Buck Controller. RT8208A Datasheet


RT8208A Controller. Datasheet pdf. Equivalent


Part Number

RT8208A

Description

Programmable Output Voltage Single Synchronous Buck Controller

Manufacture

Richtek

Total Page 18 Pages
Datasheet
Download RT8208A Datasheet


RT8208A
RT8208A/B
Programmable Output V oltage Single Synchronous
Buck Controller
General D escription
The RT8208A/B is a con stant-on-time PWM controller
which provide s f our re sistor programmable DC output
voltages by controlling the G0 and G1 digital input. The
output voltage is programmable from 0.75V to 3.3V. The
RT8208A/B offers the lowest total solution cost in systems
where need output voltage slewing. The RT8208A/B
provides an automatic masking power good output during
output voltage transition.
The constant-on-time PWM control scheme handles wide
input/output ratios with ease and provides 100ns instant-
onrespon se to loa d tra nsient while maintaining a
relatively constant frequency. It provides the high efficiency,
excellent tra nsient respon se, a nd DC output a ccuracy
needed for stepping down high voltage batteries to
generate low voltage CPU core, graphics, I/O and chipset
RAM supplies in notebook computers.
The RT8208A/B achieves high efficiency at a reduced cost
by eliminating the current sense resistor in traditional
current mode PWMs. Efficiency is further enha nced by
its ability to drive very large synchronous rectifier
MOSFETs. The buck conversion allows this device to
directly step down from high voltage batteries for the highest
possible efficiency. Additional features include soft-start,
under voltage prote ction, programmable over current
protection and non-overlapping gate drive.The RT8208A/
B is available in a WQFN-16L 3x3 package.
Pin Configuration s
(TOP VIEW)
16 15 14 13
VO UT
VD D
FB
PGOOD
1
2
3
4
GND
17
12 UGAT E
11 PHASE
10 CS
9 VDDP
5 678
WQFN-16L 3x3
Features
z Ultra-High Efficiency
z Resistor Programmable Output Voltage from 0.75V
to 3.3V with Integrated Transition Support
z Quick Load Step Response within 100ns
z 1% VFB Accuracy over Line and Load
z 4.5V to 26V Battery Input Range
z Resistor Programmable Frequency
z Integrated Bootstrap Switch
z Resistor Programmable Positive Current Limit by
Low Side RDS(ON) Sense (Lossless Limit)
z Negative Current Limiter
z Voltage Transient Overshoot Eliminator*
z Over Voltage Protection
z Under Voltage Protection
z 4 Steps Current Limit During Soft-Start
z Power Good Indicator
z RoHS Compliant and Halogen Free
* Paten Pending
Application s
z Notebook Computers
z System Power Supplies
z I/O Supplies
z Programmable-Output Power Supplies
Ordering Information
RT8208
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 :
Turn-on D0/D1 MOSFET
A : G0/G1 High
B : G0/G1 Low
Richtek products are :
` RoHS compli ant and compatible with the current require-
ments of IPC/JEDEC J-ST D-020.
` Suitable for use in SnPb or Pb-free soldering processes.
DS8208A/B-04 May 2011
www.richtek.com
1
http://www.Datasheet4U.com

RT8208A
RT8208A/B
Marking Information
RT8208AGQW
FF= : Product Code
FF=YM
DNN
YMDNN : Date Code
RT8208AZQW
FF YM
DNN
FF : Product Code
YMDNN : Date Code
RT8208BGQW
FG=YM
DNN
FG= : Product Code
YMDNN : Date Code
RT8208BZQW
FG YM
DNN
FG : Product Code
YMDNN : Date Code
Typical Application Circuit
R3
250k
VIN
4.5V to 26V
VDDP
PGOOD
RT8208A/B
R4
16 TON
BOOT 13 0
R2
100k
9 VDDP
R1
10
C2
2 VDD
1µF
4 PGOOD
10 CS
R6
18k
CCM/DEM 15 EN/DEM
R5
UGATE 12 0
PHASE 11
LGATE 8 R10
0
G0 7 G0
FB 3
G1 14
D1 5
D0 6
G1
17 (Exposed Pad) GND
VOUT 1
C3
0.1µF
C4
10µF
Q1
BSC119N03S
L1
Q2
BSC119N03S
1µH
R7
C7
R11* R12*
R8 C5*
12k
R9
60k
VOUT = 0.9V
C6* C1
220µF
* : Optional
Functional Pin Description
Pin No.
1V
2
3
4P
5
6
Pin Name
Pin Function
OUT
VDD
FB
GOOD
Output Voltage Pin. Connect to the output of PWM converter. VOUT is an input of
the PWM controller.
Analog s upply voltage i nput for t he i nternal analog i ntegrated c ircuit. B ypass t o
GND with a 1μF ceramic capacitor.
Feedback Input Pin. Connect FB to a resistor voltage divider from VOUT to GND
to adjust output voltage from 0.75V to 3.3V
Power good s ignal open-drain output of P WM c onverter. This pi n w ill b e p ulled
high when the output voltage is within the target range.
D1 Drain of the internal MOSFET which is controlled by G1.
D0 Drain of the internal MOSFET which is controlled by G0.
www.richtek.com
2
To be continued
DS8208A/B-04 May 2011


Features RT8208A/B Programmable Output V oltage S ingle Synchronous Buck Controller Gener al D escription The RT8208A/B is a con stant-on-time PWM controller which prov ide s f our re sistor programmable DC o utput voltages by controlling the G0 an d G1 digital input. The output voltage is programmable from 0.75V to 3.3V. The RT8208A/B offers the lowest total solu tion cost in systems where need output voltage slewing. The RT8208A/B provides an automatic ma sking power good outpu t during output voltage transition. The constant-on-time PWM control sche me h andles wide input/output ratios with ea se and provides 100ns “ instanton” respon se to loa d tra nsient while ma intaining a relatively constant frequen cy. It provides the high ef ficiency, e xcellent tra nsient respon se, a nd DC output a ccuracy needed for stepping do wn high voltage batteries to generate l ow voltage CPU core, gra phics, I/O and chipset RAM supplies in notebook compu ters. The RT8208A/B achieves high efficiency at a reduced cost by e.
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