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PDF RT8243B Data sheet ( Hoja de datos )
| Número de pieza | RT8243B | |
| Descripción | Main Power Supply Controller | |
| Fabricantes | Richtek | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de RT8243B (archivo pdf) en la parte inferior de esta página. Total 24 Páginas | ||
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®
RT8243A/B/C
High Efficiency, Main Power Supply Controller
for Notebook Computers
General Description
The RT8243A/B/C is a dual step down, Switch Mode Power
Supply (SMPS) controller which generates logic supply
voltages for battery powered systems. It includes two
Pulse Width Modulation (PWM) controllers adjustable
from 2V to 5.5V and also two fixed 5V/3.3V linear
regulators. One of the controllers (LDO5) provides
automatic switch over to the BYP1 input connected to
the main SMPS1 output for maximized efficiency. An
optional external charge pump can be monitored through
SECFB (RT8243B/C). Other features include on board
power up sequencing, a power good output, internal soft-
start, and a soft discharge output that prevents negative
voltage during shutdown.
A constant on-time PWM control scheme operates without
sense resistors and assures fast load transient response
while maintaining nearly constant switching frequency. To
eliminate noise in audio applications, an ultrasonic mode
is included, which maintains the switching frequency
above 25kHz. Moreover, a diode emulation mode
maximizes efficiency for light load applications. The
SMPS1/SMPS2 switching frequency can be adjustable
from 200kHz/233kHz to 400kHz/466kHz respectively.
The RT8243A/B/C is available in a WQFN-20L 3x3
package, and operates over an extended temperature range
from −40°C to 85°C.
Features
5.5V to 25V Input Voltage Range
2V to 5.5V Output Voltage Range
No Current Sense Resistor Needed
5V/3.3V Linear Regulators
4700ppm/°C RDS(ON) Current Sensing
Internal Current Limit Soft-Start and Soft Discharge
Output
Built In OVP/UVP/OCP
Selectable Operation Mode with Switcher Enable
Control (RT8243A)
SECFB Input Maintains Charge Pump Voltage
(RT8243B/C)
Power Good Indicator (RT8243B/C includes SECFB)
RoHS Compliant and Halogen Free
Applications
Notebook computers
System Power Supplies
3- and 4- Cell Li+ Battery-Powered Device
Ordering Information
RT8243A/B/C
Package Type
QW : WQFN-20L 3x3 (W-Type)
Lead Plating System
Z : ECO (Ecological Element with
Halogen Free and Pb free)
Pin Function With
A : ENM
B : SECFB
C : SECFB, Ultrasonic Mode
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.
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS8243A/B/C-07 November 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1
1 page  
RT8243A/B/C
Functional Pin Description
Pin No.
1
2
Pin Name
FB1
ENTRIP1
Pin Function
SMPS1 Feedback Input. Connect FB1 to a resistive voltage divider from SMPS1
output to GND for adjustable output from 2V to 5.5V.
Channel 1 Enable and Current Limit Setting Input. Connect resistor to GND to set
the threshold for Channel 1 synchronous RDS(ON) sense. The GND-PHASE1
current limit threshold is 1/10th the voltage seen at ENTRIP1 over a 0.5V to 3V
range. There is an internal 10A current source from LDO5 to ENTRIP1. Leave
ENTRIP1 floating or drive it above 4.5V to shut down channel 1.
3 TON
ON-Time/Frequency Adjustment Input. Connect to GND with 56k to 100k.
Channel 2 Enable and Current Limit Setting Input. Connect resistor to GND to set
the threshold for Channel 2 synchronous RDS(ON) sense. The GND-PHASE2
4
ENTRIP2
current limit threshold is 1/10th the voltage seen at ENTRIP2 over a 0.5V to 3V
range. There is an internal 10A current source from LDO5 to ENTRIP2. Leave
ENTRIP2 floating or drive it above 4.5V to shut down channel 2.
5 FB2
SMPS2 Feedback Input. Connect FB2 to a resistive voltage divider from SMPS2
output to GND for adjustable output from 2V to 5.5V.
Power Good Output for Channel 1 and Channel 2 (RT8243A).
6 PGOOD
Power Good Output for Channel 1, Channel 2 and SECFB (RT8243B/C).
7
BOOT2
Boost Flying Capacitor Connection for SMPS2. Connect to an external capacitor
according to the typical application circuits.
8
UGATE2
Upper Gate Driver Output for SMPS2. UGATE2 swings between PHASE2 and
BOOT2.
9
PHASE2
Switch Node for SMPS2. PHASE2 is the internal lower supply rail for the UGATE2
high side gate driver. PHASE2 is also the current sense input for the SMPS2.
10
LGATE2
Lower Gate Drive Output for SMSP2. LGATE2 swings between GND and LDO5.
11 VIN
Supply Input for LDO5.
Master Enable Input. LDO5/LDO3 is enabled if it is within logic high level and
12 ENLDO disabled if it is less than the logic low level. Leave ENLDO floating to default
enable LDO5/LDO3.
ENM
(RT8243A)
Mode Selection with Enable Input. Pull up to LDO5 (Ultrasonic mode) or LDO3
(DEM) to turn on both switch Channels. Short to GND for shutdown.
Change Pump Feedback Pin. The SECFB is used to monitor the optional external
charge pump. Connect a resistive divider from the change pump output to GND to
13
SECFB
(RT8243B/C)
detect the output. If SECFB drops below its feedback threshold, an ultrasonic
pulse occurs to refresh the charge pump driven by LGATE1 or LGATE2.
If SECFB drops below its UV threshold, the switcher channels stop working and
enter into discharge-mode. Pull up to LDO5 or LDO3 to disable SECFB UVP
function.
14 LDO5
5V Linear Regulator Output. LDO5 is the supply voltage for the low side MOSFET
driver and also the analog supply voltage for the device. Bypass a minimum 4.7F
ceramic capacitor to GND
15 LDO3
3.3V Linear Regulator Output. Bypass a minimum 4.7F ceramic capacitor to
GND.
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS8243A/B/C-07 November 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
5
5 Page 
Typical Operating Characteristics
VOUT1 Efficiency vs. Load Current
100
90
80
70
60
DEM
ASM
50
40
30
20
10
0
0.001
VIN = 8V, RTON = 100kΩ, VENTRIP1 = 1.5V
VENTRIP2 = 5V, ENLDO = 5V
0.01
0.1
1
Load Current (A)
10
VOUT1 Efficiency vs. Load Current
100
90
80
70 DEM
60 ASM
50
40
30
20
10
0
0.001
VIN = 20V, RTON = 100kΩ, VENTRIP1 = 1.5V
VENTRIP2 = 5V, ENLDO = 5V
0.01
0.1
1
Load Current (A)
10
VOUT2 Efficiency vs. Load Current
100
90
80
70
60
DEM
ASM
50
40
30
20
10
0
0.001
VIN = 12V, RTON = 100kΩ, VENTRIP1 = 5V,
VENTRIP2 = 1.5V, ENLDO = 5V
0.01 0.1
1
Load Current (A)
10
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS8243A/B/C-07 November 2014
RT8243A/B/C
VOUT1 Efficiency vs. Load Current
100
90
80
70
DEM
ASM
60
50
40
30
20
10
0
0.001
VIN = 12V, RTON = 100kΩ, VENTRIP1 = 1.5V
VENTRIP2 = 5V, ENLDO = 5V
0.01 0.1
1
Load Current (A)
10
VOUT2 Efficiency vs. Load Current
100
90
80
70 DEM
ASM
60
50
40
30
20
10
0
0.001
VIN = 8V, RTON = 100kΩ, VENTRIP1 = 5V,
VENTRIP2 = 1.5V, ENLDO = 5V
0.01 0.1
1
Load Current (A)
10
VOUT2 Efficiency vs. Load Current
100
90
80
70
DEM
60 ASM
50
40
30
20
10
0
0.001
VIN = 20V, RTON = 100kΩ, VENTRIP1 = 5V,
VENTRIP2 = 1.5V, ENLDO = 5V
0.01 0.1
1
Load Current (A)
10
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
11
11 Page | ||
| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet RT8243B.PDF ] | |
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