STLC3055
EXTERNAL COMPONENTS
(continued)
Name
CRD (6)
Q1
Function
High frequency noise filter
DC/DC converter switch P ch.
MOS transistor
RDS(ON)≤1.2Ω,VDS = -100V
Total gate charge=20nC max.
with VGS=4.5V and VDS=1V
ID>500mA
Vr > 100V, t
RR
≤
50ns
RSENSE = 100mV/I
PK
DC Resistance
≤
0.1
Ω
(9)
Formula
Typ. Value
100nF 10% 15VL
Possible choiches:
IRF9510 or IRF9520 or
IRF9120 or equivalent
SMBYW01-200
or equivalent
110mΩ
@I
PK
= 900mA
L=125
µ
H RFP1304PV
(Manuf.: All Inductive)
or SUMIDA CDRH125
or equivalent
220pF to 470pF (10)
250K
Ω
<RF1<300K
Ω
(7)
300kW 1%
@ V
BATR
= -70V
9.1kΩ 1%
D1
RSENSE
L (8)
DC/DC converter series diode
DC/DC converter peak current
limiting
DC/DC converter inductor
CF1
RF1
RF2
DC/DC converter feedback loop
stability
Negative battery programming
level
Negative battery programming
level
(1) In case Zs=Zl, ZA and ZB can be replaced by two resistors of same value: RA=RB=|Zs|.
(2) In this case CTTX is just operating as a DC decoupling capacitor (fp=100Hz).
(3) Defining ZTTX as the impedance of RTTX in series with CTTX, RTTX and CTTX can also be calculated from the following formula:
ZTTX=50*(Zlttx+2Rp+18
Ω
).
(4) CVpos should be defined depending on the power supply current capability and maximum allowable ripple.
(5) For low ripple application use 2x47
µ
F in parallel.
(6) Can be saved if proper PCB layout avoid noise coupling on RD pin (high impedance input).
(7) RF1 sets the self generated battery voltage in RING and ACTIVE(Il=0) mode as follows:
267k
Ω
V
BAT(ACTIVE)
V
BATR(RING)
-46V
-62V
280k
Ω
-48V
-65V
294kW
-49V
-68V
300k
Ω
-50V
-70V
VBATR should be defined considering the ring peak level required (Vringpeak=VBATR-6V typ.).
The above relation is valid provided that the Vpos power supply current capability and the RSENSE programming allow to source all the
current requested by the particular ringer load configuration.
(8) Core: MICROMETALS T50-26C IRON POWDER, AL-VALUE 61nH/N2
Current rating: 2A (50/60Hz)
Operating Temperature -25° to +60° Centigrades
Inductance: 14
µ
H +/-15% at 1KHz, 1mA
DC resistance of winding: MAX.100 mOhm
Code: RFY1303
Wire: UEW2, 0,60 mm
Turns: 50
Inductance (f=1KHz): >125
µ
H
(9) For high efficiency in HI-Z mode coil resistance @125kHz must be <3ohm
(10) Function of this capacitor is to introduce a zero at the resonance frequency for loop stability. In case some parasitic resistance are already
present in the loop (Coil, CVBAT, PCB layout), the presence of this capacitor can degrade the device noise performances; in this case CF1
should be removed being the loop stability already guaranteed by the parasitic resistance.
11/22
STMICROELECTRONICS [ STMICROELECTRONICS ]
