TPS51640A, TPS59640, TPS59641
SLUSAQ2 –JANUARY 2012
www.ti.com
Table 1. Key External Component Recommendations
FUNCTION
High-side MOSFET
Low-side MOSFET
Powerblock MOSFET
MANUFACTURER
Texas Instruments
COMPONENT NUMBER
CSD17302Q5A
Texas Instruments
Texas Instruments
Panasonic
CSD17303Q5
CSD87350Q5D
ETQP4LR36AFC
MPCH1040LR36,
MPCG1040LR36
NEC-Tokin
TOKO
Inductors
FDUE1040J-H-R36,
FCUL1040xxR36
ALPS
GLMDR3601A
Panasonic
Sanyo
EEFLXOD471R4
2TPLF470M4E
Bulk Output Capacitors
KEMET
Murata
T528Z477M2R5AT
GRM21BR60J106KE19L
GRM21BR60J226ME39L
ECJ2FB0J106K
Murata
Ceramic Output Capacitors
Panasonic
Panasonic
ECJ2FB0J226K
NCP15WF104F03RC,
NCP18WF104F03RC
Murata
NTC Thermistors
Sense Resistors
Panasonic
Vishay
ERTJ1VS104F, ERTJ0ES104F
WSK0612L7500FEA
Stackpole
CSSK0612FTL750
DETAILED DESCRIPTION
Functional Overview
The TPS51640A, TPS59640, and TPS59641 are a DCAP+™ mode adaptive on-time controllers.
The output voltage is set using a DAC that outputs a reference in accordance with the 8-bit VID code defined in
Intel IMVP-7 PWM Specification document. In adaptive on-time converters, the controller varies the on-time as a
function of input and output voltage to maintain a nearly constant frequency during steady-state conditions. In
conventional voltage-mode constant on-time converters, each cycle begins when the output voltage crosses to a
fixed reference level. However, in these devices, the cycle begins when the current feedback reaches an error
voltage level which corresponds to the amplified difference between the DAC voltage and the feedback output
voltage. In the case of two-phase or three-phase operation, the current feedback from all the phases is summed
up at the output of the internal current-sense amplifiers.
This approach has two advantages:
•
•
The amplifier DC gain sets an accurate linear load-line; this is required for CPU core applications.
The error voltage input to the PWM comparator is filtered to improve the noise performance.
In addition, the difference of the DAC-to-output voltage and the current feedback goes through an integrator to
give a more or less linear load-line even at light loads where the inductor current is in discontinuous conduction
mode (DCM).
In a steady-state condition, the phases of the TPS51640A, TPS59640, and TPS59641 switch 180°
phase-displacement for two-phase mode and 120° phase-displacement for three-phase mode. The phase
displacement is maintained both by the architecture (which does not allow both high-side gate drives to be on in
any condition except transients) and the current ripple (which forces the pulses to be spaced equally). The
controller forces current sharing adjusting the on-time of each phase. Current balancing requires no user
intervention, compensation, or extra components.
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