L6740L STMicroelectronics, L6740L Datasheet - Page 24

• Manufacturer Part Number: L6740L
• Description: IC HYBRID CONTROLLERS 48TQFP
• Manufacturer: STMicroelectronics

Specifications of L6740L

• Applications: Hybrid Controllers
• Voltage - Supply: 9 V ~ 15 V
• Current - Supply: 20mA
• Operating Temperature: 0°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 48-TQFP Exposed Pad, 48-eTQFP, 48-HTQFP, 48-VQFP
• Number Of Outputs: 2
• Output Current: 170 A
• Input Voltage: 13.2 V
• Mounting Style: SMD/SMT
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: 0 C
• Hybrid Controller: compatible with PVI and SVI CPUs
• Dual Controller: 2 to 4 scalable phases for CPU CORE, 1 phase for NB
• Dual Over-current Protection: Average and per-phase
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Input: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Output voltage positioning
6.1
Caution:
6.2
24/44
CORE section - phase # programming
CORE section implements a flexible 2 to 4 interleaved-phase converter. To program the
desired number of phase, simply short to SGND the PWMx signal that is not required to be
used according to
phase operation, short PWM3 and PWM4 to SGND.
For the disabled phase(s), the current reading pins need to be properly connected to avoid
errors in current-sharing and voltage-positioning: CSx+ needs to be connected to the
regulated output voltage while CSx- needs to be connected to CSx+ through the same Rg
resistor used for the active phases.
Table 11.
CORE section - current reading and current sharing loop
L6740L embeds a flexible, fully-differential current sense circuitry for the CORE section that
is able to read across inductor parasitic resistance or across a sense resistor placed in
series to the inductor element. The fully-differential current reading rejects noise and allows
placing sensing element in different locations without affecting the measurement's accuracy.
The trans-conductance ratio is issued by the external resistor Rg placed outside the chip
between CSx- pin toward the reading points. The current sense circuit always tracks the cur-
rent information, the pin CSx+ is used as a reference keeping the CSx- pin to this voltage. To
correctly reproduce the inductor current an R-C filtering network must be introduced in par-
allel to the sensing element. The current that flows from the CSx- pin is then given by the fol-
lowing equation (See
Considering now to match the time constant between the inductor and the R-C filter applied
(Time constant mismatches cause the introduction of poles into the current reading network
causing instability. In addition, it is also important for the load transient response and to let
the system show resistive equivalent output impedance) it results:
R
about 35 μA (I
I
------ -
R
CSx-
L
G
L
Phase number
resistor is typically designed in order to have an information current I
=
=
R C
DCR
------------ -
⋅
1
2
3
4
R
G
CORE section - phase number programming
⋅
⇒
1
------------------------------------- - I ⋅
OCTH
1
+
+
s L DCR
Table
s R C
I
⋅
CSx-
) at the OC threshold.
⋅
⁄
Figure
⋅
=
PWM1
11. For three phase operation, short PWM4 to SGND while for two
------- - I
R
R
G
L
⋅
10):
PHASEx
PHASEx
to Driver
=
I
INFOx
to Driver
PWM2
to Driver
n/a
PWM3
SGND
INFOx
in the range of
PWM4
SGND
SGND
L6740L