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PDF ISL9104A Data sheet ( Hoja de datos )
| Número de pieza | ISL9104A | |
| Descripción | 500mA 4.3MHz Low IQ High Efficiency Synchronous Buck Converter | |
| Fabricantes | Intersil Corporation | |
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500mA 4.3MHz Low IQ High Efficiency Synchronous
Buck Converter
ISL9104, ISL9104A
The ISL9104, ISL9104A is a 500mA, 4.3MHz step-down
regulator, which is ideal for powering low-voltage
microprocessors in compact devices such as PDAs and cellular
phones. It is optimized for generating low output voltages
down to 0.8V. The supply voltage range is from 2.7V to 6V
allowing the use of a single Li+ cell, three NiMH cells or a
regulated 5V input. It has guaranteed minimum output current
of 500mA. A high switching frequency of 4.3MHz pulse-width
modulation (PWM) allows using small external components.
Under light load condition, the device operates at low IQ skip
mode with typical 20µA quiescent current for highest light
load efficiency to maximize battery life, and it automatically
switches to fixed frequency PWM mode under heavy load
condition.
The ISL9104, ISL9104A includes a pair of low ON-resistance
P-Channel and N-Channel internal MOSFETs to maximize
system efficiency and minimize the external component count.
100% duty-cycle operation allows less than 300mV dropout
voltage at 500mA.
The ISL9104, ISL9104A offers internal digital soft-start,
enable for power sequence, overcurrent protection and
thermal shutdown functions. In addition, the ISL9104,
ISL9104A offers a quick bleeding function that discharges the
output capacitor when the IC is disabled.
The ISL9104, ISL9104A is offered in a 1.6x1.6mm µTDFN
package. The complete converter occupies less than 0.5CM2.
Applications
• Single Li-ion Battery-Powered Equipment
• Mobile Phones and MP3 Players
• PDAs and Palmtops
• WCDMA Handsets
• Portable Instruments
Features
• High Efficiency Integrated Synchronous Buck Regulator with
up to 93% Efficiency
• 2.7V to 6.0V Supply Voltage
• 4.3MHz PWM Switching Frequency
• 500mA Guaranteed Output Current
• 3% Output Accuracy Over-Temperature and Line for Fixed
Output Options
• 20µA Quiescent Supply Current in Skip Mode
• Less than 1µA Logic Controlled Shutdown Current
• 100% Maximum Duty Cycle for Lowest Dropout
• Ultrasonic Switching Frequency at Skip Mode to Prevent
Audible Frequency Noise (For ISL9104A Only)
• Discharge Output Capacitor when Disabled
• Internal Digital Soft-Start
• Peak Current Limiting, Short Circuit Protection
• Over-Temperature Protection
• Chip Enable
• Small 6 Pin 1.6mmx1.6mm µTDFN Package
• Pb-Free (RoHS Compliant)
Related Literature
• See AN1522, “ISL9104xxxxEVAL1Z, ISL9104AxxxxEVAL1Z
Evaluation Board Application Manual”
Pin Configuration
ISL9104, ISL9104A
(6 LD 1.6x1.6 µTDFN)
TOP VIEW
VIN 1
EN 2
NC 3
6 SW
5 GND
4 FB
September 21, 2011
FN6829.5
1
100
95
90
85
80
75
70
65
60 VIN = 2.7V
55
VOUT = 1.8V
L = 1µH
50
1
10 100 1000
IOUT (mA)
FIGURE 1. EFFICIENCY vs OUTPUT CURRENT
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 |Copyright Intersil Americas Inc. 2008, 2009, 2011. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
1 page  
ISL9104, ISL9104A
Electrical Specifications Unless otherwise noted, all parameter limits are guaranteed over the recommended operating
conditions and the typical specifications are measured at the following conditions: TA = +25°C, VIN = VEN = 3.6V, L = 1.0µH, C1 = 4.7µF,
C2 = 4.7µF, IOUT = 0A (see “Typical Applications” on page 2). Boldface limits apply over the operating temperature range,
-40°C to +85°C. (Continued)
PARAMETER
SYMBOL
TEST CONDITIONS
MIN MAX
(Note 6) TYP (Note 6) UNITS
SW Leakage Current
SW at Hi-Z state
- 0.01 2
µA
PWM Switching Frequency
SW Minimum On-Time
fS VIN = 3.6V, TA = -20°C to +85°C
3.6 4.3 4.9 MHz
- 65 -
ns
Soft-Start-Up Time
- 1.0 - ms
EN
Logic Input Low
- - 0.4 V
Logic Input High
1.4 - - V
Logic Input Leakage Current
- 0.1 1 µA
Thermal Shutdown
- 130 -
°C
Thermal Shutdown Hysteresis
- 30 - °C
NOTE:
6. Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by characterization
and are not production tested.
Typical Operating Performance
100
90 VIN = 2.7V
80
70
60 VIN = 3.8V
VIN = 4.9V
50
40
30
20
10
0
0 0.1 0.2 0.3 0.4 0.5
LOAD CURRENT (A)
FIGURE 3. EFFICIENCY vs LOAD CURRENT (VOUT = 1.5V)
100
90
80
70 VIN = 3.5V
60
VIN = 4.5V
VIN = 5.5V
50
40
30
20
10
0
0 0.1 0.2 0.3 0.4 0.5
LOAD CURRENT (A)
FIGURE 4. EFFICIENCY vs LOAD CURRENT (VOUT = 2.5V)
30
25 T = +85°C
T = +25°C
20
15
T = -45°C
10
2.70 3.25 3.80 4.35 4.90 5.45
INPUT VOLTAGE (V)
6.00
FIGURE 5. INPUT QUIESCENT CURRENT vs VIN (VOUT = 2.5V)
5
1.630
1.625
1.620
LOAD CURRENT RISING
1.615
1.610
1.605
LOAD CURRENT FALLING
1.600
0
100 200 300 400 500
IOUT (mA)
FIGURE 6. OUTPUT VOLTAGE vs LOAD CURRENT (VIN = 3.6V,
VOUT = 1.6V)
FN6829.5
September 21, 2011
5 Page 
ISL9104, ISL9104A
Overcurrent Protection
The overcurrent protection is provided on ISL9104, ISL9104A when
overload condition happens. It is realized by monitoring the CSA
output with the OCP comparator, as shown in Figure 23 on page 9.
When the current at P-Channel MOSFET is sensed to reach the
current limit, the OCP comparator is trigged to turn off the
P-Channel MOSFET immediately.
Short-Circuit Protection
ISL9104, ISL9104A has a Short-Circuit Protection (SCP)
comparator, which monitors the FB pin voltage for output short-
circuit protection. When the output voltage is sensed to be lower
than a certain threshold, the SCP comparator reduces the PWM
oscillator frequency to a much lower frequency to protect the IC
from being damaged.
Undervoltage Lockout (UVLO)
When the input voltage is below the Undervoltage Lock Out
(UVLO) threshold, ISL9104, ISL9104A is disabled.
Soft-Start
The soft-start feature eliminates the in-rush current during the circuit
start-up. The soft-start block outputs a ramp reference to both the
voltage loop and the current loop. The two ramps limit the inductor
current rising speed as well as the output voltage speed so that the
output voltage rises in a controlled fashion.
Low Dropout Operation
The ISL9104, ISL9104A features low dropout operation to maximize
the battery life. When the input voltage drops to a level that
ISL9104, ISL9104A can no longer operate under switching
regulation to maintain the output voltage, the P-Channel MOSFET is
completely turned on (100% duty cycle). The dropout voltage under
such condition is the product of the load current and the
ON-resistance of the P-Channel MOSFET. Minimum required input
voltage VIN under this condition is the sum of output voltage plus the
voltage drop cross the inductor and the P-Channel MOSFET switch.
Thermal Shut Down
The ISL9104, ISL9104A provides built-in thermal protection
function. The thermal shutdown threshold temperature is
+130°C (typ) with a 30°C (typ) hysteresis. When the internal
temperature is sensed to reach +130°C, the regulator is
completely shut down and as the temperature drops to +100°C
(typ), the ISL9104, ISL9104A resumes operation starting from
the soft-start.
Applications Information
Inductor and Output Capacitor Selection
To achieve better steady state and transient response, ISL9104,
ISL9104A typically uses a 1.0µH inductor. The peak-to-peak
inductor current ripple can be expressed in Equation 1:
ΔI
=
VO
•
⎜⎛1
⎝
–
V-V---I-O-N--⎠⎟⎞
------------L----•-----f--S------------
(EQ. 1)
In Equation 1, usually the typical values can be used but to have
a more conservative estimation, the inductance should consider
the value with worst case tolerance; and for switching frequency
fS, the minimum fS from the “Electrical Specifications” table on
page 4 can be used.
To select the inductor, its saturation current rating should be at
least higher than the sum of the maximum output current and
half of the delta calculated from Equation 1. Another more
conservative approach is to select the inductor with the current
rating higher than the P-Channel MOSFET peak current limit.
Another consideration is the inductor DC resistance since it
directly affects the efficiency of the converter. Ideally, the
inductor with the lower DC resistance should be considered to
achieve higher efficiency.
Inductor specifications could be different from different
manufacturers so please check with each manufacturer if
additional information is needed.
For the output capacitor, a ceramic capacitor can be used
because of the low ESR values, which helps to minimize the
output voltage ripple. A typical value of 4.7µF/6.3V ceramic
capacitor should be enough for most of the applications and the
capacitor should be X5R or X7R.
Input Capacitor Selection
The main function for the input capacitor is to provide decoupling
of the parasitic inductance and to provide filtering function to
prevent the switching current from flowing back to the battery rail.
A 4.7µF/6.3V ceramic capacitor (X5R or X7R) is a good starting
point for the input capacitor selection.
Output Voltage Setting Resistor Selection
For ISL9104, ISL9104A adjustable output option, the voltage
resistors, R1 and R2, as shown in Figure 2, set the desired output
voltage values. The output voltage can be calculated using
Equation 2:
VO
=
VF
B
•
⎛
⎜
1
⎝
+
R-R----12-⎠⎟⎞
(EQ. 2)
where VFB is the feedback voltage (typically it is 0.8V). The
current flowing through the voltage divider resistors can be
calculated as VO/(R1 + R2), so larger resistance is desirable to
minimize this current. On the other hand, the FB pin has leakage
current that will cause error in the output voltage setting. The
leakage current has a typical value of 0.1µA. To minimize the
accuracy impact on the output voltage, select the R2 no larger
than 200kΩ.
For adjustable output versions, C3 (shown in Figure 2 on page 2)
is highly recommended for improving stability and achieving
better transient response.
Table 1 provides the recommended component values for some
output voltage options.
11 FN6829.5
September 21, 2011
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet ISL9104A.PDF ] | |
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