SI8250-IM Silicon Laboratories Inc, SI8250-IM Datasheet - Page 20

• Manufacturer Part Number: SI8250-IM
• Description: IC DIGITAL PWR CONTROLLER 32LQFP
• Manufacturer: Silicon Laboratories Inc
• Type: Power Supply Supervisoryr

Specifications of SI8250-IM

• Applications: Digital Power Controller
• Voltage - Supply: 2.25 V ~ 2.75 V
• Current - Supply: 26mA
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 28-QFN
• Product: MOSFET Gate Drivers
• Supply Voltage (min): 2.25 V
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• For Use With: 336-1323 - KIT REFERENCE DESIGN FOR SI825X
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Voltage - Input: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Si8250/1/2
5.2. Single-Phase Point of Load (POL)
A 65 W, 400 KHz Si8252 based single phase POL
converter block diagram is shown in Figure 8. DPWM
outputs PH1 and PH2 control the gates of the buck and
synchronous switching transistors. A lossless current
sensing method that relies on the resistor and
inductance of the inductor is used to measure the
current for overcurrent protection. The input voltage is
measured using the resistor divider network and analog
input port AIN0 of 12bit, 200 kHz ADC0.
20
VIN
CIN
Figure 8. Single-Phase POL Block Diagram
Converter
DRIVER
DRIVER
DIFFERENTIAL
AMPLIFIER
VIN
AIN0
PH1
PH2
Si8252
L
+2.5 V
VDD
GND
Vsense
C
Ipk
Ipk
Ipk
Vout
Rev. 1.0
When power is applied, the CPU executes an internal
reset followed by initialization of all parameters. The
Si8252 remains in a low-power state, monitoring
digitized V
this time, the controller is fully enabled and executes
soft-start by monitoring output voltage while sequentially
incrementing the loop voltage reference (REFDAC) until
the supply output voltage is within the specified range,
at which time steady-state operation begins. As in the
previous half-bridge example, transient response is
improved by adjusting loop gain at the onset of a
transient (i.e. nonlinear control). The efficiency of the
POL converter can be optimized over the complete load
range by dynamically adjusting the dead-times. Typical
efficiency simulation results for the POL are shown in
Figure 9. In this case, the single-phase POL operates at
a PWM frequency of 400 kHz with an output voltage of
3.3 V and an input voltage range of 10 to 15 V. The
curve shows the efficiency with an input voltage of
12.0 V.
Eff Io
( )
95
90
85
80
0
IN
data until V
Figure 9. POL Efficiency
5
10
IN
is within specified limits. At
Io
15
20
25