®
RT8202/A/B
Single Synchronous Buck Controller
General Description
The RT8202/A/B 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 RT8202/A/B 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 RT8202/A/B is intended for CPU core, chipset, DRAM, or other low voltage supplies as low as 0.75V. RT8202 is available in WQFN-16L 4x4, RT8202A is available in WQFN-16L 3x3 and RT8202B is available in WQFN-14L 3.5x3.5 packages.
Features
Ultra-High Efficiency
Resistor Programmable Current Limit by Low Side RDS(ON) Sense (Lossless Limit) or Sense Resistor (High Accuracy)
Quick Load Step Response within 100ns
1% VOUT Accuracy over Line and Load
Adjustable 0.75V to 3.3V Output Range
4.5V to 26V Battery Input Range
Resistor Programmable Frequency
Over/Under Voltage Protection
2 Steps Current Limit During Soft-Start
Drives Large Synchronous-Rectifier FETs
Power Good Indicator
RoHS Compliant and 100% Lead (Pb)-Free
Applications
Notebook Computers
CPU Core Supply
Chipset/RAM Supply as Low as 0.75V
Pin Configurations
Ordering Information |
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(TOP VIEW) |
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EN/DEM |
NC |
BOOT |
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RT8202/A/B |
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Package Type |
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16 |
15 |
14 |
13 |
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VOUT |
1 |
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12 |
UGATE |
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QW : WQFN-16L 4x4 (W-Type) (RT8202) |
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VDD |
2 |
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11 |
PHASE |
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QW : WQFN-16L 3x3 (W-Type) (RT8202A) |
GND |
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FB |
3 |
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10 |
OC |
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QW : WQFN-14L 3.5x3.5 (W-Type) (RT8202B) |
PGOOD |
4 |
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17 |
9 |
VDDP |
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Lead Plating System |
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5 |
6 |
7 |
8 |
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NC |
GND |
PGND |
LGATE |
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P : Pb Free |
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G : Green (Halogen Free and Pb Free) |
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Note : |
WQFN-16L 4x4/WQFN-16L 3x3 |
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Richtek products are : |
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EN/DEM |
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BOOT |
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RoHS compliant and compatible with the current require- |
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ments of IPC/JEDEC J-STD-020. |
TON |
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14 |
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UGATE |
Suitable for use in SnPb or Pb-free soldering processes. |
2 |
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VOUT |
3 |
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12 |
PHASE |
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Marking Information |
VDD |
4 |
GND |
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11 |
OC |
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FB |
5 |
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15 |
10 |
VDDP |
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PGOOD |
6 |
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9 |
LGATE |
For marking information, contact our sales representative |
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7 |
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8 |
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GND |
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PGND |
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directly or through a Richtek distributor located in your |
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area. |
WQFN-14L 3.5x3.5 |
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Copyright ©2014 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
DS8202/A/B-07 April 2014 |
www.richtek.com |
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1 |
RT8202/A/B
Typical Application Circuit
VDDP
5V
PGOOD
CCM/DEM
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D1 |
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VIN |
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BAT254 |
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4.5V to 26V |
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C1 |
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R3 |
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1µF |
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1M |
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R2 |
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R4 |
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C4 |
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51k |
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RT8202/A/B |
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10µF |
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2.2 |
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TON |
BOOT |
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C3 |
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V |
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VDDP |
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R5 |
0 |
0.1µF |
Q1 |
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OUT |
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R1 |
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UGATE |
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AO4702 |
L1 |
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2.4µH |
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10 |
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PHASE |
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VDD |
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C2 |
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C7 |
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LGATE |
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R7 |
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1µF |
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Q2 |
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R6 |
10k |
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C6 |
220µF |
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PGOOD |
OC |
AO4702 |
C5 |
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R8 |
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EN/DEM |
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12k |
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FB |
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GND |
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C8 |
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R9 |
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VOUT |
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0.1µF |
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20k |
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PGND |
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Figure 1. Output Voltage Setting for VOUT < 3.3V Application
VDDP
5V
PGOOD
CCM/DEM
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D1 |
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VIN |
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BAT254 |
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4.5V to 26V |
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C1 |
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R3 |
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1µF |
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1M |
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R2 |
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R4 |
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C4 |
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51k |
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RT8202/A/B |
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10µF |
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2.2 |
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TON |
BOOT |
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C3 |
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V |
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VDDP |
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R5 |
0 |
0.1µF |
Q1 |
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OUT |
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R1 |
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UGATE |
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AO4702 |
L1 |
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2.4µH |
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10 |
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PHASE |
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VDD |
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C2 |
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C7 |
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LGATE |
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R7 |
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1µF |
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Q2 |
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R6 10k |
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C6 |
220µF |
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PGOOD |
OC |
AO4702 |
C5 |
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R8 |
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EN/DEM |
FB |
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GND |
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C8 |
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R9 |
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0.1µF |
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VOUT |
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R10 |
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PGND |
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V |
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OUT FB |
R11 |
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Figure 2. Output Voltage Setting for VOUT > 3.3V Application
Copyright ©2014 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
www.richtek.com |
DS8202/A/B-07 April 2014 |
2 |
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RT8202/A/B
Functional Pin Description
Pin No. |
Pin Name |
Pin Function |
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RT8202/A |
RT8202B |
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1 |
3 |
VOUT |
VOUT Sense Input. Connect to the output of PWM converter. VOUT |
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is an input of the PWM controller. |
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2 |
4 |
VDD |
Analog Supply Voltage Input for the internal analog integrated circuit. |
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Bypass to GND with a 1 F ceramic capacitor. |
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3 |
5 |
FB |
VOUT Feedback Input. Connect FB to a resistor voltage divider from |
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VOUT to GND to adjust the output from 0.75V to 3.3V. |
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4 |
6 |
PGOOD |
Power Good Signal Open-Drain Output of PWM Converter. This pin |
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will be pulled high when the output voltage is within the target range. |
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5, 14 |
-- |
NC |
No Internal Connection. |
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6, 17 |
7, 15 |
GND |
Ground for Analog Circuitry. The exposed pad must be soldered to a |
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(Exposed Pad) |
(Exposed Pad) |
large PCB and connected to GND for maximum power dissipation. |
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7 |
8 |
PGND |
Power Ground. |
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8 |
9 |
LGATE |
Low side N-MOSFET Gate-Drive Output for PWM. This pin swings |
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between GND and VDDP. |
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9 |
10 |
VDDP |
VDDP is the gate driver supply for the external MOSFETs. Bypass to |
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GND with a 1 F ceramic capacitor. |
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10 |
11 |
OC |
PWM Current Limit Setting and sense. Connect a resistor between |
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OC to PHASE for current limit setting. |
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11 |
12 |
PHASE |
Inductor Connection. This pin is not only the zero-current-sense input |
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for the PWM converter, but also the UGATE high side gate driver |
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return. |
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12 |
13 |
UGATE |
High Side N-MOSFET Floating Gate-Driver Output for the PWM |
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converter. This pin swings between PHASE and BOOT. |
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13 |
14 |
BOOT |
Boost Capacitor Connection for PWM Converter. Connect an external |
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ceramic capacitor to PHASE and an external diode to VDDP. |
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PWM Enable and Operation Mode Selection Input. Connect to VDD |
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15 |
1 |
EN/DEM |
for diode-emulation mode, connect to GND for shutdown mode and |
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floating the pin for CCM mode. |
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16 |
2 |
TON |
VIN Sense Input. Connect to VIN through a resistor. TON is an input |
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of the PWM controller. |
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Copyright ©2014 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
DS8202/A/B-07 April 2014 |
www.richtek.com |
|
3 |
RT8202/A/B
Function Block Diagram
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TRIG |
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VOUT |
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On-time |
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Compute |
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TON |
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1-SHOT |
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R |
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+ |
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- Comp |
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BOOT |
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SS(Internal) |
- |
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GM |
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S |
Q |
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UGATE |
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+ |
- |
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+ |
DRV |
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PHASE |
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0.75V VREF |
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Min. TOFF |
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Q |
TRIG |
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+ |
OV |
Latch |
1-SHOT |
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VDDP |
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115% VREF |
S1 |
Q |
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DRV |
LGATE |
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- |
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Latch |
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FB |
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- |
UV |
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PGND |
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70% VREF |
S1 |
Q |
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Diode |
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+ |
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- |
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Emulation |
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90% VREF |
+ |
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20uA |
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SS Timer |
Thermal |
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VDD |
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+ |
OC |
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Shutdown |
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GND |
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- |
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EN/DEM |
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PGOOD |
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Copyright ©2014 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
www.richtek.com |
DS8202/A/B-07 April 2014 |
4 |
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RT8202/A/B |
Absolute Maximum Ratings (Note 1) |
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Input Voltage, TON to GND ---------------------------------------------------------------------------------------------- |
−0.3V to 32V |
BOOT to GND -------------------------------------------------------------------------------------------------------------- |
−0.3V to 38V |
PHASE to BOOT ---------------------------------------------------------------------------------------------------------- |
−6V to 0.3V |
VDD, VDDP, VOUT, EN/DEM, FB, PGOOD to GND -------------------------------------------------------------- |
−0.3V to 6V |
UGATE to PHASE -------------------------------------------------------------------------------------------------------- |
−0.3V to 6V |
OC to GND ------------------------------------------------------------------------------------------------------------------ |
−0.3V to 32V |
LGATE to GND ------------------------------------------------------------------------------------------------------------- |
−0.3V to 6V |
PGND to GND -------------------------------------------------------------------------------------------------------------- |
−0.3V to 0.3V |
Power Dissipation, PD @ TA = 25°C |
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WQFN-16L 4x4 ------------------------------------------------------------------------------------------------------------ |
1.852W |
WQFN-16L 3x3 ------------------------------------------------------------------------------------------------------------ |
1.471W |
WQFN-14L 3.5x3.5 ------------------------------------------------------------------------------------------------------- |
1.667W |
Package Thermal Resistance (Note 2) |
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WQFN-16L 4x4, θJA ------------------------------------------------------------------------------------------------------- |
54°C/W |
WQFN-16L 4x4, θJC ------------------------------------------------------------------------------------------------------ |
7°C/W |
WQFN-16L 3x3, θJA ------------------------------------------------------------------------------------------------------- |
68°C/W |
WQFN-16L 3x3, θJC ------------------------------------------------------------------------------------------------------ |
7.5°C/W |
WQFN-14L 3.5x3.5, θJA -------------------------------------------------------------------------------------------------- |
60°C/W |
WQFN-14L 3.5x3.5, θJC ------------------------------------------------------------------------------------------------- |
7°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) |
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HBM (Human Body Mode) ---------------------------------------------------------------------------------------------- |
2kV |
MM (Machine Mode) ------------------------------------------------------------------------------------------------------ |
200V |
Recommended Operating Conditions |
(Note 4) |
Input Voltage, VIN ---------------------------------------------------------------------------------------------------------- |
4.5V to 26V |
Supply Voltage, VDD, VDDP ---------------------------------------------------------------------------------------------- |
4.5V to 5.5V |
Junction Temperature Range -------------------------------------------------------------------------------------------- |
−40°C to 125°C |
Ambient Temperature Range -------------------------------------------------------------------------------------------- |
−40°C to 85°C |
Electrical Characteristics
(VDD = VDDP = 5V, VIN = 15V, VOUT = 1.25V, EN/DEM = VDD, RTON = 1MΩ, TA = 25°C, unless otherwise specified)
Parameter |
Symbol |
Test Conditions |
Min |
Typ |
Max |
Unit |
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PWM Controller |
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Quiescent Supply Current |
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VDD + VDDP, FB = 0.8V |
-- |
-- |
1250 |
A |
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TON Operating Current |
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RTON = 1M |
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-- |
15 |
-- |
A |
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VDD + VDDP |
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-- |
1 |
10 |
A |
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Shutdown Current |
ISHDN |
TON |
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-- |
1 |
5 |
A |
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EN/DEM = 0V |
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10 |
1 |
-- |
A |
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Copyright ©2014 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
DS8202/A/B-07 April 2014 |
www.richtek.com |
|
5 |
RT8202/A/B
Parameter |
Symbol |
Test Conditions |
Min |
Typ |
Max |
Unit |
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FB Reference Voltage |
VFB |
VDD = 4.5 to 5.5V |
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0.742 |
0.75 |
0.758 |
V |
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FB Input Bias Current |
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FB = 0.75V |
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1 |
0.1 |
1 |
A |
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Output Voltage Range |
VOUT |
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0.75 |
-- |
3.3 |
V |
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On-Time |
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VIN = 15V, VOUT = 1.25V, RTON = 1M |
267 |
334 |
401 |
ns |
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Minimum Off-Time |
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250 |
400 |
550 |
ns |
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VOUT Shutdown Discharge |
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EN/DEM = GND |
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-- |
20 |
-- |
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Resistance |
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Current Sensing |
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ILIM Source Current |
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LGATE = High |
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18 |
20 |
22 |
A |
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Current Comparator Offset |
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GND OC |
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10 |
-- |
10 |
mV |
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Current Limit Setting Range |
RILIM |
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2.5 |
-- |
10 |
k |
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Zero Crossing Threshold |
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GND PHASE, EN/DEM = 5V |
10 |
-- |
5 |
mV |
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Fault Protection |
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Current Limit Sense |
VRILIM |
GND PHASE, RILIM = 2.5k |
35 |
50 |
65 |
mV |
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Voltage |
GND PHASE, RILIM = 10k |
170 |
200 |
230 |
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Output UV Threshold |
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60 |
70 |
80 |
% |
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OVP Threshold |
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With respect to error comparator |
10 |
15 |
20 |
% |
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threshold |
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OV Fault Delay |
|
FB forced above OV threshold |
-- |
20 |
-- |
s |
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VDD UVLO Threshold |
|
Rising edge, Hysteresis = 20mV, |
4.1 |
4.3 |
4.5 |
V |
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PWM disabled below this level |
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Soft-Start Ramp Time |
|
From EN high to internal VREF reach |
-- |
1.35 |
-- |
ms |
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0.71V (095%) |
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UV Blank Time |
|
From EN signal going high |
-- |
3.1 |
-- |
ms |
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Thermal Shutdown |
|
|
|
-- |
155 |
-- |
°C |
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Thermal Shutdown |
|
|
|
-- |
10 |
-- |
°C |
|
Hysteresis |
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Driver On-Resistance |
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UGATE Driver Pull Up |
|
BOOT PHASE = 5V |
|
-- |
1.5 |
5 |
|
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|
UGATE Driver Sink |
RUGATEsk |
BOOT PHASE = 5V |
|
-- |
1.5 |
5 |
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LGATE Driver Pull Up |
|
LGATE, High State (Source) |
-- |
1.5 |
5 |
|
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|
|
|
|
|
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LGATE Driver Pull Down |
|
LGATE, Low State (Sink) |
-- |
0.6 |
2.5 |
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UGATE Driver Source/Sink |
|
UGATE PHASE = 2.5V, |
-- |
1 |
-- |
A |
||
Current |
|
BOOT PHASE = 5V |
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LGATE Driver Source |
|
LGATE forced to 2.5V |
|
-- |
1 |
-- |
A |
|
Current |
|
|
||||||
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||
LGATE Driver Sink Current |
|
LGATE forced to 2.5V |
|
-- |
3 |
-- |
A |
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Dead Time |
|
LGATE Rising (PHASE = 1.5V) |
-- |
30 |
-- |
ns |
||
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|
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|||
|
UGATE Rising |
|
-- |
30 |
-- |
|||
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Copyright ©2014 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
www.richtek.com |
DS8202/A/B-07 April 2014 |
6 |
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