TNY263_04 POWERINT [Power Integrations, Inc.], TNY263_04 Datasheet - Page 7

• Manufacturer Part Number: TNY263_04
• Description: Enhanced, Energy Efficient, Low Power Off-line Switcher
• Manufacturer: POWERINT [Power Integrations, Inc.]

Figure 14. 2.5 W Constant Voltage, Constant Current Battery Charger with Universal Input (85-265 VAC).
The external resistor (2 MΩ) is connected to the EN/UV pin in
this case to prevent unwanted restarts.
The TinySwitch-II does not require a bias winding to provide
power to the chip, because it draws the power directly from the
DRAIN pin (see Functional Description above). This has two
main benefits. First, for a nominal application, this eliminates
the cost of a bias winding and associated components.
Secondly, for battery charger applications, the current-voltage
characteristic often allows the output voltage to fall close to
zero volts while still delivering power. This type of application
normally requires a forward-bias winding which has many
more associated components. With TinySwitch-II, neither are
necessary. For applications that require a very low no-load
power consumption (50 mW), a resistor from a bias winding to
the BYPASS pin can provide the power to the chip. The
minimum recommended current supplied is 750 µA. The
BYPASS pin in this case will be clamped at 6.3 V. This method
will eliminate the power draw from the DRAIN pin, thereby
reducing the no-load power consumption and improving full-
load efficiency.
Current Limit Operation
Each switching cycle is terminated when the DRAIN current
reaches the current limit of the TinySwitch-II. Current limit
operation provides good line ripple rejection and relatively
constant power delivery independent of input voltage.
85-265
VAC
1N4005
1N4005
Fusible
8.2 Ω
RF1
D1
D3
1N4005
1N4005
D2
D4
3.3 µF
400 V
C1
2.2 mH
1.2 kΩ
R1
L1
200 kΩ
3.3 µF
R2
400 V
TinySwitch-II
C2
1N4937
TNY264
D6
U1
C3
2.2 nF
D
S
EN/UV
BP
0.1 µF
C3
1
C8 680 pF
4
Y1 Safety
BYPASS Pin Capacitor
The BYPASS pin uses a small 0.1 µF ceramic capacitor for
decoupling the internal power supply of the TinySwitch-II.
Application Examples
The TinySwitch-II is ideal for low cost, high efficiency power
supplies in a wide range of applications such as cellular phone
chargers, PC standby, TV standby, AC adapters, motor control,
appliance control and ISDN or a DSL network termination. The
132 kHz operation allows the use of a low cost EE13 or EF12.6
core transformer while still providing good efficiency. The
frequency jitter in TinySwitch-II makes it possible to use a
single inductor (or two small resistors for under 3 W applications
if lower efficiency is acceptable) in conjunction with two input
capacitors for input EMI filtering. The auto-restart function
removes the need to oversize the output diode for short circuit
conditions allowing the design to be optimized for low cost and
maximum efficiency. In charger applications, it eliminates the
need for a second optocoupler and Zener diode for open loop
fault protection. Auto-restart also saves the cost of adding a fuse
or increasing the power rating of the current sense resistors to
survive reverse battery conditions. For applications requiring
under-voltage lock out (UVLO), such as PC standby, the
TinySwitch-II eliminates several components and saves cost.
TinySwitch-II is well suited for applications that require
constant voltage and constant current output. As TinySwitch-II
T1
LTV817
U2
8
5
1N5819
Shield
2N3904
D5
Q1
10 µF
10 V
47 Ω
C7
R9
1/2 W
1.2 Ω
22 Ω
330 µF
R4
R3
16 V
C5
100 Ω
R7
1/2 W
1 Ω
R6
270 Ω
BZX79-
B3V9
100 µF
R8
3.9 V
VR1
TNY263-268
35 V
C6
PI-2706-040903
4/04
500 mA
E
RTN
+ 5 V
7