TEA1654T NXP Semiconductors, TEA1654T Datasheet - Page 10

• Manufacturer Part Number: TEA1654T
• Manufacturer: NXP Semiconductors

Specifications of TEA1654T

• Operating Temperature (max): 145C
• Operating Temperature (min): -20C
• Pin Count: 14
• Mounting: Surface Mount
• Package Type: SO
• Screening Level: Commercial
• Lead Free Status / Rohs Status: Compliant

Philips Semiconductors
LOCK input
Pin LOCK is a general purpose (high-impedance) input
pin, which can be used to switch off the IC. As soon as the
voltage on this pin is raised above 2.5 V, switching will stop
immediately. The voltage on the V
V
again until the latch function is reset. The latch is reset as
soon as the V
internal OVP and OTP will also trigger this latch (see
Fig.2).
The detection level of this input is related to the V
voltage in the following way: 0.5
An internal Zener diode clamp of 5.6 V will protect this pin
from excessive voltages. No internal filtering is done on
this input.
OverTemperature Protection (OTP)
An accurate temperature protection is provided in the
circuit. When the junction temperature exceeds the
thermal shutdown temperature, the IC will stop switching.
When V
recharged to the V
switching again. Subsequently, V
UVLO level, etc.
Operation only recommences when the V
below a level of approximately 4.5 V (practically when the
V
Soft start-up
To prevent transformer rattle during hiccup, the
transformer peak current is slowly increased by the soft
start function. This can be achieved by inserting a resistor
and a capacitor between pin I
(see Fig.10). An internal current source charges the
capacitor to V = I
approximately 0.5 V.
The start level and the time constant of the increasing
primary current level can be adjusted externally by
changing the values of R
The charging current I
pin I
pin I
start limiting the current I
current source is completely switched off.
2003 May 12
I
primary(max)
CC(start)
mains
=
GreenChip II SMPS control IC
sense
sense
R
SS
has been disconnected for a short period).
CC
and V
is below approximately 0.5 V. If the voltage on
exceeds 0.5 V, the soft start current source will
drops to UVLO, capacitor C
C
=
SS
CC
V
---------------------------------------------- -
CC(UVLO)
ocp
drops below 4.5 V (typical value). The
SS
start
–
R
R
SS
I
sense
level, however the IC will not start
SS
, but the IC will not start switching
SS
will flow as long as the voltage on
SS
SS
, with a maximum of
. At the V
R
and C
SS
sense
CC
CC
SS
V
and the sense resistor
CC(5V)
pin will cycle between
.
will drop again to the
CC(start)
VCC
CC
will be
voltage drops
level, the I
4%.
CC(5V)
pin
SS
10
Since the soft start current I
charging current, the R
current level by a maximum of 60 A (typical value).
5 V output
Pin V
The maximum output current must be limited to 1 mA.
If higher peak currents are required, an external RC
combination should limit the current drawn from this pin to
1 mA maximum.
The 5 V output voltage will be available as soon as the
start-up voltage is reached. As the high voltage supply can
not supply the 5 V pin during start-up and/or shutdown,
during latched shutdown (via pin LOCK or other latched
protection such as OVP or OTP), the voltage is switched
to zero.
Driver
The driver circuit to the gate of the power MOSFET has a
current sourcing capability of typically 170 mA and a
current sink capability of typically 700 mA. This permits
fast turn-on and turn-off of the power MOSFET for efficient
operation. A low driver source current has been chosen to
limit the V/ t at switch-on. This reduces Electro Magnetic
Interference (EMI) and also limits the current spikes
across R
handbook, halfpage
CC(5V)
0.5 V
sense
can be used for supplying external circuitry.
.
Fig.10 Soft start-up.
start-up
V ocp
I SS
SS
value will affect the V
2
SS
I sense
is subtracted from pin V
R SS
C SS
Product specification
TEA1654
R sense
MCE405
CC
charging
CC