DatasheetQ Logo
Electronic component search and free download site.
Transistors,MosFET ,Diode,Integrated circuits

TEA1207T View Datasheet(PDF) - Philips Electronics

Part Name
Description
Manufacturer
TEA1207T
Philips
Philips Electronics Philips
TEA1207T Datasheet PDF : 20 Pages
1 2 3 4 5 6 7 8 9 10 Next Last
Philips Semiconductors
High efficiency DC/DC converter
Product specification
TEA1207T
Start-up
Start-up from low input voltage in boost mode is realized
by an independent start-up oscillator, which starts
switching the N-type power MOSFET as soon as the
voltage at pin UPOUT/DNIN is measured to be sufficiently
high. The switch actions of the start-up oscillator will
increase the output voltage. As soon as the output voltage
is high enough for normal regulation, the digital control
system takes over the control of the power MOSFETs.
Undervoltage lockout
As a result of too high load or disconnection of the input
power source, the output voltage can drop so low that
normal regulation cannot be guaranteed. In that case, the
device switches back to start-up mode. If the output
voltage drops down even further, switching is stopped
completely.
Shut-down
When the shut-down input is made HIGH, the converter
disables both power switches and the power consumption
is reduced to a few microamperes.
Power switches
The power switches in the IC are one N-type and one
P-type power MOSFET, having a typical drain-to-source
resistance of 0.20 and 0.22 respectively.
The maximum average current in the power switches is
0.60 A at Tamb = 80 °C.
Temperature protection
When the device operates in PWM mode, and the die
temperature gets too high (typically 175 °C), the converter
stops operating. It resumes operation when the die
temperature falls below 175 °C again. As a result,
low-frequent cycling between the on and off state will
occur. It should be noted that in the event of a device
temperature around the cut-off limit, the application differs
strongly from maximum specifications.
Current limiters
If the current in one of the power switches exceeds its limit
in the PWM mode, the current ramp is stopped
immediately, and the next switching phase is entered.
Current limiting is required to enable optimal use of energy
in Li-ion batteries, and to keep power conversion efficient
during temporary high loads. Furthermore, current limiting
protects the IC against overload conditions, inductor
saturation, etc. The current limiting level is set by an
external resistor.
External synchronization
If an external high-frequency clock is applied to the
synchronization clock input, the switching frequency in
PWM mode will be exactly that frequency divided by 22.
In the PFM mode, the switching frequency is always lower.
The quiescent current of the device increases when
external clock pulses are applied. In case no external
synchronization is necessary, the synchronization clock
input must be connected to ground level.
Behaviour at input voltage exceeding the specified
range
In general, an input voltage exceeding the specified range
is not recommended since instability may occur. There are
two exceptions:
Upconversion: at an input voltage higher than the target
output voltage, but up to 6 V, the converter will stop
switching and the internal P-type power MOSFET will be
conducting. The output voltage will equal the input
voltage minus some resistive voltage drop. The current
limiting function is not active.
Downconversion: when the input voltage is lower than
the target output voltage, but higher than 2.8 V, the
P-type power MOSFET will stay conducting resulting in
an output voltage being equal to the input voltage minus
some resistive voltage drop. The current limiting
function remains active.
2000 Nov 27
6
 

Share Link: 

datasheetq.com  [ Privacy Policy ]Request Datasheet ] [ Contact Us ]