TLF51801ELV Datasheet, PDF (8/29 Pages) Infineon Technologies AG – 10 A synchronous DC/DC Step-Down Controller

TLF51801ELV
Regulator
5
Regulator
5.1
Description
The TLF51801ELV is a synchronous step down controller for output currents up to 10 Amps. The power stage
consists of two external MOSFETs with logic level gate signal. The switching frequency can be adjusted between
100 and 700 kHz by connecting an external resistor between pin SYNC/FREQ and GND (FREQ-mode). By
connecting this pin to a frequency source the TLF51801ELV might be synchronized to a frequency between 350
and 700 kHz (SYNC-mode).
A valid high signal at pin EN will start the regulator. Then it will ramp up with a soft start ramp, which is derived
from the switching frequency (i.e.: the soft start ramp will last around 1 msec at a switching frequency of 500 kHz).
The regulator is working in voltage mode, there is no feedforward function included and it operates in continuous
conduction mode only.
An external compensation network connected to pin COMP is necessary to compensate the switching ripple on
the feedback line. The compensation network must be adapted to the application.
The regulator can withstand a short circuit at the output. The current limitation can be implemented measuring the
drop across the Rdson of the external high-side MOSFET (Rdson-configuration), or by shunt resistor located in
series with the drain of high-side MOSFET (Shunt-configuration).
The output voltage is monitored using pin FB. If the output voltage exceeds the overvoltage threshold (10% higher
than the regulated output voltage), the low-side external MOSFET is turned on in order to discharge the output
capacitor and lower the output voltage to the nominal value.
SENSELOW
SENSEHIGH
BLANK _OC
UV
COMP
FB
-
EA
+
+ VREF
- _1.2V
COMP
UV
BG
SOFTSTART LOGIC
SAWTOOTH GEN
OV
BG
OVERVOLTAGESHUTDOWN
CLOCK
Force
Min Duty
L
Skipping
Mode
O
G
IC
CROSS CONDUCTION
PWM SAFETY LOGIC
LS
UG
DRIVER
PHS
DETECT
V_LS
POR
IVCC
LG
DRIVER
TSD
THERMALSHUTDOWN
Figure 3 Block Diagram Buck Regulator
BTS
UG
BUO
LG
PGND
Data sheet
8
Rev. 1.0.1, 2013-04-15