MICROCHIP MCP1603 Technical data

MCP1603
1
2
3
4
5
L
X
VFB/V
OUT
SHDN
GND
V
IN
5-Lead TSOT
MCP1603
1
2
34
5
L
X
VFB/V
OUT
SHDN
GND
V
IN
MCP1603L
1
2
3
4
8
7
6
5
L
X
VFB/V
OUT
SHDN
GND V
IN
NC
NC
NC
8-Lead 2x3 DFN
2.0 MHz, 500 mA Synchronous Buck Regulator
Features
• Over 90% Typical Efficiency
• Output Current Up To 500 mA
• Low Quiescent Current = 45 µA, typical
• Low Shutdown Current = 0.1 µA, typical
• Adjustable Output Voltage:
• Fixed Output Voltage:
- 1.2V, 1.5V, 1.8V, 2.5V, and 3.3V
• 2.0 MHz Fixed-Frequency PWM (Heavy Load)
• Automatic PWM to PFM Mode Transition
• 100% Duty Cycle Operation
• Internally Compensated
• Undervoltage Lockout (UVLO)
• Overtemperature Protection
• Space Saving Packages:
- 5-Lead TSOT
- 8-Lead 2X3 DFN
Applications
• Cellular Telephones
• Portable Computers
• Organizers / PDAs
• USB Powered Devices
• Digital Cameras
• Portable Equipment
• +5V or +3.3V Distributed Systems
General Description
The MCP1603 is a high efficient, fully integrated 500 mA synchronous buck regulator whose 2.7V to
5.5V input voltage range makes it ideally suited for applications powered from 1-cell Li-Ion or 2-cell/3-cell NiMH/NiCd batteries.
At heavy loads, the MCP1603 operates in the 2.0 MHz fixed frequency PWM mode which provides a low noise, low output ripple, small-size solution. When the load is reduced to light levels, the MCP1603 automatically changes operation to a PFM mode to minimize quiescent current draw from the battery. No intervention is necessary for a smooth transition from one mode to another. These two modes of operation allow the MCP1603 to achieve the highest efficiency over the entire operating current range.
The MCP1603 is available with either an adjustable or fixed output voltage. The available fixed output voltage options are 1.2V, 1.5V, 1.8V, 2.5V, and 3.3V. When a fixed option is used, only three additional small external components are needed to form a complete solution. Couple this with the low profile, small-foot print packages and the entire system solution is achieved with minimal size.
Additional protection features include: UVLO, overtemperature, and overcurrent protection.
Package Types
© 2007 Microchip Technology Inc. DS22042A-page 1
MCP1603
V
IN
SHDN
GND
V
FB
L
X
VIN
2.7V To 4.5V
V
OUT
1.8V @ 500 mA
C
OUT
4.7 µF
C
IN
4.7 µF
L
1
4.7 µH
50
55
60
65
70
75
80
85
90
95
100
0.1 1 10 100 1000 Output Current (mA)
Efficiency (%)
V
OUT
= 1.8V
VIN = 2.7V
VIN = 3.6V
VIN = 4.5V
Typical Application Circuit
DS22042A-page 2 © 2007 Microchip Technology Inc.
MCP1603
ILIM
PWM
ILIM
PFM
IPEAK
PWM
IPEAK
PFM
V
IN
SHDN
VFB/V
OUT
GND
L
X
Band
Gap
UVLO
Switch Drive
UVLO
V
REF
Logic and timing
S
RQ
Q
Soft Start
V
REF
PWM/PFM
Logic
V
REF
Slope Comp
OSC
-IPK Limit
UVLO
Thermal
Shutdown
TSD
EA
POFF NOFF
PWM/PFM
TSD
PFM Error Amp
PWM Error Amp
OV Threshold
UV Threshold
IPK Limit
-ILPK
IPEAK
PWM
IPEAK
PFM
Disable Switcher
-ILPK
Functional Block Diagram
© 2007 Microchip Technology Inc. DS22042A-page 3
MCP1603

1.0 ELECTRICAL CHARACTERISTICS

Absolute Maximum Ratings †
VIN - GND.......................................................................+6.0V
All Other I/O ...............................(GND - 0.3V) to (V
to GND .............................................. -0.3V to (VIN + 0.3V)
L
X
Output Short Circuit Current..................................Continuous
Power Dissipation (Note 5)..........................Internally Limited
Storage Temperature.....................................-65°C to +150°C
Ambient Temp. with Power Applied.................-40°C to +85°C
Operating Junction Temperature...................-40°C to +125°C
ESD Protection On All Pins:
HBM..............................................................................4 kV
MM...............................................................................300V
+ 0.3V)
IN
Notice: Stresses above those listed under "Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operational sections of this specification is not intended. Exposure to maximum rating conditions for extended periods may affect device reliability.
DC CHARACTERISTICS
Electrical Characteristics: Unless otherwise indicated, VIN = SHDN = 3.6V, C
I
= 100 mA, TA = +25°C. Boldface specifications apply over the TA range of -40°C to +85°C.
OUT
Parameters Sym Min Typ Max Units Conditions
Input Characteristics
Input Voltage V Maximum Output Current I Shutdown Current I
IN_SHDN
Quiescent Current I
IN
OUT
Q
2.7 5.5 V Note 1
500 ——mANote 1
0.1 1 µA SHDN = GND —4560 µA SHDN = VIN, I
Shutdown/UVLO/Thermal Shutdown Characteristics
SHDN
, Logic Input Voltage Low V
SHDN
, Logic Input Voltage High V
SHDN, Input Leakage Current I
IL
IH
L_SHDN
——15 %VINVIN = 2.7V to 5.5V
45 ——%VINVIN = 2.7V to 5.5V
-1.0 ±0.1 1.0 µA VIN = 2.7V to 5.5V
Undervoltage Lockout UVLO 2.12 2.28 2.43 VV Undervoltage Lockout Hysteresis UVLO Thermal Shutdown T Thermal Shutdown Hysteresis T Note 1: The minimum V
has to meet two conditions: VIN 2.7V and VIN V
IN
SHD
SHD-HYS
HYS
140 mV — 150 °C Note 4, Note 5 —10—°CNote 4, Note 5
2: Reference Feedback Voltage Tolerance applies to adjustable output voltage setting.
is the output voltage setting.
3: V
R
4: The maximum allowable power dissipation is a function of ambient temperature, the maximum allowable
temperature and the thermal resistance from junction to air (i.e. T allowable power dissipation causes the device to initiate thermal shutdown.
5: The internal MOSFET switches have an integral diode from the L
to the GND pin. In cases where these diodes are forward-biased, the package power dissipation limits must be adhered to. Thermal protection is not able to limit the junction temperature for these cases.
6: The current limit threshold is a cycle-by-cycle peak current limit.
= CIN = 4.7 µF, L = 4.7 µH, V
OUT
Falling
IN
+ 0.5V.
OUT
, TJ, θJA). Exceeding the maximum
A
pin to the VIN pin, and from the LX pin
X
(ADJ) = 1.8V,
OUT
= 0 mA
OUT
DS22042A-page 4 © 2007 Microchip Technology Inc.
MCP1603
DC CHARACTERISTICS (CONTINUED)
Electrical Characteristics: Unless otherwise indicated, VIN = SHDN = 3.6V, C
I
= 100 mA, TA = +25°C. Boldface specifications apply over the TA range of -40°C to +85°C.
OUT
Parameters Sym Min Typ Max Units Conditions
Output Characteristics
Adjustable Output Voltage Range V Reference Feedback Voltage V
Reference Feedback Voltage To le r an c e
Feedback Input Bias Current I Output Voltage Tolerance Fixed V
V
Line Regulation V
Load Regulation V
Internal Oscillator Frequency F Start Up Time T R
P-Channel R
DSon
R
N-Channel R
DSon
L
Pin Leakage Current I
X
Positive Current Limit Threshold +I Note 1: The minimum V
has to meet two conditions: VIN 2.7V and VIN V
IN
LX(MAX)
OUT
FB
VFB
OUT
OUT
LINE-
REG
LOAD­REG
OSC
SS
DSon-P
DSon-N
LX
0.8 4.5 V Note 2
—0.8—V
-3.0 +3.0 % TA = -40°C to +25°C
-2.5 +2.5 % T —0.1—nA
-3.0% V
-2.5 V
R
R
—0.3—%/VV
—0.35—%VIN=VR+1.5V,
1.5 2.0 2.8 MHz
—0.6—msT — 500 mΩ IP=100mA — 500 mΩ IN= 100 mA
-1.0 ±0.1 1.0 µA SHDN =0V, VIN=5.5V,
860 mA Note 6
2: Reference Feedback Voltage Tolerance applies to adjustable output voltage setting. 3: V
is the output voltage setting.
R
4: The maximum allowable power dissipation is a function of ambient temperature, the maximum allowable
temperature and the thermal resistance from junction to air (i.e. T allowable power dissipation causes the device to initiate thermal shutdown.
5: The internal MOSFET switches have an integral diode from the L
to the GND pin. In cases where these diodes are forward-biased, the package power dissipation limits must be adhered to. Thermal protection is not able to limit the junction temperature for these cases.
6: The current limit threshold is a cycle-by-cycle peak current limit.
= CIN = 4.7 µF, L = 4.7 µH, V
OUT
= +25°C to +85°C
A
+3.0% % TA = -40°C to +25°C, Note 3
+2.5 % TA = +25°C to +85°C, Note 3
= VR + 1V to 5.5V,
IN
=100mA
I
OUT
I
= 100 mA to 500 mA
LOAD
= 10% to 90%
R
LX=0V, LX=5.5V
+ 0.5V.
OUT
, TJ, θJA). Exceeding the maximum
A
pin to the VIN pin, and from the LX pin
X
(ADJ) = 1.8V,
OUT
© 2007 Microchip Technology Inc. DS22042A-page 5
MCP1603
TEMPERATURE SPECIFICATIONS
Electrical Specifications: Unless otherwise indicated, all limits are specified for: VIN+2.7Vto5.5V
Parameters Sym Min Typ Max Units Conditions
Temperature Ranges
Operating Junction Temperature Range
Storage Temperature Range T Maximum Junction Temperature T
Package Thermal Resistances
Thermal Resistance, 5L-TSOT θ
Thermal Resistance, 8L-2x3 DFN θ
T
J
A
J
JA
JA
-40 +125 °C Steady State
-65 +150 °C — +150 °C Transient
256 °C/W Typical 4-layer Board with
Internal Ground Plane
84.5 °C/W Typical 4-layer Board with
Internal Ground Plane and 2-Vias in Thermal Pad
DS22042A-page 6 © 2007 Microchip Technology Inc.
MCP1603
40
41
42
43
44
45
46
47
48
49
50
-40 -25 -10 5 20 35 50 65 80 95 110 125
Ambient Temperature (
o
C)
Quiescent Current (µA)
V
OUT
= 1.8V
VIN = 4.2V
VIN = 3.0V
VIN = 3.6V
60
65
70
75
80
85
90
95
100
2.7 3.05 3.4 3.75 4.1 4.45 4.8 5.15 5.5
Input Voltage (V)
Efficiency (%)
V
OUT
= 1.2V
I
OUT
= 100 mA
I
OUT
= 500 mA
I
OUT
= 300 mA
70
75
80
85
90
95
100
2.7 3.05 3.4 3.75 4.1 4.45 4.8 5.15 5.5
Input Voltage (V)
Efficiency (%)
V
OUT
= 1.8V
I
OUT
= 100 mA
I
OUT
= 500 mA
I
OUT
= 300 mA
40
42
44
46
48
50
52
2.7 3.05 3.4 3.75 4.1 4.45 4.8 5.15 5.5
Input Voltage (V)
Quiescent Current (µA)
TA = - 40oC
TA = +25oC
TA = +90oC
20
30
40
50
60
70
80
90
100
0.1 1 10 100 1000
Output Current (mA)
Efficiency (%)
V
OUT
= 1.2V
VIN = 4.2V
VIN = 2.7V
VIN = 3.6V
20
30
40
50
60
70
80
90
100
0.1 1 10 100 1000
Output Current (mA)
Efficiency (%)
V
OUT
= 1.8V
VIN = 4.2V
VIN = 2.7V
VIN = 3.6V
2.0 TYPICAL PERFORMANCE CURVES
Note: The graphs and tables provided following this note are a statistical summary based on a limited number of
samples and are provided for informational purposes only. The performance characteristics listed herein are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified operating range (e.g., outside specified power supply range) and therefore outside the warranted range.
Note: Unless otherwise indicated, VIN= SHDN =3.6V, C T
= +25°C. Adjustable or fixed output voltage options can be used to generate the Typical Performance Characteristics.
A
OUT=CIN

FIGURE 2-1: IQ vs. Ambient Temperature.

= 4.7 µF, L = 4.7 µH, V
FIGURE 2-4: I
(ADJ) = 1.8V, I
OUT
vs. Input Voltage.
Q
LOAD
= 100 mA,
FIGURE 2-2: Efficiency vs. Input Voltage
= 1.2V).
(V
OUT
FIGURE 2-3: Efficiency vs. Input Voltage (V
OUT
= 1.8V).
© 2007 Microchip Technology Inc. DS22042A-page 7
FIGURE 2-5: Efficiency vs. Output Load
= 1.2V).
(V
OUT
FIGURE 2-6: Efficiency vs. Output Load
= 1.8V).
(V
OUT
MCP1603
75
80
85
90
95
100
33.544.555.5
Input Voltage (V)
Efficiency (%)
V
OUT
= 2.4V
I
OUT
= 100 mA
I
OUT
= 500 mA
I
OUT
= 300 mA
85.0
87.5
90.0
92.5
95.0
97.5
100.0
3.5 3.75 4 4.25 4.5 4.75 5 5.25 5.5
Input Voltage (V)
Efficiency (%)
V
OUT
= 3.3V
I
OUT
= 100 mA
I
OUT
= 500 mA
I
OUT
= 300 mA
0.1
0.2
0.3
0.4
0.5
0.6
-40 -25 -10 5 20 35 50 65 80 95 110 125
Ambient Temperature (
o
C)
Line Regualtion (%/V)
I
OUT
= 100 mA
I
OUT
= 300 mA
V
OUT
= 1.8V
30
40
50
60
70
80
90
100
0.1 1 10 100 1000
Output Current (mA)
Efficiency (%)
V
OUT
= 2.4V
VIN = 4.2V
VIN = 2.7V
VIN = 3.6V
30
40
50
60
70
80
90
100
0.1 1 10 100 1000 Output Current (mA)
Efficiency (%)
V
OUT
= 3.3V
VIN = 4.2V
VIN = 3.6V
1.74
1.75
1.76
1.77
1.78
1.79
1.80
1.81
1.82
100 150 200 250 300 350 400 450 500
Output Current (mA)
Output Voltage (V)
TA = +125 oC
TA = - 40 oC
TA = +25 oC
TA = +90 oC
Typical Performance Curves (Continued)
Note: Unless otherwise indicated, VIN= SHDN =3.6V, C
T
= +25°C. Adjustable or fixed output voltage options can be used to generate the Typical Performance Characteristics.
A
OUT=CIN
= 4.7 µF, L = 4.7 µH, V
(ADJ) = 1.8V, I
OUT
LOAD
= 100 mA,
FIGURE 2-7: Efficiency vs. Input Voltage (V
= 2.4V).
OUT
FIGURE 2-8: Efficiency vs. Input Voltage
= 3.3V).
(V
OUT
FIGURE 2-10: Efficiency vs. Output Load (V
= 2.4V).
OUT
FIGURE 2-11: Efficiency vs. Output Load
= 3.3V).
(V
OUT
FIGURE 2-9: Line Regulation vs. Ambient Temperature (V
DS22042A-page 8 © 2007 Microchip Technology Inc.
OUT
= 1.8V).
FIGURE 2-12: Output Voltage vs. Load Current (V
OUT
= 1.8V).
MCP1603
1.95
2.00
2.05
2.10
2.15
2.20
-40 -25 -10 5 20 35 50 65 80 95 110 125
Ambient Temperature (
o
C)
Switching Frequency (MHz)
0.35
0.40
0.45
0.50
0.55
0.60
0.65
2.7 3.05 3.4 3.75 4.1 4.45 4.8 5.15 5.5
Input Voltage (V)
Switch Resistance (mΩ)
N-Channel
P-Channel
1.95
2.00
2.05
2.10
2.15
2.20
2.7 3.05 3.4 3.75 4.1 4.45 4.8 5.15 5.5
Input Voltage (V)
Switching Frequency (MHz)
0.3
0.4
0.5
0.6
0.7
0.8
0.9
-40 -25 -10 5 20 35 50 65 80 95 110 125
Ambient Temperature (
o
C)
Switch Resistance (mΩ)
N-Channel
P-Channel
Typical Performance Curves (Continued)
Note: Unless otherwise indicated, VIN= SHDN =3.6V, C
T
= +25°C. Adjustable or fixed output voltage options can be used to generate the Typical Performance Characteristics.
A
OUT=CIN
= 4.7 µF, L = 4.7 µH, V
(ADJ) = 1.8V, I
OUT
LOAD
= 100 mA,

FIGURE 2-13: Switching Frequency vs. Ambient Temperature.

FIGURE 2-14: Switch Resistance vs. Input Voltage.

FIGURE 2-16: Switching Frequency vs. Input Voltage.

FIGURE 2-17: Switch Resistance vs. Ambient Temperature.

FIGURE 2-15: Output Voltage Startup Waveform.

© 2007 Microchip Technology Inc. DS22042A-page 9

FIGURE 2-18: Heavy Load Switching Waveform.

MCP1603
Typical Performance Curves (Continued)
Note: Unless otherwise indicated, VIN= SHDN =3.6V, C T
= +25°C. Adjustable or fixed output voltage options can be used to generate the Typical Performance Characteristics.
A
OUT=CIN
= 4.7 µF, L = 4.7 µH, V
(ADJ) = 1.8V, I
OUT
LOAD
= 100 mA,

FIGURE 2-19: Light Load Switching Waveform.

FIGURE 2-20: Output Voltage Load Step Response vs. Time.

FIGURE 2-21: Output Voltage Line Step Response vs. Time.

DS22042A-page 10 © 2007 Microchip Technology Inc.

3.0 PIN DESCRIPTIONS

The descriptions of the pins are listed in Table 3-1.
TABLE 3-1: PIN FUNCTION TABLE
Pin No.
MCP1603
TSOT23
147VINPower Supply Input Voltage Pin 228GNDGround Pin 313SHDN 454V
531L — 2, 5, 6 NC No Connect — Exposed
MCP1603L
TSOT23
2x3 DFN
Pad
Symbol
Shutdown Control Input Pin
FB/VOUT
EP For the DFN package, the center exposed pad is a thermal
Feedback / Output Voltage Pin Switch Node, Buck Inductor Connection Pin
X
path to remove heat from the device. Electrically this pad is at ground potential and should be connected to GND
MCP1603
Description
3.1 Power Supply Input Voltage Pin )
(V
IN
Connect the input voltage source to VIN. The input source must be decoupled to GND with a 4.7 µF capacitor.
3.2 Ground Pin (GND)
Ground pin for the device. The loop area of the ground traces should be kept as minimal as possible.
3.3 Shutdown Control Input Pin
(SHDN
The SHDN pin is a logic-level input used to enable or disable the device. A logic high (> 45% of VIN) will enable the regulator output. A logic-low (< 15% of VIN) will ensure that the regulator is disabled.
)
3.4 Feedback / Output Voltage Pin (V
FB/VOUT
For adjustable output options, connect the center of the output voltage divider to the VFB/V output voltage options, connect the output directly to the V
FB/VOUT
pin.
)
pin. For fixed-
OUT
3.5 Switch Node, Buck Inductor Connection Pin (L
Connect the LX pin directly to the buck inductor. This pin carries large signal-level current; all connections should be made as short as possible.
)
X
3.6 Exposed Metal Pad (EP)
For the DFN package, connect the Exposed Pad to GND, with vias into the GND plane. This connection to the GND plane will aid in heat removal from the package.
© 2007 Microchip Technology Inc. DS22042A-page 11
MCP1603

4.0 DETAILED DESCRIPTION

4.1 Device Overview
The MCP1603 is a synchronous buck regulator that operates in a Pulse Frequency Modulation (PFM) mode or a Pulse Width Modulation (PWM) mode to maximize system efficiency over the entire operating current range. Capable of operating from a 2.7V to
5.5V input voltage source, the MCP1603 can deliver 500 mA of continuous output current.
When using the MCP1603, the PCB area required for a complete step-down converter is minimized since both the main P-Channel MOSFET and the synchro­nous N-Channel MOSFET are integrated. Also while in PWM mode, the device switches at a constant frequency of 2.0 MHz (typ) which allow for small filter­ing components. Both fixed and adjustable output voltage options are available. The fixed voltage options (1.2V, 1.5V 1.8V, 2.5V, 3.3V) do not require an external voltage divider which further reduces the required circuit board footprint. The adjustable output voltage options allow for more flexibility in the design, but require an external voltage divider.
Additionally the device features undervoltage lockout (UVLO), overtemperature shutdown, overcurrent protection, and enable/disable control.
4.2 Synchronous Buck Regulator
The MCP1603 has two distinct modes of operation that allow the device to maintain a high level of efficiency throughout the entire operating current and voltage range. The device automatically switched between PWM mode and PFM mode depending upon the output load requirements.
4.2.1 FIXED FREQUENCY, PWM MODE
During heavy load conditions, the MCP1603 operates at a high, fixed switching frequency of 2.0 MHz (typical) using current mode control. This minimizes output rip­ple (10 - 15 mV typically) and noise while maintaining high efficiency (88% typical with V V
= 1.8V, I
OUT
During normal PWM operation, the beginning of a switching cycle occurs when the internal P-Channel MOSFET is turned on. The ramping inductor current is sensed and tied to one input of the internal high-speed comparator. The other input to the high-speed compar­ator is the error amplifier output. This is the difference between the internal 0.8V reference and the divided­down output voltage. When the sensed current becomes equal to the amplified error signal, the high­speed comparator switches states and the P-Channel MOSFET is turned off. The N-Channel MOSFET is turned on until the internal oscillator sets an internal RS latch initiating the beginning of another switching cycle.
PFM-to-PWM mode transition is initiated for any of the following conditions:
• Continuous device switching
• Output voltage has dropped out of regulation
= 300 mA).
OUT
= 3.6V,
IN
4.2.2 LIGHT LOAD, PFM MODE
During light load conditions, the MCP1603 operates in a PFM mode. When the MCP1603 enters this mode, it begins to skip pulses to minimize unnecessary quies­cent current draw by reducing the number of switching cycles per second. The typical quiescent current draw for this device is 45 µA.
PWM-to-PFM mode transition is initiated for any of the following conditions:
• Discontinuous inductor current is sensed for a set duration
• Inductor peak current falls below the transition threshold limit
DS22042A-page 12 © 2007 Microchip Technology Inc.
MCP1603
4.3 Soft Start
The output of the MCP1603 is controlled during start­up. This control allows for a very minimal amount of
overshoot during start-up from VIN rising above
V
OUT
the UVLO voltage or SHDN being enabled.
4.4 Overtemperature Protection
Overtemperature protection circuitry is integrated in the MCP1603. This circuitry monitors the device junction temperature and shuts the device off, if the junction temperature exceeds the typical 150°C threshold. If this threshold is exceeded, the device will automatically restart once the junction temperature drops by approximately 10°C. The soft start is reset during an overtemperture condition.
4.5 Overcurrent Protection
Cycle-by-cycle current limiting is used to protect the MCP1603 from being damaged when an external short circuit is applied. The typical peak current limit is 860 mA. If the sensed current reaches the 860 mA limit, the P-Channel MOSFET is turned off, even if the output voltage is not in regulation. The device will attempt to start a new switching cycle when the internal oscillator sets the internal RS latch.
4.6 Enable/Disable Control
The SHDN pin is used to enable or disable the MCP1603. When the SHDN device is disabled. When pulled high the device is enabled and begins operation provided the input voltage is not below the UVLO threshold or a fault condition exists.
pin is pulled low, the
4.7 Undervoltage Lockout (UVLO)
The UVLO feature uses a comparator to sense the input voltage (V than the voltage necessary to properly operate the MCP1603, the UVLO feature will hold the converter off. When V UVLO is released and soft start begins. Hysteresis is built into the UVLO circuit to compensate for input impedance. For example, if there is any resistance between the input voltage source and the device when it is operating, there will be a voltage drop at the input to the device equal to I is 140 mV.
rises above the necessary input voltage, the
IN
) level. If the input voltage is lower
IN
x RIN. The typical hysteresis
IN
© 2007 Microchip Technology Inc. DS22042A-page 13
MCP1603
R
BOT
R
TOP
V
FB
V
OUTVFB
-----------------------------
⎝⎠
⎛⎞
×=
Example:
R
TOP
=200kΩ
V
OUT
=1.0V
V
FB
=0.8V
R
BOT
=200kΩ x (0.8V/(1.0V - 0.8V))
R
BOT
=800kΩ
(Standard Value = 787 kΩ)
I
CIN RMS,
I
OUT MAX,
V
OUTVINVOUT
()×
V
IN
------------------------------------------------------
⎝⎠
⎜⎟
⎛⎞
×=
Δ
V
OUT
Δ
ILESR
×
Δ
I
L
8fC
××
---------------------+=

5.0 APPLICATION INFORMATION

5.1 Typical Applications
The MCP1603 500 mA synchronous buck regulator operates over a wide input voltage range (2.7V to 5.5V) and is ideal for single-cell Li-Ion battery powered applications, USB powered applications, three cell NiMH or NiCd applications and 3V or 5V regulated input applications. The 5-lead TSOT and 8-lead 2x3 DFN packages provide a small footprint with minimal external components.
5.2 Fixed Output Voltage Applications
Typical Application Circuit shows a fixed MCP1603
in an application used to convert three NiMH batteries into a well regulated 1.8V @ 500 mA output. A 4.7 µF input capacitor, 4.7 µF output capacitor, and a 4.7 µH inductor make up the entire external component solu­tion for this application. No external voltage divider or compensation is necessary. In addition to the fixed
1.8V option, the MCP1603 is also available in 1.2V,
1.5V, 2.5V, or 3.3V fixed voltage options.
5.3 Adjustable Output Voltage Applications
For adjustable output applications, an additional R-C compensation network is necessary for control loop stability. Recommended values for any output voltage are:
R
COMP
C
COMP
Refer to Figure 6-2 for proper placement of R C
COMP
=4.99kΩ =33pF
.
COMP
and
5.4 Input Capacitor Selection
The input current to a buck converter, when operating in continuous conduction mode, is a squarewave with a duty cycle defined by the output voltage (V input voltage (V undesirable input voltage transients, the input capacitor should be a low ESR type with an RMS current rating given by Equation 5.5. Because of their small size and low ESR, ceramic capacitors are often used. Ceramic material X5R or X7R are well suited since they have a low temperature coefficient and acceptable ESR.
) relationship of V
IN
OUT/VIN
. To prevent
EQUATION 5-2:
OUT
) to
When the desired output for a particular application is not covered by the fixed voltage options, an adjustable MCP1603 can be used. The circuit listed in Figure 6-2 shows an adjustable MCP1603 being used to convert a 5V rail to 1.0V @ 500 mA. The output voltage is adjust­able by using two external resistors as a voltage divider. For adjustable-output voltages, it is recommended that the top resistor divider value be 200 kΩ. The bottom resistor value can be calculated using the following equation:
EQUATION 5-1:
Table 5-1 contains the recommend range for the input
capacitor value.
5.5 Output Capacitor Selection
The output capacitor helps provide a stable output voltage during sudden load transients, smooths the current that flows from the inductor to the load, and reduces the output voltage ripple. Therefore, low ESR capacitors are a desirable choice for the output capac­itor. As with the input capacitor, X5R and X7R ceramic capacitors are well suited for this application.
The output ripple voltage is often a design specifica­tion. A buck converters’ output ripple voltage is a function of the charging and discharging of the output capacitor and the ESR of the capacitor. This ripple voltage can be calculated by Equation 5-3.
EQUATION 5-3:
DS22042A-page 14 © 2007 Microchip Technology Inc.
MCP1603
ΔI
L
V
OUT
F
SW
L×
-------------------
1
V
OUT
V
IN
-------------
⎝⎠
⎛⎞
×=
Where:
F
SW
= Switching Frequency
V
OUTIOUT
×
Efficiency
-------------------------------
⎝⎠
⎛⎞
V
OUTIOUT
×() P
Diss
=
Table 5-1 contains the recommend range for the output
capacitor value.

TABLE 5-1: CAPACITOR VALUE RANGE

C
IN
Minimum 4.7 µF 4.7 µF
Maximum 22 µF
C
OUT
5.6 Inductor Selection
When using the MCP1603, the inductance value can range from 3.3 µH to 10 µH. An inductance value of
4.7 µH is recommended to achieve a good balance between converter load transient response and mini­mized noise.
The value of inductance is selected to achieve a desired amount of ripple current. It is reasonable to assume a ripple current that is 20% of the maximum load current. The larger the amount of ripple current allowed, the larger the output capacitor value becomes to meet ripple voltage specifications. The inductor ripple current can be calculated according to the follow­ing equation.
EQUATION 5-4:
TABLE 5-2: MCP1603 RECOMMENDED
INDUCTORS
Part
Number
Coiltronics
SD3110 3.3 0.195 0.81 3.1x3.1x1.0 SD3110 4.7 0.285 0.68 3.1x3.1x1.0 SD3110 6.8 0.346 0.58 3.1x3.1x1.0 SD3812 3.3 0.159 1.40 3.8x3.8x1.2 SD3812 4.7 0.256 1.13 3.8x3.8x1.2 SD3812 6.8 0.299 0.95 3.8x3.8x1.2
Würth Elektronik
WE-TPC Type XS
WE-TPC Type XS
WE-TPC
Type S
WE-TPC
Type S
Sumida
CMD4D06 3.3 0.174 0.77 3.5x4.3x0.8 CMD4D06 4.7 0.216 0.75 3.5x4.3x0.8 CMD4D06 6.8 0.296 0.62 3.5x4.3x0.8
Value
(µH)
®
3.3 0.225 0.72 3.3x3.5x0.95
4.7 0.290 0.50 3.3x3.5x0.95
4.7 0.105 0.90 3.8x3.8x1.65
6.8 0.156 0.75 3.8x3.8x1.65
®
DCR
Ω
(max)
®
I
SAT
(A)
Size
WxLxH (mm)
When considering inductor ratings, the maximum DC current rating of the inductor should be at least equal to the maximum load current, plus one half the peak-to­peak inductor ripple current (1/2 * ΔI resistance adds to the total converter power loss. An inductor with a low DC resistance allows for higher converter efficiency.
). The inductor DC
L
5.7 Thermal Calculations
The MCP1603 is available in two different packages (TSOT-23 and 2x3 DFN). By calculating the power dissipation and applying the package thermal resistance, (θ estimated. The maximum continuous junction temperature rating for the MCP1603 is +125°C.
To quickly estimate the internal power dissipation for the switching buck regulator, an empirical calculation using measured efficiency can be used. Given the measured efficiency, the internal power dissipation is estimated by:
EQUATION 5-5:
The difference between the first term, input power dissipation, and the second term, power delivered, is the internal power dissipation. This is an estimate assuming that most of the power lost is internal to the MCP1603. There is some percentage of power lost in the buck inductor, with very little loss in the input and output capacitors.
), the junction temperature is
JA
© 2007 Microchip Technology Inc. DS22042A-page 15
MCP1603
V
IN
SHDN
GND
V
FB
L
X
VIN
2.7V To 4.5V
V
OUT
1.8V @ 500 mA
C
OUT
4.7 µF
C
IN
4.7 µF
L
1
4.7 µH
5.8 PCB Layout Information
Good printed circuit board layout techniques are important to any switching circuitry and switching power supplies are no different. When wiring the high current paths, short and wide traces should be used. This high current path is shown with red connections in
Figure 5-1. The current in this path is switching.

FIGURE 5-1: PCB High Current Path.

Therefore, it is important that the components along the high current path should be placed as close as possible to the MCP1603 to minimize the loop area.
The feedback resistors and feedback signal should be routed away from the switching node and this switching current loop. When possible ground planes and traces should be used to help shield the feedback signal and minimize noise and magnetic interference.
DS22042A-page 16 © 2007 Microchip Technology Inc.

6.0 TYPICAL APPLICATION CIRCUITS

V
IN
SHDN
GND
V
FB
L
X
VIN
3.0V To 4.2V
V
OUT
1.5V @ 500 mA
C
OUT
4.7 µF
C
IN
4.7 µF
L
1
4.7 µH
R
TOP
200 kΩ
R
BOT
787 kΩ
V
IN
SHDN
GND
V
FB
L
X
VIN
5.0V
V
OUT
1.0V @ 500 mA
C
OUT
4.7 µF
C
IN
4.7 µF
L
1
4.7 µH
R
COMP
4.99 kΩ
C
COMP
33 pF
V
IN
SHDN
GND
V
FB
L
X
VIN
2.7V To 4.5V
V
OUT
1.2V @ 500 mA
C
OUT
4.7 µF
C
IN
4.7 µF
L
1
4.7 µH
l
FIGURE 6-1: Single Li-Ion to 1.5V @ 500 mA Application.
MCP1603
FIGURE 6-2: 5V to 1.0V @ 500 mA Application.
FIGURE 6-3: 3 NiMH Batteries to 1.2V @ 500 mA Application.9
© 2007 Microchip Technology Inc. DS22042A-page 17
MCP1603
8-Lead 2x3 DFN
Example
:
XXX YWW
NNN
Legend: XX...X Customer-specific information
Y Year code (last digit of calendar year) YY Year code (last 2 digits of calendar year) WW Week code (week of January 1 is week ‘01’) NNN Alphanumeric traceability code Pb-free JEDEC designator for Matte Tin (Sn) * This package is Pb-free. The Pb-free JEDEC designator ( )
can be found on the outer packaging for this package.
Note: In the event the full Microchip part number cannot be marked on one line, it will
be carried over to the next line, thus limiting the number of available characters for customer-specific information.
5-Lead TSOT
XXNN
Example
ET25
AFM 711
25
Part Number
Marking
Code
MCP1603-120I/MC AFM MCP1603-150I/MC AFK MCP1603-180I/MC AFJ MCP1603-250I/MC AFG MCP1603-330I/MC AFA MCP1603-ADJI/MC AFQ
Part Number
Marking
Code
MCP1603T-120I/OS ETNN MCP1603T-150I/OS EUNN MCP1603T-180I/OS EVNN MCP1603T-250I/OS EWNN MCP1603T-330I/OS EXNN MCP1603T-ADJI/OS EYNN
Part Number
Marking
Code
MCP1603LT-120I/OS FMNN MCP1603LT-150I/OS FKNN MCP1603LT-180I/OS EJNN MCP1603LT-250I/OS FGNN MCP1603LT-330I/OS FANN MCP1603LT-ADJI/OS FQNN

7.0 PACKAGING INFORMATION

7.1 Package Marking Information (Not to Scale)
3
e
DS22042A-page 18 © 2007 Microchip Technology Inc.
3
e
8-Lead Plastic Dual Flat, No Lead Package (MC) – 2x3x0.9 mm Body [DFN]
Notes:
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. Package may have one or more exposed tie bars at ends.
3. Package is saw singulated.
4. Dimensioning and tolerancing per ASME Y14.5M. BSC: Basic Dimension. Theoretically exact value shown without tolerances. REF: Reference Dimension, usually without tolerance, for information purposes only.
Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
Units MILLIMETERS
Dimension Limits MIN NOM MAX Number of Pins N 8 Pitch e 0.50 BSC Overall Height A 0.80 0.90 1. 00 Standoff A1 0.00 0.02 0.05 Contact Thickness A3 0.20 REF Overall Length D 2.00 BSC Overall Width E 3.00 BSC Exposed Pad Length D2 1.30 1.75 Exposed Pad Width E2 1.50 1.90 Contact Width b 0.18 0.25 0.30 Contact Length L 0.30 0.40 0.50 Contact-to-Exposed Pad K 0.20
D
N
E
NOTE 1
1
2
EXPOSED PAD
NOTE 1
2
1
D2
K
L
E2
N
e
b
A3 A1
A
NOTE 2
BOTTOM VIEW
TOP VIEW
Microchip Technology Drawing C04-123B
MCP1603
© 2007 Microchip Technology Inc. DS22042A-page 19
MCP1603
5-Lead Plastic Thin Small Outline Transistor (OS) [TSOT]
Notes:
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.15 mm per side.
3. Dimensioning and tolerancing per ASME Y14.5M. BSC: Basic Dimension. Theoretically exact value shown without tolerances.
REF: Reference Dimension, usually without tolerance, for information purposes only.
Note: For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
Units MILLIMETERS
Dimension Limits MIN NOM MAX Number of Leads N 5 Lead Pitch e 0.95 BSC Outside Lead Pitch e1 1.90 BSC Overall Height A 1.10 Molded Package Thickness A2 0.70 0.90 1.00 Standoff A1 0.00 0.10 Overall Width E 2.80 BSC Molded Package Width E1 1.60 BSC Overall Length D 2.90 BSC Foot Length L 0.30 0.45 0.60 Footprint L1 0.60 REF Foot Angle φ Lead Thickness c 0.08 0.20 Lead Width b 0.30 0.50 Mold Draft Angle Top α 10° 12° Mold Draft Angle Bottom β 10° 12°
N
b
E
E1
NOTE 1
D
e1
e
1
2
3
A
A1
A2
c
L1
L
φ
β
α
Microchip Technology Drawing C04-128B
DS22042A-page 20 © 2007 Microchip Technology Inc.
APPENDIX A: REVISION HISTORY
Revision A (May 2007)
• Original Release of this Document.
MCP1603
© 2007 Microchip Technology Inc. DS22042A-page 21
MCP1603
NOTES:
DS22042A-page 22 © 2007 Microchip Technology Inc.
PRODUCT IDENTIFICATION SYSTEM
Device: MCP1603: 2.0 MHz, 500 mA Buck Regulator
TSOT Pin Config. Designator *
Blank = Standard pinout L = Alternate pinout * Refer to Package Types for an explanation regarding the function of the device pins.
Tape and Reel: T = Tape and Reel
Blank = Tube
Voltage Option: ADJ = Adjustable
120 = 1.20V “Standard” 150 = 1.50V “Standard” 180 = 1.80V “Standard” 250 = 2.50V “Standard” 330 = 3.30V “Standard”
Temperature: I = -40°C to +85°C
Package Type: MC = Plastic Dual-Flat No-Lead Package (MC), 8-Lead
OS = Plastic Thin Small Outline Transistor (OS), 5-Lead
PART NO. XXXX
Tap e Voltage
Option
Device
and Reel
X
Tem p.XXPackage
X
TSOT
Config.
Examples: 8-Lead DFN:
a) MCP1603-120I/MC: 1.20V Buck Reg.,
8LD-DFN pkg.
b) MCP1603-150I/MC: 1.50V Buck Reg.,
8LD-DFN pkg.
c) MCP1603-180I/MC: 1.80V Buck Reg.,
8LD-DFN pkg.
d) MCP1603-250I/MC: 2.50V Buck Reg.,
8LD-DFN pkg.
e) MCP1603-330I/MC: 3.30V Buck Reg.,
8LD-DFN pkg.
5-Lead TSOT:
a) MCP1603T-120I/OS: 1.20V Buck Reg.,
5LD-TSOT pkg.
b) MCP1603T-180I/OS: 1.80V Buck Reg.,
5LD-TSOT pkg.
c) MCP1603T-250I/OS: 2.50V Buck Reg.,
5LD-TSOT pkg.
d) MCP1603T-330I/OS: 3.30V Buck Reg.,
5LD-TSOT pkg.
e) MCP1603T-ADJI/OS: Adj. Buck Reg.,
5LD-TSOT pkg.
f) MCP1603LT-250I/OS:2.50V Buck Reg.,
5LD-TSOT pkg.
g) MCP1603LT-ADJI/OS:Adj. Buck Reg.,
5LD-TSOT pkg.
/
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
MCP1603
© 2007 Microchip Technology Inc. DS22042A-page 23
MCP1603
NOTES:
DS22042A-page 24 © 2007 Microchip Technology Inc.
Note the following details of the code protection feature on Microchip devices:
Microchip products meet the specification contained in their particular Microchip Data Sheet.
Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions.
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
Microchip is willing to work with the customer who is concerned about the integrity of their code.
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer’s risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights.
Trademarks
The Microchip name and logo, the Microchip logo, Accuron, dsPIC, K
EELOQ, KEELOQ logo, microID, MPLAB, PIC,
PICmicro, PICSTART, PRO MATE, rfPIC and SmartShunt are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.
AmpLab, FilterLab, Linear Active Thermistor, Migratable Memory, MXDEV, MXLAB, SEEVAL, SmartSensor and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A.
Analog-for-the-Digital Age, Application Maestro, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB, In-Circuit Serial Programming, ICSP, ICEPIC, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, PICkit, PICDEM, PICDEM.net, PICLAB, PICtail, PowerCal, PowerInfo, PowerMate, PowerTool, REAL ICE, rfLAB, Select Mode, Smart Serial, SmartTel, Total Endurance, UNI/O, WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries.
SQTP is a service mark of Microchip Technology Incorporated in the U.S.A.
All other trademarks mentioned herein are property of their respective companies.
© 2007, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved.
Printed on recycled paper.
Microchip received ISO/TS-16949:2002 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company’s quality system processes and procedures are for its PIC devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001:2000 certified.
®
MCUs and dsPIC® DSCs, KEELOQ
®
code hopping
© 2007 Microchip Technology Inc. DS22042A-page 25
WORLDWIDE SALES AND SERVICE
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DS22042A-page 26 © 2007 Microchip Technology Inc.
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