Datasheet

Analog Integrated Circuit Device Data
Freescale Semiconductor 54
MC34708
Functional Block Description
Table 42. SW3 Electrical Specification
Characteristics noted under conditions BP = 3.6 V, V
BUS
= 5.0 V, - 40 C  T
A
 85 C, unless otherwise noted. Typical values
at BP = 3.6
V and T
A
= 25 °C under nominal conditions, unless otherwise noted.
Symbol Characteristic Min Typ Max Unit Notes
SW3 BUCK REGULATOR
V
SW3IN
Operating Input Voltage
• PWM operation, 0 < IL < I
MAX
• PFM operation, 0 < IL < IL
MAX
3.0
2.8
-
-
4.5
4.5
V
V
SW3ACC
Output Voltage Accuracy
• PWM mode including ripple, load regulation, and transients
• PFM Mode, including ripple, load regulation, and transients
Nom-3%
Nom-3%
Nom
Nom
Nom+3%
Nom+3%
mV
(50)
I
SW3
Continuous Output Load Current, V
INMIN
< BP < 4.65 V
• PWM mode
• PFM mode
-
-
-
50
500
-
mA
I
SW3PEAK
Current Limiter Peak Current Detection
•V
IN
= 3.6 V Current through Inductor
- 1.0 -
A
I
SW3
TRANSIENT
Transient Load Change
• 100 mA/µs
- - 250 mA
V
SW3OS-
START
Start-up Overshoot, IL = 100 mA/µs
- - 25 mV
t
ON-SW3
Turn-on Time
• Enable to 90% of end value IL = 0
- - 500
µs
f
SW3
Switching Frequency
• PLLX = 0
• PLLX = 1
-
-
2.0
4.0
-
-
MHz
I
SW3Q
Quiescent Current Consumption
• APSMODE, IL = 0 mA; device not switching
• PFM MODE, IL = 0 mA; device not switching
-
-
160
15
-
-
µA

SW3
Efficiency,
•PFM, 1.2 V, 1.0 mA
•PWM, 1.2 V, 120 mA
•PWM, 1.2 V, 250 mA
• PWM, 1.2V, 500 mA
-
-
-
-
71
79
82
81
-
-
-
-
%
(51)
Notes:
50. Transient loading for load steps of ILMAX/2
51. Efficiency numbers at VIN = 3.6 V, Excludes the quiescent current,