Buck Controller. RT8208E Datasheet


RT8208E Controller. Datasheet pdf. Equivalent


Part Number

RT8208E

Description

Programmable Output Voltage Single Synchronous Buck Controller

Manufacture

Richtek

Total Page 18 Pages
Datasheet
Download RT8208E Datasheet


RT8208E
RT8208E/F
Programmable Output Voltage Single Synchronous
Buck Controller
General Description
The RT8208E/F is a constant-on-time PWM controller
which provides four resistor programmable DC output
voltages by controlling the G0 and G1 digital input. The
output voltage is programmable from 0.75V to 3.3V. The
RT8208E/F offers the lowest total solution cost in systems
where need output voltage slewing. The RT8208E/F
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-
onresponse to load transient while maintaining a
relatively constant frequency. It provides the high efficiency,
excellent transient response, and DC output accuracy
needed for stepping down high voltage batteries to
generate low voltage CPU core, graphics, I/O and chipset
RAM supplies in notebook computers.
The RT8208E/F achieves high efficiency at a reduced cost
by eliminating the current sense resistor 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 from high voltage batteries for the highest
possible efficiency. Additional features include soft-start,
under voltage protection, programmable over current
protection and non-overlapping gate drive. The RT8208E/
F is available in a WQFN-16L 3x3 package.
Pin Configurations
(TOP VIEW)
16 15 14 13
VOUT
VDD
FB
PGOOD
1
2
3
4
GND
17
12 UGATE
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
* Patent Pending
Applications
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)
Turn-on D0/D1 MOSFET
E : G0/G1 Active-High
F : G0/G1 Active-Low
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.
DS8208E/F-03 May 2011
www.richtek.com
1

RT8208E
RT8208E/F
Marking Information
RT8208EGQW
30= : Product Code
30=YM
DNN
YMDNN : Date Code
RT8208EZQW
30 YM
DNN
30 : Product Code
YMDNN : Date Code
RT8208FGQW
31=YM
DNN
31= : Product Code
YMDNN : Date Code
RT8208FZQW
31 YM
DNN
31 : Product Code
YMDNN : Date Code
Typical Application Circuit
R3
250k
VIN
4.5V to 26V
VDDP
PGOOD
RT8208E/F
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 G1
D1 5
D0 6
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.
1
2
3
4
5
6
7
Pin Name
Pin Function
VOUT
Output Voltage Pin. Connect to the output of PWM converter. VOUT is an input of the
PWM controller.
VDD
Analog supply voltage input for the internal analog integrated circuit. Bypass to GND with
a 1μF ceramic capacitor.
FB
Feedback Input Pin. Connect FB to a resistor voltage divider from VOUT to GND to adjust
output voltage from 0.75V to 3.3V
PGOOD
Power good signal open-drain output of PWM converter. This pin will be pulled 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.
G0
Control Input Pin for the D0 MOSFET. A logic active-high for RT8208E and active-low for
RT8208F to turn on the internal MOSFET at D0.
www.richtek.com
2
To be continued
DS8208E/F-03 May 2011


Features RT8208E/F Programmable Output Voltage S ingle Synchronous Buck Controller Gene ral Description The RT8208E/F is a cons tant-on-time PWM controller which provi des four resistor programmable DC outpu t voltages by controlling the G0 and G1 digital input. The output voltage is p rogrammable from 0.75V to 3.3V. The RT8 208E/F offers the lowest total solution cost in systems where need output volt age slewing. The RT8208E/F provides an automatic masking power good output dur ing output voltage transition. The cons tant-on-time PWM control scheme handles wide input/output ratios with ease and provides 100ns “instanton” respons e to load transient while maintaining a relatively constant frequency. It prov ides the high efficiency, excellent tra nsient response, and DC output accuracy needed for stepping down high voltage batteries to generate low voltage CPU c ore, graphics, I/O and chipset RAM supp lies in notebook computers. The RT8208E /F achieves high efficiency at a reduced cost by eliminating the cu.
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