ISL6421A Datasheet, PDF (5/12 Pages) Intersil Corporation – Single Output LNB Supply and Control Voltage Regulator with I2C Interface for Advanced Satellite Set-top Box Designs

ISL6421A
Electrical Specifications
Vcc = 12V, T_A
ENT = L, DCL
=
=
-20°C to +85°C, unless otherwise noted. Typical values are at T_A = 25°C. EN = H, LLC =
L, DSQIN = L, Iout = 12mA, unless otherwise noted. See software description section for
L,
I²C
access to the system. (Continued)
PARAMETER
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNITS
LINEAR REGULATOR
Drop-out Voltage
Iout = 450mA (Note 4)
-
1.2
-
V
DSQIN PIN
DSQIN pin logic Low
-
-
1.5V
V
DSQIN pin Logic HIGH
3.5
-
-
V
DSQIN pin Input Current
-
1
-
µA
CURRENT SENSE
Input Bias Current
Overcurrent Threshold
I_BIAS
Static current mode, DCL = H
-
700
-
nA
325
400
500
mV
ERROR AMPLIFIER
Open Loop Voltage Gain
Gain Bandwidth Product
PWM
A_OL
(Note 4)
GBP
(Note 4)
70
88
-
dB
10
-
-
MHz
Maximum Duty Cycle
90
93
-
%
Minimum Pulse Width
(Note 4)
-
20
-
ns
OSCILLATOR
Oscillator Frequency
THERMAL PROTECTION
f_o
Fixed at (10)(f_tone)
200
220
240
kHz
Thermal Shutdown
Temperature Shutdown Threshold
(Note 4)
-
150
-
Temperature Shutdown Hysteresis
(Note 4)
-
20
-
NOTES:
3. Internal digital soft-start
4. Voltage programming signals VSEL and LLC are implemented via the I²C bus.
IO1 = IO2 = 500mA.
5. Guaranteed by design.
Functional Pin Description
SYMBOL
SDA
SCL
Bidirectional data from/to I²C bus.
Clock from I²C bus.
FUNCTION
VSW
Input of the linear post-regulator.
PGND
Dedicated ground for the output gate driver of the PWM.
CS
Current sense input; connect Rsc at this pin for desired overcurrent value for the PWM.
SGND
Small signal ground for the IC.
AGND
Analog ground for the IC.
TCAP
Capacitor for setting rise and fall time of the output of the LNB. Use a capacitor value of 1µF or higher.
BYPASS
Bypass capacitor for internal 5V.
DSQIN
When HIGH this pin enables the internal 22kHz modulation for the LNB, Use this pin for tone enable function for the
LNB.
5
FN9167.2
February 11, 2005