ISL9104IRUNZ-T Intersil, ISL9104IRUNZ-T Datasheet - Page 9

• Manufacturer Part Number: ISL9104IRUNZ-T
• Description: IC CONV SYNC 4.3MHZ 500MA 6-TDFN
• Manufacturer: Intersil
• Type: Step-Down (Buck)r

Specifications of ISL9104IRUNZ-T

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 3.3V
• Current - Output: 500mA
• Frequency - Switching: 4.3MHz
• Voltage - Input: 2.7 ~ 6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 6-µTDFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -

Block Diagram
Theory of Operation
The ISL9104, ISL9104A is a step-down switching regulator
optimized for battery-powered handheld applications. The
regulator operates at typical 4.3MHz fixed switching
frequency under heavy load condition to allow small external
inductor and capacitors to be used for minimal printed-circuit
board (PCB) area. At light load, the regulator can
automatically enter the skip mode (PFM mode) to reduce the
switching frequency to minimize the switching loss and to
maximize the battery life. The quiescent current under skip
mode under no load and no switch condition is typically only
20µA. The supply current is typically only 0.05µA when the
regulator is disabled.
NOTE: For Adjustable output version, the internal feedback resistor divider is disabled and the FB pin is directly connected
to the error amplifier.
FB
EN
*NOTE: FOR FIXED OUTPUT OPTIONS ONLY
SHUTDOWN
*NOTE
BANDGAP
VREF3
START
9
SOFT-
STAR
SOF
VREF
SLOPE
T
COMP
T
+
+
EAMP
SCP
FIGURE 22. FUNCTIONAL BLOCK DIAGRAM
X
ISL9104, ISL9104A
+
COMP
OSCILLATOR
PWM Control Scheme
The ISL9104, ISL9104A uses the peak-current-mode
pulse-width modulation (PWM) control scheme for fast
transient response and pulse-by-pulse current limiting.
Figure 22 shows the circuit functional block diagram. The
current loop consists of the oscillator, the PWM comparator
COMP, current sensing circuit, and the slope compensation
for the current loop stability. The current sensing circuit
consists of the resistance of the P-Channel MOSFET when it
is turned on and the Current Sense Amplifier (CSA). The
control reference for the current loops comes from the Error
Amplifier (EAMP) of the voltage loop.
OCP
SKIP
+
+
BLEEDING
FET
CONTROLLER
VREF1
PROTECTION
SHUTDOWN
VREF2
PWM/PFM
DRIVER
LOGIC
ZERO-CROSS
SENSING
100Ω
CSA
+
November 24, 2009
VIN
SW
GND
FN6829.4