RT8204BGQW Richtek USA Inc, RT8204BGQW Datasheet

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RT8204BGQW

Manufacturer Part Number
RT8204BGQW
Description
IC SYNC BUCK W/LDO CTRLR 16WQFN
Manufacturer
Richtek USA Inc
Datasheet

Specifications of RT8204BGQW

Topology
Step-Down (Buck) Synchronous (1), Linear (LDO) (1)
Function
Any Function
Number Of Outputs
2
Voltage/current - Output 1
Controller
Voltage/current - Output 2
Controller
W/led Driver
No
W/supervisor
No
W/sequencer
No
Voltage - Supply
4.5 V ~ 5.5 V
Operating Temperature
-40°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
16-WFQFN Exposed Pad
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Single Synchronous Buck with LDO Controller
General Description
The RT8204B PWM controller provides the 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 RT8204B 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 RT8204B is intended for CPU core,
chipset, DRAM, or other low voltage supplies as low as
0.75V.
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 RT8204B can provide adjustable
voltage down to 0.75V and maximum output voltage is
depended on the selected MOSFET. The internal 0.75V
reference voltage with ±1.5% accuracy provides tight
regulation for the output voltage. The independent enable
control, open drain power good indicator, under voltage
protection and soft start make RT8204B to power the
system friendly. The RT8204B is available in WQFN-16L
3x3 package.
Applications
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area, otherwise visit our website for detail.
DS8204B-03 March 2011
Notebook Computers
CPU Core Supply
Chipset/RAM Supply as Low as 0.75V
Features
Ordering Information
Note :
Richtek Green products are :
RT8204B
PWM Controller
LDO Controller
RoHS Compliant and Halogen Free
ments of IPC/JEDEC J-STD-020.
RoHS compliant and compatible with the current require-
Suitable for use in SnPb or Pb-free soldering processes.
Resistor Programmable Current Limit by Low Side
R
(High Accuracy)
Voltage
Ultra-High Efficiency
Drives Large Synchronous-Rectifier FETs
Quick Load Step Response within 100ns
1% V
Adjustable 0.75V to 3.3V Output Range
3V to 26V Battery Input Range
2 Steps Current Limit During Soft-Start
1.5% Accuracy Over Line and Load
Adjustabe Output Voltage down to 0.75V
Drive N-MOSFETs within Rail to Rail Controller
MLCC and POSCAP Stable
Resistor Programmable Frequency
Over/Under Voltage Protection
Power-Good Indicator
Independent Enable and Power Good Indicator
DS(ON)
OUT
Sense (Lossless Limit) or Sense Resistor
Accuracy Over Line and Load
Package Type
QW : WQFN-16L 3x3 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
RT8204B
www.richtek.com
1

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RT8204BGQW Summary of contents

Page 1

Single Synchronous Buck with LDO Controller General Description The RT8204B PWM controller provides the 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 ...

Page 2

RT8204B Pin Configurations Typical Application Circuit LEN LPGOOD www.richtek.com 2 (TOP VIEW UGATE VOUT 12 1 VDD PHASE 11 2 GND VDDP PGOOD WQFN-16L 3x3 ...

Page 3

Functional Pin Description Pin No. Pin Name 1 VOUT 2 VDD PGOOD 5 LPGOOD 6 LFB 7 LDRV 8 LGATE 9 VDDP PHASE 12 UGATE 13 BOOT 14 LEN 15 EN/DEM 16 TON 17 ...

Page 4

RT8204B Function Block Diagram PWM Controller TRIG On-time VOUT Compute TON 1-SHOT SS + (Internal 0.75V V REF + 115% V REF - FB - 70% V REF + SS Timer VDD GND EN/DEM LDO Controller ...

Page 5

Absolute Maximum Ratings Input Voltage, TON to GND ---------------------------------------------------------------------------------------------- BOOT to GND -------------------------------------------------------------------------------------------------------------- PHASE to BOOT ---------------------------------------------------------------------------------------------------------- PHASE to GND DC ----------------------------------------------------------------------------------------------------------------------------- −0.3V to 32V <20ns ------------------------------------------------------------------------------------------------------------------------ −8V to 38V VDD, VDDP, VOUT, EN/DEM, LEN, LFB, FB, PGOOD, LPGOOD, LDRV ...

Page 6

RT8204B Parameter Output Voltage Range On-Time Minimum Off-Time V Shutdown Discharge OUT Resistance Current Sensing I Source Current LIM Current Comparator Offset Zero Crossing Threshold Fault Protection Current Limit Sense Voltage Output UV Threshold OVP Threshold OV Fault Delay VDD ...

Page 7

Parameter PGOOD (upper side threshold decide by OV threshold) Trip Threshold (Falling) Fault Propagation Delay Output Low Voltage Leakage Current LDO Controller Quiescent Current I Shut-down Current I Input Voltage UVLO LEN Logic High Voltage V LEN Logic Low Voltage ...

Page 8

RT8204B Typical Operating Characteristics VOUT1 Efficiency vs. Load Current 100 90 80 DEM 0.001 0.01 Load Current (A) VOUT1 Efficiency vs. Load Current 100 90 80 DEM ...

Page 9

LDO Output Voltage vs. Output Current 1.0540 1.0535 1.0530 1.0525 1.0520 1.0515 1.0510 1.0505 1.0500 0 0.5 1 1.5 2 Output Current (A) Shutdown Current vs. Input Voltage 3.0 2.5 2.0 1.5 1.0 0.5 0 ...

Page 10

RT8204B VOUT1 Load Transient Response V OUT_ac (50mV/Div) I LOAD (5A/Div) UGATE (20V/Div) LGATE (5V/Div 12V Floating Time (10μs/Div) V OUT (1V/Div) Inductor Current (10A/Div) UGATE (20V/Div) LGATE (5V/Div Time (20μs/Div) LDO ...

Page 11

LDO Short-Circuit Protection V OUT (1V/Div) LDRI (5V/Div) I LOAD (20A/Div) LPGOOD (5V/Div 1.25V Time (100μs/Div) DS8204B-03 March 2011 = 10μ Short OUT OUT2 RT8204B www.richtek.com 11 ...

Page 12

RT8204B Application Information The RT8204B PWM controller provides the 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. ...

Page 13

The switching waveforms may appear noisy and asynchronous when light loading causes diode-emulation operation, but this is a normal operating condition that results in high light-load efficiency. Trade-off in DEM noise vs. light-load efficiency is made by varying the inductor ...

Page 14

RT8204B MOSFET Gate Driver (UGATE, LGATE) The high side driver is designed to drive high current, low R N-MOSFETs. When configured as a floating driver, DS(ON) 5V bias voltage is delivered from VDDP supply. The average drive current is proportional ...

Page 15

R1 × + ⎜ ⎟ OUT FB ⎢ ⎥ R2 ⎝ ⎠ ⎣ ⎦ where V is 0.75V. FB Note that in order for the device to regulate in a controlled manner, ...

Page 16

RT8204B Find a low pass inductor having the lowest possible DC resistance that fits in the allowed dimensions. Ferrite cores are often the best choice, although powdered iron is inexpensive and can work well at 200kHz. The core must be ...

Page 17

The RT8204B LDO contains a power good output pin (LPGOOD pin) which is an open drain output that will be pulled low if the output is below the power good threshold (typically 90% of the programmed output voltage, or 93% ...

Page 18

RT8204B LDO_VIN LDRV R3 LFB R4 Figure 8. LDO Output Voltage Setting LDO Output Capacitor Selection Low ESR capacitors such as Sanyo POSCAPs or Panasonic SP-caps are recommended for bulk capacitance, and ceramic bypass capacitors are recommended for decoupling high ...

Page 19

Outline Dimension Symbol Richtek Technology Corporation Headquarter 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Information that is provided by ...

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