1/20April 2004
■ COMPLETE INTERFACE BETWEEN LNB
AND I
2
C
TM
BUS
■ BUILT-IN DC/DC CONTROLLER FOR
SINGLE 12V SUPPLY OPERATION AND
HIGH EFFICIENCY (Typ. 94% @ 750mA)
■ TWO SELECTABLE OUTPUT CURRENT
LIMIT (450mA / 750mA)
■ BOTH COMPLIANT WITH EUTELSAT AND
DIRECT OUTPUT VOLTAGE
SPECIFICATION
■ ACCURATE BUILT-IN 22KHz TONE
OSCILLATOR SUITS WIDELY ACCEPTED
STANDARDS
■ FAST OSCILLATOR START-UP FACILITATES
DiSEqC
TM
ENCODING
■ BUILT-IN 22KHz TONE DETECTOR
SUPPORTS BI-DIRECTIONAL DiSEqC
TM
2.0
■ SEMI-LOWDROP POST REGULATOR AND
HIGH EFFICIENCY STEP-UP PWM FOR
LOW POWER LOSS: Typ. 0.56W @ 125mA
■ TWO OUTPUT PINS SUITABLE TO BYPASS
THE OUTPUT R-L FILTER AND AVOID ANY
TONE DISTORSION (R-L FILTER AS PER
DiSEqC 2.0 SPECs, see application circuit on
pag. 5)
■ CABLE LENGTH DIGITAL COMPENSATION
■ OVERLOAD AND OVER-TEMPERATURE
INTERNAL PROTECTIONS
■ OVERLOADAND OVER-TEMPERATURE I
2
C
DIAGNOSTIC BITs
■ LNB SHORT CIRCUIT SOA PROTECTION
WITH I
2
C DIAGNOSTIC BIT
■ +/- 4KV ESD TOLERANT ON INPUT/
OUTPUT POWER PINS
DESCRIPTION
Intended for analog and digital satellite STB
receivers/SatTV, sets/PC cards, the LNBH21 is a
monolithic voltage regulator and interface IC,
assembled in POWER SO-20, specifically
designed to provide the 13/18V power supply and
the 22KHz tone signalling to the LNB
downconverter in the antenna or to the multiswitch
box. In this application field, it offers a complete
solution with extremely low component count, low
power dissipation together with simple design and
I
2
C
TM
standard interfacing.
LNBH21
LNB SUPPLY AND CONTROL IC WITH
STEP-UP CONVERTER AND I
2
C INTERFACE
DSQIN
Enable
Preregul.+
U.V.lockout
+P.ON res.
V Select
Linear Post-reg
+Modulator
+Protections
Vup
VoRX
SDA
SCL
Vcc
Diagnostics
I²C interf.
Tone
Detector
DSQOUT
VoTX
DETIN
LNBH21
Byp
Gate
Sense
EXTM
ADDR
22KHz
Oscill.
TEN
Vup-Feedback
Step-up PWM
Controller
ISEL
BLOCK DIAGRAM
PowerSO-20