Alice Chen
| Picture | Part Number | Manufacturer | Stock | Action |
|---|---|---|---|---|
 | LMZM23601SILR | Texas Instruments | 5,540 | |
 | TPS5430DDAR | Texas Instruments | 4,010 |
No. LMZM23601SILR is the adjustable option, supporting 1.2–15 V output subject to the input/output operating constraints. LMZM23601V5SILR is the fixed 5 V orderable option. The adjustable device uses a feedback divider; the fixed-output connection shown on the datasheet cover must not be copied without checking the suffix.
No. Pins 8, 9 and 10 must remain floating. They expose internal VCC, BOOT and SW nodes respectively. Grounding them can interfere with operation or damage the device. The dedicated thermal pad is internally connected to ground and is the appropriate electrical and thermal connection to the PCB ground plane.
No. The datasheet provides CISPR 11 radiated-emission examples for specified evaluation-board arrangements, with 24 V input, 5 V output and 1 A load. Those results do not certify an arbitrary product, cable configuration or enclosure. Check the applicable product standard and measure the final assembly.
By Alice Chen | YG GROUP
The LMZM23601SILR is an adjustable, integrated-inductor buck module for 4–36 V inputs and up to 1 A output. Its 3.8 × 3.0 mm package can simplify a compact power supply, but the total PCB solution still includes capacitors, feedback components and thermal copper. A useful comparison with a discrete buck therefore checks the complete layout and the stated EMI and thermal test conditions, rather than treating package area as system performance.
The integrated inductor changes the engineering workload as much as the component count. It avoids selecting and routing an external power inductor, and it contains the switching-node connection inside the module. That can make a small sensor board easier to implement. It does not remove the external input capacitor, the output capacitor or the path through which the board supplies switching current. Figure 1 makes that distinction explicit.
A discrete design gives the engineer more freedom over the inductor, controller operating point and placement. That freedom can help when a board has unusual height restrictions, a demanding load transient or a specific thermal arrangement. It also creates additional decisions and more opportunities for a poor layout. Neither approach wins all three comparisons in the title without a defined board and operating point.
No. A thermal metric describes a stated test arrangement, not every board. Establish losses at the actual input, output and load, then evaluate copper, ambient temperature, airflow and nearby heat sources. The module rating alone does not establish continuous full-load operation in a sealed hot enclosure.
Figure 1. Conceptual power paths: integration removes the external inductor from the module BOM, while both architectures retain an input capacitor switching-current loop. This is not an EMI spectrum or an area-scaled PCB layout. Source: TI SNVSAQ4C and TPS5430 product information.
LMZM23601SILR is the adjustable option. The fixed 3.3 V and 5 V variants contain V3 or V5 in their order codes. Confusing these variants changes the feedback circuit and can produce the wrong output. The adjustable version supports 1.2–15 V output, with additional input/output restrictions described in the application section. Its typical internal switching frequency is 1 MHz; the fixed-output versions use 750 kHz. A single frequency value should therefore not be assigned to every orderable device.
Table 1. Module operating and package boundaries | Source: manufacturer documents in References; assumptions and operating conditions are stated in the table or adjacent text. Compiled / calculated by: YG GROUP.
| Check | LMZM23601SILR evidence | Implication for a comparison |
|---|---|---|
| Input range | 4–36 V recommended operation | Include supply tolerance and transient protection; 40 V absolute maximum is not an operating target |
| Output | Adjustable 1.2–15 V; up to 1 A | Confirm the output configuration and thermal conditions |
| Package body | 3.8 × 3.0 mm MicroSiP | Package area excludes capacitors, resistors and copper |
| Inductor | Integrated | No external power-inductor footprint is required |
| Feedback | External divider on FB pin 7 | Include divider area and quiet routing in the solution |
For a fair area estimate, draw the actual component courtyard, input and output capacitor placements, feedback divider and required copper on the intended layer stack. Apply the same rules to the discrete design. Comparing the module body against a complete discrete circuit exaggerates the saving. Conversely, including a generous thermal copper region only for the module can disguise a legitimate packaging benefit.
TI shows CISPR 11 radiated-emission results at 24 V input, 5 V output and 1 A load. Figure 6-7 uses the evaluation-module layout with three additional 100 pF input capacitors; Figure 6-8 identifies the default evaluation-module BOM and a top ground plane. These are documented examples of particular hardware arrangements. They are useful starting points for layout decisions, not a certificate for a new end product.
The input capacitor must sit directly between VIN pin 3 and GND pin 1. Its high-frequency current path should be short and compact. The integrated inductor reduces one exposed switching connection, but a long input loop, a poorly connected return plane or an attached cable can still create an emissions problem. The final result also depends on the measurement setup and applicable product standard. Do not rename the published CISPR 11 plots as CISPR 32 data.
Changing the operating mode can change light-load behavior. MODE/SYNC tied low selects automatic PFM/PWM operation; tied high selects forced PWM. An external synchronization signal provides another option within the specified conditions. This pin must not float. Select a mode for the actual load profile, then include it in the final-board EMI test description.
Figure 2 shows the adjustable-device connections. The input and output capacitors connect to the ground network, and the thermal pad connects to the ground plane. Pins 8–10 are different: they expose internal VCC, BOOT and SW nodes and must remain floating. They must not be treated as extra ground pads or tied together to create a larger heat-spreading surface.
Figure 2. Adjustable-device connection concept, including the input and output capacitors, feedback divider and grounded thermal pad. Pins 8–10 remain open. Pin placement is functional, not a manufacturing land pattern; component values depend on the selected output. Source: TI SNVSAQ4C, pages 4, 24–25 and 35–37.
The datasheet recommends a high-quality input capacitor and gives output-capacitance requirements that change with output voltage. For example, the typical 5 V application uses 22 µF output capacitance, while the low-voltage cases need different values. Evaluate effective ceramic capacitance at the operating voltage rather than relying only on the printed nominal value. Keep the FB node small and away from the switching-current paths; connect its divider return to a quiet ground reference.
Table 2. Required feedback and ground connections | Source: manufacturer documents in References; assumptions and operating conditions are stated in the table or adjacent text. Compiled / calculated by: YG GROUP.
| Connection | Required treatment | Error to avoid |
|---|---|---|
| VIN 3 / GND 1 | Place the input bypass directly across these pins | Routing the capacitor through a long supply or return trace |
| VOUT 6 / FB 7 | Output capacitor plus adjustable feedback divider | Copying a fixed-variant FB connection |
| DNC 8–10 | Leave open | Grounding internal VCC, BOOT or SW access pins |
| Thermal pad | Connect to the ground plane | Assuming all nearby package pads are ground |
At a known operating point, a first estimate is P_loss = P_out × (1/η − 1). The efficiency used in that calculation must match the input, output, load and mode. A peak efficiency from another point cannot establish enclosure temperature. The source thermal metrics and derating curves likewise apply to their stated arrangements; they do not support a universal ambient-temperature limit for every board.
For the module and the discrete circuit, establish an identical load, ambient condition and airflow assumption. Examine heat spreading through the assembled PCB and the influence of adjacent components. Then measure temperatures and regulation on the intended board, including the worst supply and duty cycle. Thermal shutdown is a protection mechanism, not the normal design point for continuous operation.
TPS5430DDAR provides a concrete external-inductor comparison: its family is rated for 5.5–36 V input, 3 A output and 500 kHz switching. It is a different current class, so its package or output capability cannot establish a matched area or efficiency result against this 1 A module. It is useful for comparing design work, external magnetics and routing flexibility. Select equivalent load requirements before comparing actual BOM cost or board performance.
The practical selection is therefore conditional. Choose LMZM23601SILR when its current, voltage and temperature envelope fits and compact implementation has value. Choose a discrete architecture when control over magnetics, current scaling or placement justifies the additional design effort. For either choice, the final schematic, layout and test conditions determine the credible footprint, EMI and thermal conclusions.