HC5549_14 Datasheet, PDF (5/13 Pages) Intersil Corporation – Low Power SLIC with Battery Switch

HC5549
Electrical Specifications
Unless Otherwise Specified, T_A = -40°C to 85°C, V_BL = -24V, V_BH = -48V, V_CC = +5V, AGND = BGND = 0V, loop
current limit = 25mA. All AC Parameters are specified at 600Ω 2-wire terminating impedance over the frequency
band of 300Hz to 3.4kHz. Protection resistors = 0Ω. (Continued)
PARAMETER
TEST CONDITIONS
MIN TYP MAX UNITS
ON HOOK POWER DISSIPATION
Forward or Reverse
BSEL = 0
-
44
60
mW
Forward or Reverse
BSEL = 1
-
90
150 mW
Low Power Standby
BSEL = 1
-
37
60
mW
OFF HOOK POWER DISSIPATION
Forward or Reverse
BSEL = 0
-
290 310 mW
POWER SUPPLY REJECTION RATIO
V_CC to 2-Wire
f = 300Hz
f = 1kHz
-
40
-
dB
-
35
-
dB
f = 3.4kHz
-
28
-
dB
V_CC to 4-Wire
f = 300Hz
f = 1kHz
-
45
-
dB
-
43
-
dB
f = 3.4kHz
-
33
-
dB
V_BL to 2-Wire
V_BL to 4-Wire
V_BH to 2-Wire
V_BH to 4-Wire
300Hz ≤ f ≤ 3.4kHz
300Hz ≤ f ≤ 3.4kHz
300Hz ≤ f ≤ 3.4kHz
300Hz ≤ f ≤ 1kHz
1kHz < f ≤ 3.4kHz
-
30
-
dB
-
35
-
dB
-
33
-
dB
-
40
-
dB
-
45
-
dB
Design Equations
Loop Supervision Thresholds
SWITCH HOOK DETECT
The switch hook detect threshold is set by a single external
resistor, R_SH. Equation 1 is used to calculate the value of R_SH.
R_SH = 600 ⁄ I_SH
(EQ. 1)
The term I_SH is the desired DC loop current threshold. The
loop current threshold programming range is from 5mA to
15mA.
GROUND KEY DETECT
The ground key detector senses a DC current imbalance
between the Tip and Ring terminals when the ring terminal is
connected to ground. The ground key detect threshold is not
externally programmable and is internally fixed to 12mA
regardless of the switch hook threshold.
RING TRIP DETECT
The ring trip detect threshold is set by a single external
resistor, R_RT. I_RT should be set between the peak ringing
current and the peak off hook current while still ringing.
R_RT = 1800 ⁄ I_RT
(EQ. 2)
The capacitor C_RT, in parallel with R_RT, will set the ring trip
response time.
Loop Current Limit
The loop current limit of the device is programmed by the
external resistor R_IL. The value of R_IL can be calculated
using Equation 3.
R_IL
=
1_----7_---6_----0_-
I_LIM
(EQ. 3)
The term I_LIM is the desired loop current limit. The loop
current limit programming range is from 15mA to 45mA.
Impedance Matching
The impedance of the device is programmed with the
external component R_S. R_S is the gain setting resistor for
the feedback amplifier that provides impedance matching. If
complex impedance matching is required, then a complex
network can be substituted for R_S.
RESISTIVE IMPEDANCE SYNTHESIS
The source impedance of the device, Z_O , can be calculated
in Equation 4.
R_S = 400(Z_O)
(EQ. 4)
The required impedance is defined by the terminating
impedance and protection resistors as shown in Equation 5.
Z_O = Z_L – 2R_P
(EQ. 5)
5
FN4539.3