Quiescent Current
TON Operating Current
Symbol
Test Conditions
V
DD
+ V
DDP
, V
FB
= 0.8V, forced above
the regulation point
V
DD
+ V
DDP
Min
Typ
Max
Unit
μA
μA
μA
V
I
Q
--
--
--
--
−10
0.742
--
15
1
1
−1
0.75
1250
--
10
5
--
0.758
Shutdown Current
FB Reference Voltage
I
SHDN
V
FB
TON
V
EN/DEM
= 0V
V
DD
= 4.5V to 5.5V
To be continued
DS8204L-04 April 2011
www.richtek.com
5
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