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PDF RT4805 Data sheet ( Hoja de datos )
| Número de pieza | RT4805 | |
| Descripción | Synchronous Boost Regulator | |
| Fabricantes | Richtek Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de RT4805 (archivo pdf) en la parte inferior de esta página. Total 22 Páginas | ||
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RT4805
2.5MHz, Synchronous Boost Regulator with Bypass Mode
General Description
The RT4805 allows systems to take advantage of new
battery chemistries that can supply significant energy
when the battery voltage is lower than the required
voltage for system power ICs. By combining built-in
power transistors, synchronous rectification, and low
supply current; this IC provides a compact solution for
systems using advanced Li-Ion battery chemistries.
The RT4805 is a boost regulator designed to provide a
minimum output voltage from a single-cell Li-Ion battery,
even when the battery voltage is below system
minimum. In boost mode, output voltage regulation is
guaranteed to a maximum load current of 2A.
Quiescent current in Shutdown Mode is less than 1A,
which maximizes battery life. The regulator transitions
smoothly between Bypass and normal Boost Mode.
The device can be forced into Bypass Mode to reduce
quiescent current.
The RT4805 is available in the WL-CSP-16B 1.67x1.67
(BSC) package.
Features
4 Few External Components: 0.47H Inductor
and 0603 Case Size Input and Output Capacitors
Input Voltage Range: 1.8V to 5V
Output Range from 2.85V to 4.4V
VSEL = L 3.2V
VSEL = H 3.4V
Maximum Continuous Load Current: 2A at VIN >
2.65V Boosting VOUT to 3.35V
Up to 96% Efficient
True Bypass Operation when VIN > Target VOUT
Internal Synchronous Rectifier
True Load Disconnect when Shut Down
Forced Bypass Mode
VSEL Control to Optimize Target VOUT
Short-Circuit Protection
I2C Controlled Interface
Ultra low Operating Quiescent Current
Small WL-CSP 16B Package
Applications
Single-Cell Li-Ion, LiFePO4 Smart-Phones or Tablet
2.5G/3G/4G Mini-Module Data Cards
Simplified Application Circuit
+ CIN
-
L1
RT4805
VIN VOUT
LX
VSEL
EN
nBYP
SDA
SCL
PGOOD
AGND PGND
COUT
To pull high voltage
Copyright © 2015 Richtek Technology Corporation. All rights reserved.
DS4805-00 November 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1
1 page  
VOUT
Q3
Q1
VIN LX
Q2
GND
Figure 2. Boost Converter With Bypass Mode
VOUT
VIN
Figure 3. RT4805 mode changed
Force Pass-Through Mode
When EN pulled high and nBYP pulled low. The device
is active in the Force pass-through mode. It supplies
current is approximately 15A typ. From the battery,
the device is short circuit protected by a current limit of
4000mA.
VSEL
It is concerned the minimum output voltage at the
heavy load condition. There are two output voltage
levels (3.2V & 3.4V) in Boost mode and Bypass mode.
It can be selected by VSET, so it must not be floating.
RT4805
PGOOD (Power Good)
Power good is a open-drain input. If it is 0, it stands for
fault occurred. The power good provide the information
to show the state of the system,
PGOOD pin show high when the sequence of
soft-start is completed.
Any fault cause PGOOD to be pulled low.
PGOOD low when PMOS current limit has triggered
for OR the die the temperature exceeds 120C.
PGOOD is re-asserted when the device cools below
to 100C.
OCP
The converter senses the current signal when the
high-side P-MOSFET turns on. As a result, the OCP is
cycle by-cycle current limitation. If the OCP occurs, the
converter holds off the next on pulse until inductor
current drops below the OCP limit.
OTP
The converter has an over-temperature protection.
When the junction temperature is higher than the
thermal shutdown rising threshold, the system will be
latched and the output voltage will no longer be
regulated until the junction temperature drops under the
falling threshold.
EN & nBYP
It is used to select mode. As the table 1 shown, there
are four device states. When EN and nBYP both pull
high, RT4805 is normal operation and enter automatic
mode.
If the EN pull low, and nBYP pull high/low, RT4805 is
forced in shut-down mode and the quiescent is less
than 1A. It works in force pass-through mode, if the
EN set high and nBYP set low.
Copyright © 2015 Richtek Technology Corporation. All rights reserved.
DS4805-00 November 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
5
5 Page 
70
60
50
40
30
20
10
0
0
Output Ripple vs. Load Current
VOUT = 3.4V, ILOAD = 0A to 2A
VIN = 2.5V
VIN = 2.7V
VIN = 3V
VIN = 3.3V
500
1000
1500
Load Current (mA)
2000
Maximum Load Current vs. Input Voltage
5.0
4.0
3.0
2.0
1.0
VIN = 2.5V to 3.7V, VOUT = 3.4V
0.0
2.5 2.7 2.9 3.1 3.3 3.5 3.7
Input Voltage (V)
VOUT
(2V/Div)
ILX
(1A/Div)
EN
(5V/Div)
PGOOD
(5V/Div)
Startup
VIN = 3V, VOUT = 3.2V, Load = 50
Time (100s/Div)
RT4805
70
60
50
40
30
20
10
0
0
Output Ripple vs. Load Current
VOUT = 3.2V, ILOAD = 0A to 2A
VIN = 2.5V
VIN = 2.7V
VIN = 3V
VIN = 3.1V
500
1000
1500
Load Current (mA)
2000
Startup
VOUT
(2V/Div)
ILX
(1A/Div)
EN
(5V/Div)
PGOOD
(5V/Div)
VOUT
(2V/Div)
VIN = 3V, VOUT = 3.4V, Load = 50
Time (100s/Div)
Overload Protection
VIN = 3V, VOUT = 3.4V
ILX
(2A/Div)
PGOOD
(5V/Div)
Time (1ms/Div)
Copyright © 2015 Richtek Technology Corporation. All rights reserved.
DS4805-00 November 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
11
11 Page | ||
| Páginas | Total 22 Páginas | |
| PDF Descargar | [ Datasheet RT4805.PDF ] | |
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