View MAX1809EVKIT_376999.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

19-2156; Rev 0; 9/01
MAX1809 Evaluation Kit
General Description
The MAX1809 evaluation kit (EV kit) provides a +1.1V output voltage from a +3V to +5.5V input source. It sources and sinks up to 3A of current. The MAX1809 is a step-down switching regulator with an internal synchronous-rectifier that operates up to 1MHz, minimizing external components. The device features a resistorprogrammable, fixed off-time current-mode operation for superior load- and line-transient response, and achieves efficiencies up to 93%. o 3A Output Current o Up to 1MHz Switching Frequency o Up to 93% Efficiency o Synchronous Rectification for Improved Efficiency o Output Voltage: +1.1V to VIN Adjustable o +3V to +5.5V Input Voltage Range o Less than 1A Typical IC Shutdown Current o Surface-Mount Construction o Fully Assembled and Tested
Features
Evaluates: MAX1809
Ordering Information
PART MAX1809EVKIT TEMP. RANGE 0C to +70C IC PACKAGE 16 QSOP
Component List
DESIGNATION C1 C2, C9 C3 C4 QTY 1 0 1 1 DESCRIPTION 33F, 6.3V, X5R ceramic capacitor TDK C3225XR0J336V Not installed 270F, 2V, 15m ESR SP capacitor Panasonic EEFUE0D271R 0.01F, 50V, X7R ceramic 2.2F, 10V, X5R ceramic capacitor Taiyo Yuden LMK212BJ225MG TDK C2012X5R1A225M 1F, 10V, X7R ceramic capacitor Taiyo Yuden LMK212BJ105MG Murata GRM40X7R105K010 TDK C2012X5R1C105K 1000pF, 50V, C0G ceramic capacitors Not installed Diode Diodes Inc. 1N4148W Fairchild MMSD4148 General Semiconductor 1N4148W L1 1 DESIGNATION JU1, JU2 JU3 QTY 2 0 DESCRIPTION 2-pin headers Not installed 1H, 3A inductor Sumida 4762-T072 (CDRH6D28 type) Toko A920CY-1R0M (D62CB type) 10k 1% resistors 10 5%resistor 1M 5% resistor 130k 1% resistor 0.012 1%, 0.5W sense resistor Vishay Dale WSL-2010-R012F IRC LRC-LR2010-01-R012-F 100 5% resistor Not installed MAX1809EEE (16-QSOP) Shunts for JU1 and JU2
R1, R2 R3 R4 R5
2 1 1 1
C5
1
C6
1
R6 R7 R8 U1 None
1 1 0 1 2
C7, C8 D1, D2
2 0
D3
1
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
MAX1809 Evaluation Kit Evaluates: MAX1809
Component Suppliers
SUPPLIER Diodes Inc. Fairchild General Semiconductor IRC Murata Nihon Panasonic Sumida Taiyo Yuden TDK Toko PHONE 805-446-4800 888-522-5372 760-804-9258 361-992-7900 770-436-1300 661-867-2555 201-392-7522 847-545-6700 800-348-2496 847-803-6100 847-297-0070 FAX 805-381-3899 -- 760-804-9259 361-992-3377 770-436-3030 661-867-2698 201-392-4441 847-545-6720 847-925-0899 847-390-4405 847-699-1194 Closed (Default)
Table 1. Jumper JU1 Functions
SHUNT LOCATION Open SHDN PIN Connected to GND through 1M (R4) Connected to VIN MAX1809 OUTPUT Shutdown mode, VOUT = 0 MAX1809 enabled, VOUT = +1.1V.
Output Voltage Selection
The MAX1809 EV kit is shipped with the output voltage set to +1.1V. To change the output voltage, follow the configurations stated in Table 2.
Vishay Dale 402-564-3131 402-563-6296 Note: Please indicate that you are using the MAX1809 when contacting these suppliers
Table 2. Setting the MAX1809 Output Voltage
JU2 Closed (Default) Closed CONDITION R7 = 100, R8 = open R7 = 10k, R8 = installed R7 = 100, R8 = open; external voltage applied to the pads labeled EXTREF and AGND R7 = 100, R8 = open; external voltage applied to the pads labeled VDD and AGND OUTPUT VOLTAGE VOUT = +1.1V VOUT = +1.1V x (1 + R7/R8)
Quick Start
The MAX1809 EV kit is a fully assembled and tested surface-mount board. Follow the steps below to verify board operation. Do not turn on the power supply until all connections are completed. 1) Verify that a shunt is on JU1 (shutdown disabled) to enable operation and on JU2 to set the output voltage to +1.1V. 2) Connect a voltmeter and load (if any) to VOUT and GND. 3) Connect a +3V to +5.5V supply to the pads marked VIN and GND. 4) Turn on the power and verify that the output voltage is +1.1V. 5) Refer to the Output Voltage Selection section to modify the board for a different output voltage.
Open
VOUT = VEXTREF
Open
VOUT = VDD/2
Detailed Description
The MAX1809 EV kit provides a +1.1V output voltage from a +3V to +5.5V input voltage. It sources or sinks up to 3A of output current. Continuous operation at 3A with high ambient temperatures may be limited due to thermal considerations (see the MAX1809 data sheet).
Jumper Selection
Jumper JU1 selects the shutdown mode of the MAX1809. Table 1 lists the jumper options. Jumper JU2 connects EXTREF to REF, setting the output voltage of the MAX1809 to +1.1V. Refer to the Output Voltage Selection section.
2
When the shunt at JU2 is removed, observe the voltage limits on EXTREF as recommended in the MAX1809 data sheet. Failure to observe these limits can cause the part to enter abnormal operating conditions and might cause the part to be damaged. For output voltages above +1.6V, replace capacitor C3 with a higher voltage rated capacitor. R7 is set at 100 for configurations that do not use R8 to adjust the output voltage. This 100 allows the MAX1809 to power up into a sinking current mode. Refer to the MAX1809 data sheet for a detailed description of this function.
_______________________________________________________________________________________
MAX1809 Evaluation Kit
Note: The switching frequency of the MAX1809 EV kit is 600kHz when the input voltage is +5V and the output voltage is +1.1V. This frequency will change when the input or output voltages change. When operated from a +3.3V input voltage, the switching frequency will be 450kHz. Do not operate the MAX1809 above 1MHz. To set the switching frequency, change the tOFF resistor (R5) and the inductor. Refer to the MAX1809 data sheet to determine the values. In the sinking-mode test setup (Figure 2), beware of back-biasing the EV kit with too high a voltage during the turn-on sequence. The supply to the EV kit (VDC1) must be powered on before the supply is connected to the load (VDC2). Failure to do so will result in permanent damage to the evaluation kit. Also, do not source current to the load supply (VDC2) as it can damage that supply. Follow these procedures when conducting a sinkingmode test: 1) Disconnect the load from the output of the MAX1809 EV kit. 2) Connect a preload across VIN and GND. Use the following equation to determine the minimum required preload current. V Ipreload > 3A OUT VIN 3) Power up the MAX1809 EV kit. 4) Set the load at the highest impedance. 5) Set the load supply (VDC2) to the same voltage as the output of the MAX1809 EV kit. 6) Connect the load to the output of the MAX1809 EV kit (VOUT and GND). 7) Adjust the load and increase VDC2 until the desired sinking current is reached. Before powering down the MAX1809, disconnect the load from the output of the MAX1809 EV kit to prevent driving a high voltage into the output of the MAX1809 while it is off.
Evaluates: MAX1809
Test Setup
In applications that require active termination, the MAX1809 is required to both source and sink current. Figures 1 and 2 below show how to set up the MAX1809 EV kit for sourcing and sinking current. For sourcing-mode test setup (Figure 1), connect an external load to the pads labeled VOUT and GND.
VDC
LOAD (SOURCING) ISOURCE
Figure 1. Test Setup (Sourcing)
Load Transient Experiment
VDC1 VDC2
PRE-LOAD
LOAD (SINKING) ISINK
IPRE-LOAD
Figure 2. Test Setup (Sinking)
One interesting experiment is to subject the output to fast load transients. Most benchtop electronic loads intended for power-supply testing lack the ability to subject the DC-DC converter to ultra-fast load transients. Emulating the termination supply's fast di/dt requires at least 10A/s load transients. An easy method for generating such an abusive load transient is to solder a MOSFET, such as an MTP3055 or 12N05, directly across VOUT and GND. Then drive its gate with a strong pulse generator at a low duty cycle (=10%) to minimize heat stress in the MOSFET. Adjust the highlevel output voltage of the pulse generator to vary the load current. Alternatively, control the load current with a load resistor in series with the MOSFET's drain, and drive the MOSFET fully on. Remember to include the expected on-resistance of the MOSFET in the load resistor calculation.
3
_______________________________________________________________________________________
MAX1809 Evaluation Kit Evaluates: MAX1809
To perform a fast transient test that goes from sourcing mode to sinking mode and back, first arrange the setup as in the sinking mode. Add the dummy MOSFET from VOUT to GND as described in the previous paragraph. Power up the MAX1809 and set the sinking current to the desired level, then use the pulse generator to pull the appropriate sourcing current through the dummy MOSFET. In this situation, the dummy MOSFET will be sinking both the external sinking current and the sourcing current from the output of the MAX1809. As an example, if the transient is required to go from -1A (sinking) to +2A (sourcing), then the dummy MOSFET needs to sink +3A when it is turned on. Figure 3 illustrates this setup.
VDC2 SINK LOAD
Note: Do not place a current meter in the load path to determine the load current because the additional resistance and inductance will interfere with fast load transients. It is best to observe the inductor current with a calibrated AC-current probe, such as a Tektronix AM503. In the buck topology, the load current is equal to the average value of the inductor current. The MAX1809 EV kit is optimized to handle load transients from -2A to +2A. For load steps that are larger than 4A total, refer to the MAX1809 data sheet to calculate the required inductance and output capacitance.
Optimizing for +3.3V Input Supplies
The components selected for the MAX1809 EV kit are optimized for an input voltage of +5V. When operating from a +3.3V input supply, change L1 to 0.68H (Murata LQS66CR68M04M00) and R5 to 73.2k 1%. This increases the switching frequency to 810MHz when sourcing current and to 970MHz when sinking current.
1A L LX VOUT
Improving Efficiency
MAX1809
COUT 0A-3A GND SOURCE LOAD
The MAX1809 EV kit has footprints for Schottky diodes across the internal PMOS and NMOS. For lowest cost implementation, these Schottky diodes can be omitted. For maximum efficiency, place a 0.5A low-leakage Schottky, such as Nihon EP5Q03L, in positions D1 and D2.
Figure 3. Load Transient Setup
4
_______________________________________________________________________________________
MAX1809 Evaluation Kit Evaluates: MAX1809
+3V TO +5.5V VIN C1 33F 2 IN 12 C5 2.2F JU1 1 R4 1M SS 5 C4 0.01F EXTREF R5 130k 1% VDD C7 1000pF R1 10k JU2 C8 1000pF R2 10k GND 11 GND 9 6 SS U1 SHDN 15 PGND 13 PGND VCC 4 IN 16 LX LX 14 3 LX D2 OPEN D1 OPEN R6 0.012 1% C3 270F 2V
GND
R3 10
L1 1H
VOUT
C2 OPEN
GND
MAX1809
EXTREF FB
C9 OPEN 8 D3 SS 10 C6 1.0F
R7 100
JU3 OPEN
R8 OPEN
7
TOFF
REF
GND
Figure 4. MAX1809 EV Kit Schematic
_______________________________________________________________________________________
5
MAX1809 Evaluation Kit Evaluates: MAX1809
1.0"
1.0"
Figure 5. MAX1809 EV Kit Component Placement Guide-- Component Side
Figure 6. MAX1809 EV Kit PC Board Layout--Component Side
1.0"
1.0"
Figure 7. MAX1809 EV Kit PC Board Layout--Solder Side
Figure 8. MAX1809 EV Kit Component Placement Guide-- Solder Side
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
6 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

▲Up To Search▲

Price & Availability of MAX1809EVKIT

	To Download MAX1809EVKIT Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .