®
RT8525
Boost Controller with Dimming Control
General Description
The RT8525 is a wide input operating voltage range step
up controller. High voltage output and large output current
are feasible by using an external N-MOSFET. The RT8525
input operating range is from 4.5V to 29V.
The RT8525 is an optimized design for wide output voltage
range applications. The output voltage of the RT8525 can
be adjusted by the FB pin. The PWMI pin can be used as
a digital input, allowing WLED brightness control with a
logic-level PWM signal.
Features
VIN Range : 4.5V to 29V
Programmable Soft-Start Time
Programmable Boost SW Frequency from 50kHz to
600kHz
Output Over Voltage Protection
Output Under Voltage Protection
14-Lead SOP Package
RoHS Compliant and Halogen Free
Applications
LCD TV, Monitor Display Backlight
LED Driver Application
Ordering Information
RT8525
Package Type
S : SOP-14
Lead Plating System
G : Green (Halogen Free and Pb Free)
Pin Configurations
(TOP VIEW)
VDC
VIN
COMP
SS
FSW
AGND
PWMI
14
2
3
4
5
6
7
13
12
11
10
9
8
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.
DRV
PGND
EN
ISW
OOVP
FB
FAULT
Marking Information
RT8525GS : Product Number
SOP-14
RT8525
GSYMDNN
YMDNN : Date Code
Typical Application Circuit
V
IN
24V
C
IN
100µF
C
VIN
1µF
L1
33µH
RT8525
14
2 VIN
DRV
D1
1
VDC
C
DC
1µF
3 COMP
5 FSW
4 SS
ISW
R
SLP
11 2.4k
M1
C
OUT
100µF x 2
V
OUT
50V
R
C
33k
C
C1
27nF
C
C2
PGND
13
R
S
50m
R
SW
56k
C
SS
0.33µF
R
FLT
8 100k
FAULT
OOVP 10
AGND 6
FB 9
7
PWMI
R
FB1
117k
R
FB2
3k
PWMI
12V
C
OVP
R
OVP1
150k
R
OVP2
6k
Chip Enable
12 EN
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8525-01 March 2012
www.richtek.com
1
RT8525
Functional Pin Description
Pin No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Pin Name
VDC
VIN
COMP
SS
FSW
AGND
PWMI
FAULT
FB
OOVP
ISW
EN
PGND
DRV
Output of Internal Pre-Regulator.
IC Power Supply.
Compensation for Error Amplifier. Connect a compensation network to ground.
External Capacitor to Adjust Soft-Start Time.
Frequency Adjust Pin. This pin allows setting the switching frequency with a resistor
from 50kHz to 600kHz.
Analog Ground.
External Digital Input for Dimming Function.
Open Drain Output for Fault Detection.
Feedback to Error Amplifier Input.
Sense Output Voltage for Over Voltage Protection and Under Voltage Protection.
External MOSFET Switch Current Sense Pin. Connect the current sense resistor
between the external N-MOSFET switch and ground.
Chip Enable (Active High).
Power Ground of Boost Controller.
Drive Output for the N-MOSFET.
Pin Function
Function Block Diagram
FSW
VIN
VDC
UVLO
12V LDO
OTP
+
0.1V
OOVP
2.5V
DRV
OOVP/OUVP
Logic
-
+
-
FAULT
FAULT
Protection
OSC
S
R
+
OC
-
Q
Q
EN
PWMI
PGND
AGND
PWM
Controller
0.4V
V
OS
Blanking
+
EA
-
ISW
+
-
-
+
-
1.25V
FB
COMP
SS
4µA
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS8525-01 March 2012
RT8525
Absolute Maximum Ratings
(Note 1)
−0.3V
to 32V
−0.3V
to 13.2V
−0.3V
to 6V
1.000W
100°C/W
VIN to GND ------------------------------------------------------------------------------------------------------------------
VDC, DRV, FAULT to GND -----------------------------------------------------------------------------------------------
EN, COMP, SS, FSW, FB, OOVP, ISW, PWMI to GND ---------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
SOP-14 ----------------------------------------------------------------------------------------------------------------------
Package Thermal Resistance (Note 2)
SOP-14 ,
θ
JA
----------------------------------------------------------------------------------------------------------------
Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------- 260°C
Junction Temperature ----------------------------------------------------------------------------------------------------- 150°C
Storage Temperature Range --------------------------------------------------------------------------------------------
−65°C
to 150°C
ESD Susceptibility (Note 3)
HBM -------------------------------------------------------------------------------------------------------------------------- 2kV
MM ---------------------------------------------------------------------------------------------------------------------------- 200V
Recommended Operating Conditions
(Note 4)
Supply Input Voltage, VIN ----------------------------------------------------------------------------------------------- 4.5V to 29V
Junction Temperature Range --------------------------------------------------------------------------------------------
−40°C
to 125°C
Ambient Temperature Range --------------------------------------------------------------------------------------------
−40°C
to 85°C
Electrical Characteristics
(V
IN
= 21V, V
OUT
= 50V, T
A
= 25°C, unless otherwise specified)
Parameter
Input Power Supply
Quiescent Current
Shutdown Current
Under Voltage Lockout
Threshold
Under Voltage Lockout
Hysteresis
12V Regulator
Regulator Output Voltage
Dropout Voltage
Short-Circuit Current Limit
Control Input
EN Threshold
Voltage
EN Sink Current
Sleeping
Mode
Shutdown Delay
Shutdown
Mode
Symbol
I
Q
I
SHDN
V
UVLO
ΔV
UVLO
Test Conditions
No Switching, R
SW
= 56kΩ
V
EN
= 0V
V
IN
Rising
Min
--
--
--
--
Typ
1.3
10
3.8
500
Max Unit
2
--
--
--
mA
μA
V
mV
V
DC
V
DROP
I
SC
13.5V < V
IN
< 16V, 1mA < I
LOAD
< 100mA
16V < V
IN
< 20V, 1mA < I
LOAD
< 50mA
20V < V
IN
< 29V, 1mA < I
LOAD
< 20mA
V
IN
−
V
DC
, V
IN
= 12V, I
LOAD
= 100mA
V
DC
Short to GND
11.4
--
--
2
--
12
500
270
--
--
5
--
--
12.6
--
--
--
0.8
--
--
--
V
mV
mA
Logic-High V
IH
Logic-Low
V
IL
I
IH
t
SLEEP
t
SHDN
V
EN
= 5V
R
SW
= 56kΩ, EN = L, 12V Regular Shutdown
R
SW
= 56kΩ, EN = L, IC Shutdown
V
μA
ms
ms
--
55
110
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8525-01 March 2012
www.richtek.com
3
RT8525
Parameter
Boost Controller
Switching Frequency
Minimum On-Time
Maximum Duty
Feedback Voltage
Slope Compensation
Peak Magnitude of Slope
Compensation Current
Soft-Start
Soft-Start Current
Gate Driver
DRV On-Resistance
Peak Sink Current
Peak Source Current
Rise Time
Fall Time
PWM Dimming Control
PWMI
Threshold
Voltage
Logic-High
Logic-Low
V
PWMI_H
V
PWMI_L
V
OCP
V
OVP
V
UVP
T
SD
ΔT
SD
Including Slope Compensation Magnitude
2
--
--
2.375
--
--
--
--
--
0.4
2.5
0.1
150
50
--
0.8
--
2.625
--
--
--
V
R
DS(ON)_N
R
DS(ON)_P
I
PEAKsk
I
PEAKsr
t
r
t
f
I
SINK
= 100mA (N-MOSFET)
I
SOURCE
= 100mA (P-MOSFET)
C
LOAD
= 1nF
C
LOAD
= 1nF
C
LOAD
= 1nF
C
LOAD
= 1nF
--
--
--
--
--
--
1
1.5
2.2
2.55
6
5
--
--
--
--
--
--
Ω
Ω
A
A
ns
ns
I
SLOPE, PK
--
50
--
μA
f
SW
t
MON
D
MAX
V
FB
Switching
R
SW
= 56kΩ
--
--
90
1.225
200
250
--
1.25
--
--
--
1.275
kHz
ns
%
V
Symbol
Test Conditions
Min
Typ
Max
Unit
I
SS
3
4
5
μA
Protection Function
OCP Threshold
V
OUT
OVP Threshold
V
OUT
UVP Threshold
Thermal Shutdown
Temperature
Thermal Shutdown
Hysteresis
V
V
V
°C
°C
Note 1.
Stresses beyond those listed
“Absolute
Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in
the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may
affect device reliability.
Note 2.
θ
JA
is measured at T
A
= 25°C on a low effective thermal conductivity single-layer test board per JEDEC 51-3.
Note 3.
Devices are ESD sensitive. Handling precaution is recommended.
Note 4.
The device is not guaranteed to function outside its operating conditions..
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS8525-01 March 2012
RT8525
Typical Operating Characteristics
Quiescent Current vs. Input Voltage
3.0
3.0
Quiescent Current vs. Temperature
Quiescent Current (mA)
Quiescent Current (mA)
No Switching
2.5
2.0
1.5
1.0
0.5
0.0
4
9
14
19
24
29
2.5
2.0
1.5
1.0
0.5
0.0
-50
-25
0
25
50
No Switching
75
100
125
Input Voltage (V)
Temperature (°C)
Feedback Voltage vs. Input Voltage
1.5
1.5
Feedback Voltage vs. Temperature
1.3
Feedback Voltage (V)
4
9
14
19
24
29
Feedback Voltage (V)
1.4
1.4
1.3
1.2
1.2
1.1
1.1
1.0
1.0
-50
-25
0
25
50
75
100
125
Input Voltage (V)
Temperature (°C)
Switching Frequency vs. Temperature
300
100
Boost Efficiency vs. Load Current
Switching Frequency (kHz)
1
260
90
220
Efficiency(%)
R
SW
= 56kΩ
80
180
70
140
60
V
IN
= 24V, V
OUT
= 50V
50
0
0.4
0.8
1.2
1.6
2
100
-50
-25
0
25
50
75
100
125
Temperature (°C)
Load Current (A)
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8525-01 March 2012
www.richtek.com
5
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