Datasheet

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1 Introduction
1.1 Background
The TPS56921 dc/dc converter is designed to provide up to a 9-A output. The TPS56921 implements
split-input power rails with separate input voltage inputs for the power stage and control circuitry. The
power stage input (PVIN) is rated for 1.6 V to 17 V whereas the control input (VIN) is rated for 4.5 V to 17
V. The TPS56921EVM-188 provides both inputs but is designed and tested using the PVIN connected to
VIN. Rated input voltage and output current range for the evaluation module are given in Table 1. This
evaluation module is designed to demonstrate the small printed-circuit-board areas that may be achieved
when designing with the TPS56921 regulator. The switching frequency is externally set at a nominal
500 kHz. The high-side and low-side MOSFETs are incorporated inside the TPS56921 package along with
the gate drive circuitry. The low drain-to-source on-resistance of the MOSFET allows the TPS56921 to
achieve high efficiencies and helps keep the junction temperature low at high output currents. The
compensation components are external to the integrated circuit (IC), and an external divider allows for an
adjustable output voltage. Additionally, the TPS56921 provides adjustable slow start, tracking, and
undervoltage lockout inputs. The absolute maximum input voltage is 20 V for the TPS56921EVM-188.
Table 1. Input Voltage and Output Current Summary
OUTPUT CURRENT
EVM INPUT VOLTAGE RANGE
RANGE
TPS56921EVM-188 VIN = 4.5 V to 17 V 0 A to 9 A
1.2 Performance Specification Summary
A summary of the TPS56921EVM-188 performance specifications is provided in Table 2. Specifications
are given for an input voltage of V
IN
= 12 V and an output voltage of 1.1 V, unless otherwise specified. The
TPS56921EVM-188 is designed and tested for V
IN
= 4.5 V to 17 V with the VIN and PVIN pins connect
together with the JP1 jumper. The ambient temperature is 25°C for all measurements, unless otherwise
noted.
Table 2. TPS56921EVM-188 Performance Specification Summary
SPECIFICATION TEST CONDITIONS MIN TYP MAX UNIT
V
IN
voltage range (PVIN = VIN) 4.5 12 17 V
V
IN
start voltage (internal UVLO) 4.0 V
V
IN
stop voltage (internal UVLO) 3.85 V
Output voltage setpoint 1.1 V
Output current range V
IN
= 8 V to 17 V 0 9 A
Line regulation I
O
= 4.5 A, V
IN
= 4.5 V to 17 V ±0.01 %
Load regulation V
IN
= 12 V, I
O
= 0 A to 9 A ±0.18 %
Voltage change –90 mV
I
O
= 2.25 A to 6.75 A
Recovery time 100 µs
Load transient response
Voltage change 90 mV
I
O
= 6.75 A to 2.25 A
Recovery time 100 µs
Loop bandwidth V
IN
= 12 V, I
O
= 4 A 50.1 kHz
Phase margin V
IN
= 12 V , I
O
= 4 A 63 °
I
O
= 9 A, measured with 330 µF added
Input ripple voltage 300 mVPP
capacitance at J2
Output ripple voltage I
O
= 8 A 10 mVPP
Output rise time 4 ms
Operating frequency 500 kHz
Maximum efficiency TPS56921EVM-188, V
IN
= 5 V, I
O
= 1.6 A 88.1 %
2
TPS56921EVM-188, 9-A, SWIFT™ Regulator Evaluation Module SLVU793–October 2012
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