TSC TS1935BCX5RFG

Preliminary
TS1935B
1.9A / 1.2MHz Boost DC to Dc Converter
SOT-25
Pin Definition:
1. SW
2. Ground
3. FB
4. EN
5. Input
General Description
The TS1935B is a current mode step up converter intended for small, low power applications. The converter input
voltage ranging from 2.6V to 5.5V. The Output voltage can be set up to 27V. The frequency is 1.2MHz allows the
use of small external inductors and capacitors and provides fast transient response. Internal soft start results in
small inrush current and extends battery life. Internal power MOSFET with very low RDS (ON) provides high
efficiency. The TS1935B automatically transits from PWM to PFM during light load condition further increasing
efficiency. The converter also provides protection functions such as under-voltage lockout, current limit and
thermal shutdown.
Features
Application
●
2.6V to 5.5 V operating input voltage range
●
White LED Current Source
●
Adjustable output voltage range up to 27V
●
Digital Still Cameras
●
1.2MHz Fixed Switching Frequency
●
Portable Electronics
●
Internal soft-start function
●
PDA’s and Palm-Top Computers
●
Current limit and Thermal shutdown protection
●
Local Boost Regulator
●
Under voltage Lockout
●
≤ 1µA Shutdown Current
Ordering Information
Part No.
Package
Packing
SOT-25
3Kpcs / 7” Reel
TS1935BCX5 RFG
Note: “G” denotes for Halogen Free
Absolute Maximum Rating
Parameter
Symbol
Limit
Unit
Input Voltage
VIN
GND - 0.3 to GND + 6.5
V
VEN, VFB
GND - 0.3 to VCC + 0.3
V
VSW
30
EN, VFB Voltage
SW Voltage
Ambient Temperature Range
-40 to +85
-40 to +125
o
TA
Junction Temperature Range
TJ
V
o
C
C
o
Storage Temperature Range
TSTG
-40 to +150
Note: Stress above the listed absolute maximum rating may cause permanent damage to the device
C
Thermal Information
Parameter
Symbol
Maximum
ӨJC
Thermal Resistance* (Junction to Case)
110
o
C/W
Thermal Resistance* (Junction to Ambient)
ӨJA
250
Internal Power Dissipation
PD
(TJ-TA)/ӨJA
Maximum Junction Temperature
Tj
150
o
Lead Solder Temperature (260 C)
Note: ӨJA is measured with the PCB copper area of approximately 1 in2(Multi-layer).
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Unit
o
5
C/W
mW
o
C
S
Version: Preliminary
Preliminary
TS1935B
1.9A / 1.2MHz Boost DC to Dc Converter
Electrical Specifications (Ta = 25oC, VIN=5V, EN=VIN, IL=0A unless otherwise noted)
Characteristics
Input Voltage range
Symbol
Conditions
VCC
Under Voltage Lockout
UVLO
Rising
UVLO Hysteresis
Min
Typ
Max
Units
2.6
--
5.5
V
--
2.35
2.60
V
--
-130
--
mV
3
--
27
V
Step-Up Voltage Adjust Range
VOUT
Operating quiescent current
ICCQ
IOUT= 0mA, VFB =1.5V
--
150
250
µA
Shutdown current
ISD
VEN=0V
--
0.1
1
µA
Feedback Voltage
VFB
1.213
1.238
1.263
V
-100
0.01
+100
nA
--
0.2
--
%
-
0.2
--
%
FB Input Leakage Current
IFB-LKG
VFB = 1.3V
VIN = 2.5 to 5.5V
IOUT = 20mA
VIN = 5V
IOUT = 1mA to 400mA
Line Regulation
Load Regulation
Switching frequency
FOSC
900
1200
1500
KHz
Maximum Duty
DMAX
82
87
-
%
Duty=50%
--
1.9
--
A
VCC=3V, ISW =1A
--
650
-
VCC=5V, ISW =1A
--
500
--
VLX = 27V, VFB =1.5V
--
--
1
µA
N-channel MOSFET
current limit
ILIM
MOSFET on-resistance
(Note 1)
RDS(on)
mΩ
SW Leakage Current
ISWL
EN high-level input voltage
VIH
1.0
--
--
V
EN low-level input voltage
VIL
--
--
0.4
V
EN Hysteresis
hys
--
200
-
mV
--
0.01
0.1
µA
EN input leakage current
IEN-LKG
VEN=GND or VCC
Thermal Shutdown
TDS
--
150
--
Thermal Shutdown Hysteresis
Note 1: Guaranteed by design
TSH
--
35
--
°C
Pin Description
Pin Number
Pin Name
1
SW
2
GND
3
FB
4
EN
5
VCC
Description
Power Switch Output.
SW is the drain of the internal MOSFET switch. Connect the power inductor and
output rectifier to SW. SW can swing between GND and 27V.
Ground. Tie directly to ground plan.
Feedback Input.
FB voltage is 1.238V. Connect a resistor divider to FB.
Regulator On/Off Control Input.
A high input at EN turns on the converter, and a low input turns it off.
When not used, connect EN to the input source for automatic startup.
The EN pin cannot be left floating.
Input Supply Pin.
Must be locally bypassed.
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Version: Preliminary
Preliminary
TS1935B
1.9A / 1.2MHz Boost DC to Dc Converter
Block Diagram
EN
VCC
UVLO
Soft
Start
Thermal
Shutdown
Enable/
Disable
Summing
Comparator
Vref
1.238V
FB
SW
Control and
Driver Logic
Error
Amplifier
N-MOS
Oscillator
1.2MHz
GND
Current
Sense
Slope
Compensation
Application Circuit
VIN=5V
R4
1M
ON
C1
10uF
D1
B240A
L1
4.7uH
TS1935B
AX5511
U1
5 VCC
4
EN
SW
FB
C3
R2
470K
1
3
C2
R3
GND
2
OFF
VOUT=12V
R1
54K
4.7uF
1nF
R2
VOUT = 1.238V X (1 + ------- )
R1
R2 Suggest 390K~820K
VIN
2.6~3.6V
2.6~5.3V
2.6~5.5V
VOUT
5V
7V
7.5~27V
R3
120KΩ
82KΩ
0Ω
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Version: Preliminary
Preliminary
TS1935B
1.9A / 1.2MHz Boost DC to Dc Converter
Application Information
Setting the Output Voltage
Application circuit item shows the basic application circuit with AX5511 adjustable output version. The external
resistor sets the output voltage according to the following equation:
R2
VOUT = 1.238V × (1+
)
R1
For most applications, R2 is a suggested a value by 390K~820KΩ. Place the resistor-divider as close to the IC as
possible to reduce the noise sensitivity.
Under Voltage Lockout (UVLO)
To avoid mis-operation of the device at low input voltages an under voltage lockout is included that disables the
device, if the input voltage falls below (2.35V-130mV).
Input Capacitor Selection
The input capacitor reduces the surge current drawn from the input and switching noise from the device. The input
capacitor impedance at the switching frequency shall be less than input source impedance to prevent high
frequency switching current passing to the input. A low ESR input capacitor sized for maximum RMS current must
be used. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and
small temperature coefficients. A 10µF ceramic capacitor for most applications is sufficient. For a lower output
power requirement application, this value can be decreased.
Output Capacitor Selection
The output capacitor is required to keep the output voltage ripple small and to ensure regulation loop stability. The
output capacitor must have low impedance at the switching frequency. Ceramic capacitors with X5R or X7R
dielectrics are recommended due to their low ESR and high ripple current. A 4.7uF ceramic capacitors works for
most of the applications. Higher capacitor values can be used to improve the load transient response.
Layout Guide
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Version: Preliminary
Preliminary
TS1935B
1.9A / 1.2MHz Boost DC to Dc Converter
SOT-25 Mechanical Drawing
DIM
A+A1
B
C
D
E
E
H
L
Ө1
S1
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SOT-25 DIMENSION
MILLIMETERS
INCHES
MIN
MAX
MIN
MAX.
0.09
1.25
0.0354
0.0492
0.30
0.50
0.0118
0.0197
0.09
0.25
0.0035
0.0098
2.70
3.10
0.1063
0.1220
1.40
1.80
0.0551
0.0709
1.90 BSC
0.0748 BSC
2.40
3.00
0.09449 0.1181
0.35 BSC
0.0138 BSC
0º
10º
0º
10º
0.95 BSC
0.0374 BSC
Version: Preliminary
Preliminary
TS1935B
1.9A / 1.2MHz Boost DC to Dc Converter
Notice
Specifications of the products displayed herein are subject to change without notice. TSC or anyone on its behalf,
assumes no responsibility or liability for any errors or inaccuracies.
Information contained herein is intended to provide a product description only. No license, express or implied, to
any intellectual property rights is granted by this document. Except as provided in TSC’s terms and conditions of
sale for such products, TSC assumes no liability whatsoever, and disclaims any express or implied warranty,
relating to sale and/or use of TSC products including liability or warranties relating to fitness for a particular purpose,
merchantability, or infringement of any patent, copyright, or other intellectual property right.
The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications.
Customers using or selling these products for use in such applications do so at their own risk and agree to fully
indemnify TSC for any damages resulting from such improper use or sale.
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Version: Preliminary