ETC BIT3102A

BIT3102A
Beyond Innovation Technology Co., Ltd.
Data Sheet
BIT3102A
Low Cost PWM CCFL Controller
Version: 1.3
Notice:
All information contained in this document is subject to change without notice.
No part of this document may be copied or reproduced in any form or by any means without
the prior written consent of Beyond Innovation Technology Co., Ltd.
03/02/27
Confidential
page 1 of 6
BIT3102A
Beyond Innovation Technology Co., Ltd.
Features:
Pin Layout:
PWM Modulation
Open Lamp Protection
Internal UVLO (Under Voltage Look Out) function
Dimming Control
CMOS Totem Pole output
NMOS output driving
SOP /DIP Packing
OUT
8
1
GND
VDD
RT
CMP
SST
VIN-
OLP
4
5
General Description:
Applications:
To aim at the Cold Cathode Fluorescent Lamp (CCFL)
applications, the BIT3102A integrated all functions
required in a single 8 pin chip. The chip provides a fully
functioned PWM control circuit with a true lamp current
feedback protection. By setting the required time for
striking the lamp through SST , the open-lamp condition
can be detected after lamp striking period. The lamp
dimming can be done through a PWM feedback loop.
CMOS process reduces the operating current (1mA
typical) and NMOS output driving capability enhances the
system efficiency.
Cold Cathode Fluorescent Lamps system
Notebook PC
LCD Monitor
Palm-top Computers
Video Phone/ Door Phone
Portable Instrumentation
Personal Digital Assistants
Airline Entertainment Centers
Automotive Display
ATM/ Financial Terminal
POS Terminal
Navigation Devices (GPS Equipment)
Test Equipment
Copiers and Office Equipment
Medical Equipment
Absolute Ratings: (if Ta=25℃)
VDD…………………………………-0.3 ~ +13.7 V
GND…………………………………±0.3 V
Input Voltage………………………..-0.3 ~ VDD+0.3 V
Operating Ambit Temperature…….0 ~ +70 ℃
Operating Junction Temperature….+150 ℃
Storage Temperature……………….-55~+150 ℃
Recommended Operating Condition:
Supply Voltage…………………………….4.5 ~ 13.2 V
Operating Frequency………………….….50K ~ 250K Hz
Operating Ambient Temperature………...0 ~ 70 ℃
Functional Block Diagram:
VDD= 4.5 ~ 13.2V
OUT
GND
1¡G1 Current Mirror
VDD
VDD
2.25V
UVLO
0.75V
4.0V
ISS
2.15V
VDD
3.8V
-
2.25V
Band Gap
Reference
0.75V
Error Amplifier
RT
1.5V
-
Ramp Wave
Generator
+
2.5V
+
+
+
-
325mV
-
Latch
03/02/27
SST
+
VDD
VDD
CMP
VIN-
Confidential
OLP
page 2 of 6
BIT3102A
Beyond Innovation Technology Co., Ltd.
Function Description:
VSST = ISSRSS (1-e-t/RssCss); (Fig.a)
Where ISS= VRT/RT ± 10%,and VRT =2.15V
The output is disabled to "low" level and open lamp
protection is disable while SST <0.325V. A ~ 180uA
current is flow into INN to set
the initial state. The PWM
BI3102 RT
controller is enable while
2.5V < SST < 0.325V.
The
open lamp protection circuit
SST
will be enable when
VSST > 2.5V (Fig.b)
The
required time for striking
Fig.a
RT
Rss
Css
1¡G1 Current Mirror
VDD
VDD
ISS
2.15V1.5V
+
-
RT
2V
Opan Lamp Enable
-
the lamp could be calculated as
bellow:
TSTRIKE = (RSSCSS)
ln((ISSRSS-0.325)/(ISSRSS-2.175)
)
TSTRIKE is decided by the
characteristic of lamp.
SST
+
UVLO: The Under-Voltage-Look-Out circuit turns the
output driver off when supplying voltage drops to a
specified low level.
Band Gap Reference: This circuit provides a accuracy
voltage reference which is very stable even though the
operating temperature is variable. Base on this
reference, a specified voltage can be generated which
is used by another circuit.
Ramp Wave Generator: This circuit generates a typical
140KHz ramp wave. (as RT =100 KΩ) The relation
between frequency and resistor RT is as the equation
below:
Freq. (KHz) = 14000/RT(KΩ)
PWM Controller: The pulse width modulation control
circuit includes a ramp wave generator, an error
amplifier and a comparator. These devices provide
the required active components for the PWM feedback
control application.
The Power On Initialization and Open Lamp
Protection: The current source ISS charges the external
resistor and capacitor during power on process. The
voltage drops on the SST pin will be increased as
2.5V
Fig.b
Table 1. Power On Initialization and Open Lamp Protection
SST < 0.325V
2.5V < SST < 0.325V
SST >2.5V
OUT
Disable to "Low"
Enable
Enable
OLP
Disable
Disable
Enable
VINInternally Forced to "High"
Externally Controlled
Externally Controlled
Pin Description:
Pin No.
1
2
3
4
Names
OUT
VDD
CMP
Vin-
5
OLP
6
7
8
SST
RT
GND
Description
PWM output, logic high active for driving NMOS device.
Supply voltage.
PWM controller input, the output of error amplifier.
PWM controller input, the inverting input of error amplifier.
A voltage sense input pin. If voltage level is less than 325 mV after a user defined period of
time, the chip will shut down the OUT and PWM circuits. A digital latch circuit latches this
result. The latch condition will be released if the power be turned off.
The timer for open lamp protection.
Operation frequency control.
Ground
DC/AC Characteristics:
Parameter
Test Conditions
Min.
Typ.(Limits)
Max.
Unit
1.455
1.5
1.545
V
2
20
mV
Reference Voltage
Output voltage
Measure VinVDD=12V, Ta=25°C
Line regulation
03/02/27
VDD=4.5 ~ 13.2 V
Confidential
page 3 of 6
BIT3102A
Beyond Innovation Technology Co., Ltd.
Under Voltage Look Out
Upper threshold voltage
Ta=25℃
Hysteresis
3.8
4
4.2
V
0.1
0.2
0.3
V
140
160
KHz
250
KHz
Ramp Wave Generator
Frequency
RT=100K Ω
120
Operating Frequency
note 1
50
Output peak
2.25
V
Output valley
0.75
V
Error Amplifier
note 1
Input voltage
0.75
2.25
V
Open loop gain
60
80
dB
Unit gain band width
1
1.5
MHz
2.15V/RT
uA
2.5
V
325
mV
50
mV
Open Lamp Enable
Output current
VDD=12V, Ta=25℃
Open lamp detection enable
Open Lamp Protection
Open lamp detection lower threshold
VDD=12V, Ta=25℃
Hysteresis
Output
CMOS output impedance
note 1
50
Ω
Rising Time
1000pF load,
110
ns
Falling Time
note 1
100
ns
Ta : ambient temperature.
Note 1: It is guaranteed by design not 100% tested.
Application Circuit:
CN2
A low cost 1~2 lamp design.
HV
LV
BIT3102A
CN1
VDD
BRIGHTNESS
GND
1
2
3
4
1
2
3
OUT GND
VDD
RT
CMP SST
VIN- OLP
8
7
6
5
VDD=4.5V~13.2V
BRIGHTNESS=DC 0~3.3V, 0V brightest dimming.
CN2 may connect 1~2 CCFLs
03/02/27
Confidential
page 4 of 6
BIT3102A
Beyond Innovation Technology Co., Ltd.
Order Information:
BIT3102A-SO
SOP type packing
Part number
Beyond Innovation Technology Co., Ltd.
BIT3102A-DP
DIP type packing
Part number
Beyond Innovation Technology Co., Ltd.
03/02/27
Confidential
page 5 of 6
BIT3102A
Beyond Innovation Technology Co., Ltd.
Package Information :
Unit: mm
SOP type :
DIP type :
03/02/27
Confidential
page 6 of 6